Essentials of geology a comprehensive manual with 1300+ MCQs, answers, feedbacks, and illustrative figures by Ali Kareem Neamah - HTML preview

b) False physical or chemical characteristics.

Feedback: If you equate all Earth history to one calendar year, all recorded human history

occupies only the last 34 seconds of December

31 in our analogy.

 

a) -------------------------------------------------------------- -------------------------------------------------------------- 1189. Correlation matches up rock layers 1191. James Hutton pioneered radiometric across distances on the basis of similar age dating. sequences of rock layers and similar fossils a) True in the layers. b) False True b) False Feedback: James Hutton did not pioneer radiometric age dating. Here is why: Feedback: Correlation in geology involves James Hutton was a Scottish geologist who matching rock layers across different locations lived from 1726 to 1797. He is considered the based on similarities in their sequences and the father of modern geology and the originator of fossils found within them. This helps geologists the principle of uniformitarianism, which states establish the relative ages of rock formations that the present is the key to the past and that and build a coherent picture of Earth's natural processes operate at the same rates geological history. and in the same ways throughout geologic time. Radiometric age dating is a technique that uses

the decay of radioactive isotopes to measure

the age of materials such as rocks or fossils. It

was first developed in the early 20th century,

long after Hutton’s death, by scientists such as

Ernest Rutherford, Bertram Boltwood, Arthur

Holmes, and Willard Libby. Hutton did not have

access to radiometric age dating methods, but

he used other lines of evidence, such as the

 

a) 1190. The boundary surface between two was much older than commonly believed at his stratigraphic formations is called a key bed. time. He estimated that the Earth was millions True or even billions of years old, while most of his -------------------------------------------------------------- fossil succession in rocks, to infer that the Earth unconformities, cross-cutting relationships, and

b) False contemporaries adhered to a biblical

Feedback: The boundary surface between two around 4000 BC. chronology that placed the Earth’s creation at stratigraphic formations is not called a key bed, --------------------------------------------------------------

 

separate. Contacts can be conformable, period of potassium-40 is half of this, and the meaning that the layers are continuous and number of years is cut in half for each parallel, or unconformable, meaning that there succeeding half-life period. two different rock types or ages meet and 40 is 1.3 billion years; the second half-life but a contact. A contact is the surface where 1192. The first half-life period of potassium-

is a gap or discordance between the layers due a) True to erosion or deformation. A key bed, also b) False called a marker bed, is a distinctive layer of rock

serves as a useful marker or reference horizon potassium-40 is 1.3 billion years, but the or sediment within a sequence of layers that Feedback: The first half-life period of

for correlation and dating purposes. Key beds second half-life period of potassium-40 is also are valuable in stratigraphy, which is the study 1.3 billion years, and the number of years

 

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remains the same for each succeeding half-life Feedback: Eighteenth- and nineteenth-century period. Here is why: scientists did attempt to estimate the age of the

The half-life of a radioactive substance is Earth using various methods, including the

defined as the time for half of the original nuclei analysis of sediment thickness, rates of

to decay (or the time at which half of the original geologic processes, and Earth's temperature.

nuclei remain). The half-life of a radioactive However, these early attempts had crucial flaws

substance is constant and does not depend on and often resulted in incorrect and inconsistent

how much material is left or how long it has age estimates. It wasn't until the development

been decaying. of radiometric dating methods in the 20th

Therefore, the first half-life period of potassium- century that more accurate estimates of Earth's

40 is 1.3 billion years, which means that after age were obtained. this time, half of the original amount of --------------------------------------------------------------

potassium-40 will decay into argon-40. The 1195. Grains of zircon in Australian second half-life period of potassium-40 is also sandstones have been dated at 4.57 billion

1.3 billion years, which means that after another years old, which is the currently accepted

1.3 billion years, half of the remaining amount age of Earth. of potassium-40 will decay into argon-40. The a) True number of years does not change for each b) False succeeding half-life period, but the amount of

potassium-40 decreases by half each time. Feedback: Grains of zircon in Australian For example, if we start with 100 g of sandstones have been dated at 4.57 billion

potassium-40, then after one half-life (1.3 billion years old, but this is not the currently accepted

years), we will have 50 g of potassium-40 and age of Earth. The currently accepted age of

50 g of argon-40. After two half-lives (2.6 billion Earth is estimated to be 4.54 ± 0.05 billion years

years), we will have 25 g of potassium-40 and (4.54 × 10^9 years ± 1%). This age may

75 g of argon-40. After three half-lives (3.9 represent the age of Earth’s accretion, or core

billion years), we will have 12.5 g of potassium- formation, or of the material from which Earth

40 and 87.5 g of argon-40, and so on. formed. This dating is based on evidence from

-------------------------------------------------------------- radiometric age-dating of meteorite material

1193. Closure temperature is: and is consistent with the radiometric ages of

a) The temperature at which a rock system the oldest-known terrestrial material and lunar

ceases to interchange parent or daughter samples. The grains of zircon in Australian

product with surrounding material. sandstones are from the Jack Hills of Western

b) The temperature cutoff below which Australia, and they are the oldest-known

radiometric decay occurs at a fixed half-life minerals on Earth. They have been dated by

for each particular isotope. using uranium-lead isotopic analysis to be

c) The temperature below which each of the between 4.4 and 4.57 billion years old, which

geologic features that is a Principle of means they formed very soon after the Earth

Relative Age-Dating is stable and reliable. itself. However, these zircons are not

d) The temperature below which the Principle representative of the bulk composition of the

of Baked Contacts is valid. Earth, as they are derived from ancient granites

e) The temperature at which the parent isotope that have been eroded and transported by

N-40 ceases to decay to Ar-39. water. Therefore, they do not give a direct date

for the age of the Earth, but rather a lower limit

Feedback: Closure temperature is the for it. temperature at which a mineral or rock has

cooled to the point where it no longer allows the

exchange of parent or daughter isotopes with

its surroundings. This is a critical concept in

radiometric dating because it represents the

point at which the "clock" for radioactive decay

starts. Above the closure temperature, isotopic

exchange can occur, and below it, the isotopic

ratios remain fixed and can be used for dating

purposes.

--------------------------------------------------------------

1194. Eighteenth- and nineteenth-century --------------------------------------------------------------

scientists tried to determine Earth’s age by 1196. The largest subdivisions of time on the analyzing the thickness of sediments, the geologic column are eras, which are broken

rates of geologic processes, and Earth’s down into smaller units called eons, then temperature, but crucial flaws in these periods, then epochs. techniques gave incorrect ages. a) True

a) True b) False b) False

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Feedback: The largest subdivisions of time on Collecting a rock sample: This involves the geologic column are eons, which are broken finding a suitable rock that contains the

down into smaller units called eras. Eras are minerals or fossils that are suitable for

further divided into periods, and periods are radiometric dating. For example, some

subdivided into epochs. So, the correct order is: minerals such as zircon, biotite, and muscovite

Eon > Era > Period > Epoch. are commonly used for uranium-lead dating,

-------------------------------------------------------------- while some fossils such as wood or bone are

1197. The oldest rocks found so far in our commonly used for carbon-14 dating. The rock

solar system are 4.57 billion year old sample should be large enough to provide

meteorites, leading scientists to conclude enough material for analysis, and should be

that this is the approximate age of Earth. free of contamination or alteration by

a) True weathering or metamorphism. b) False Separating the minerals of interest: This

involves crushing the rock sample and

Feedback: The statement is true. Scientists separating the minerals or fossils that contain

use the age of meteorites to estimate the age the isotopes of interest from the rest of the rock.

of the Earth because meteorites are thought to This can be done by using physical methods

have formed from the same cloud of gas and such as sieving, magnetic separation, or

dust that formed the Earth and the rest of the density separation, or by using chemical

solar system. Therefore, the oldest meteorites methods such as dissolution, precipitation, or

are thought to be approximately the same age extraction. The separated minerals or fossils

as the Earth. Other evidence that supports the are then cleaned and prepared for further

age of the Earth being 4.57 billion years old analysis. includes: Extracting the isotopes of interest: This The age of the oldest rocks found on Earth, involves isolating the parent and daughter

which are about 4.4 billion years old. isotopes from the minerals or fossils by using

The age of the Moon, which is thought to have various techniques such as mass spectrometry,

formed from a collision between the Earth and alpha spectrometry, beta counting, or liquid

another object about 4.5 billion years ago. scintillation counting. These techniques

The age of the oldest stars, which are about measure the mass, energy, or radiation emitted

13.8 billion years old. The Earth is thought to by the isotopes and separate them according to

have formed much later than the first stars. their atomic number or mass number. -------------------------------------------------------------- Measuring the concentrations and ratio of

1198. What are the four steps of radiometric the two isotopes: This involves calculating the

age dating a geologic material? amounts and ratios of the parent and daughter

a) Collecting a rock sample; separating the isotopes in the sample by using mathematical

minerals of interest; extracting the isotopes formulas or calibration curves. These values

of interest; measuring the concentrations are then used to determine the age of the

and ratio of the two isotopes. sample by using the radioactive decay law and

b) Collecting a rock sample; grinding the the half-life of the parent isotope. The age can

entire rock sample; extracting the isotopes be expressed as an absolute age in years, or

of interest; measuring the concentrations as a relative age in terms of geological periods

and ratio of the two isotopes. or events.

c) Collecting a rock sample; grinding the --------------------------------------------------------------

entire rock sample; mixing in a control 1199. Which of the following methods may be amount of the parent isotope; measuring used to age-date a sedimentary rock? the concentrations and ratio of the two a) Magnetostratigraphy. isotopes. b) Dendrochronology.

d) Collecting a rock sample; grinding the c) Seasonal changes in growth rings in

entire rock sample; measuring the travertine deposits and shelled organisms.

concentrations & ratio of the two isotopes; d) Radiometric decay. testing the half-life at the average e) None of the possible answers are correct. temperature and pressure at which the rock

has existed. Feedback: Sedimentary rocks are rocks that

e) All the possible steps are necessary. are formed by the accumulation and

cementation of sediments, such as sand, clay,

Feedback: Radiometric dating is a technique or organic matter. Sedimentary rocks can be

that uses the decay of radioactive isotopes to difficult to date directly using radiometric

measure the age of materials such as rocks or methods, which are based on the decay of

fossils. It relies on measuring the proportions of radioactive isotopes within minerals. This is

a parent isotope and its daughter product in a because sedimentary rocks are composed of

sample, and knowing the half-life of the parent. fragments of other rocks that have been

The four steps of radiometric age dating a eroded, transported, and deposited over time,

geologic material are: and may have lost or gained some isotopes

247

during these processes. Therefore, none of the Feedback: Lord Kelvin initially estimated the possible answers are correct, as they are not age of the Earth based on its cooling rate,

methods that can be used to age-date a assuming it was a solid body. However, the

sedimentary rock directly. However, some of discovery of radioactive decay in the early 20th

these methods can be used to date other century provided a more accurate method for

materials or events that are associated with dating the Earth's age. Radioactive decay

sedimentary rocks, such as fossils, volcanic releases heat, affecting the Earth's

ash layers, or glacial deposits. temperature, and this process was not

-------------------------------------------------------------- considered in Kelvin's calculations. The

1200. Which of the following statements is recognition of radioactive decay as a significant

FALSE? factor led to the realization that Kelvin's

a) Conglomerates containing land plants estimate was too young. This highlights the

probably formed in an alluvial fan or a importance of considering multiple factors in

stream channel. determining the Earth's age.

b) Marine limestone overlying alluvial-fan --------------------------------------------------------------

conglomerate indicates the sea level rose 1202. Which of the following is NOT useful in at that site. identifying mountain belts that have eroded

c) Limestone containing coral fossils probably away and therefore do not have obvious

developed in a shallow sea. topographic features?

d) Gneiss radiometrically dated as 4.4 billion a) Folds and faults.

years old is the oldest whole rock yet found. b) Unconformities.

e) Igneous and metamorphic rocks are c) Coesite, a variety of quartz.

commonly found in mountain belts. d) Foreland sedimentary basins.

e) Basement uplifts.

Feedback: The oldest whole rock yet found is not gneiss, but a type of rock called faux Feedback: Coesite is not useful in identifying amphibolite, which is an ancient volcanic mountain belts that have eroded away because

deposit. The faux amphibolite rocks are part of it is a high-pressure polymorph of quartz that

the Nuvvuagittuq greenstone belt in northern forms under very high pressure and moderate

Quebec, Canada, and they have been dated to temperature conditions, such as those

be between 3.8 and 4.28 billion years old. produced by meteorite impacts or deep

Gneiss is a type of metamorphic rock that forms subduction. Coesite is not related to mountain

from the high-temperature and high-pressure building or erosion, and is usually found in very

alteration of other rocks, such as granite or small grains within other rocks. schist. Gneiss has a banded or foliated texture,

and is composed of minerals such as quartz,

feldspar, mica, and hornblende. The oldest

gneiss rocks found on Earth are from the

Acasta Gneiss in Canada’s Northwest Territories, and they are about 4.03 billion years

old. However, these gneiss rocks are not the

oldest whole rocks, but rather fragments of

older rocks that have been reworked by

metamorphism.

--------------------------------------------------------------

1201. How was Lord William Kelvin’s --------------------------------------------------------------

estimate of the age of Earth affected by the 1203. Identify the FALSE statement. There is

discovery of radioactive decay? very little rock record for Earth’s first 400

a) There was no affect upon his estimated age million years because:

of Earth. a) The surface was one vast ocean of hot

b) water. Scientists realized his estimated age was

too old. b) Intense meteorite bombardment may have

c) Scientists realized his estimated age was destroyed land surfaces & exposed rock.

too young because he had missed a c) Nearly all rock older than 3.6 Ga has been decimal place when using halflife in his destroyed by erosion or metamorphised.

calculation. d) Surface rock was so hot that the

d) Age-dating via radioactive decay eventually radiometric clock were not working to

showed that his estimated age of Earth was record time. almost accurate.

e) Feedback: This statement is not accurate. Scientists realized his estimated age was

too young because he had overestimated While the early Earth did experience extreme

how quickly Earth was cooling off. conditions, it wasn't a "vast ocean of hot water."

Instead, it had a dynamic environment with

volcanic activity, and the presence of water in

248

both liquid and vapor forms. The conditions pressures, high salinity, high acidity, and low

were harsh, with frequent volcanic eruptions, oxygen levels. They also had to find sources of

but it wasn't a uniform ocean of hot water. energy and carbon to sustain their metabolism

-------------------------------------------------------------- and growth. Oxygenated ocean water and

1204. Which geologic time interval saw the atmosphere didn’t exist when the earliest life

first continents, the first life, and possibly the forms began, and the ability of organisms to

first plates? extract energy from sunlight didn’t evolve until

a) Hadean later. b) Phanerozoic --------------------------------------------------------------

c) Proterozoic 1207. Which of the following is NOT one of d) Paleozoic the smaller continents formed by the break

e) Archean up of Pannotia?

a) Laurentia

Feedback: The Archean Eon is the second b) Siberia oldest of the four eons of Earth’s geologic time c) Laramidia scale, lasting from about 4.0 to 2.5 billion years d) Baltica ago. It is preceded by the Hadean Eon, which e) Gondwana is an informal interval that extends from about

4.6 to 4.0 billion years ago, and followed by the Feedback: Pannotia was a supercontinent that Proterozoic Eon, which lasts from about 2.5 to existed during the late Neoproterozoic era,

0.541 billion years ago. The Archean Eon saw about 600 million years ago. It formed when the

the first continents, the first life, and possibly the previous supercontinent Rodinia broke up and

first plates on Earth. reassembled, and it broke up again into smaller

-------------------------------------------------------------- continents that later formed the basis of the

1205. Which of the following has nothing to modern continents. The smaller continents that

do with fossils? formed by the break up of Pannotia were:

a) Stromatolites Laurentia, which included most of present-day b) Rodinia North America, Greenland, Scotland, and parts

c) Cyanobacteria of Ireland and Norway. d) Ediacaran fauna Siberia, which included most of present-day e) Conodonts Siberia and parts of Kazakhstan and Mongolia.

Baltica, which included most of present-day

Feedback: Rodinia is not a fossil, but a name northern Europe, such as Scandinavia, Finland,

given to a supercontinent that existed between Poland, Germany, and the Baltic states. about 1.2 and 0.75 billion years ago. It was Gondwana, which included most of present-composed of several landmasses that later day South America, Africa, India, Australia,

broke up and reassembled to form other Antarctica, Arabia, and parts of southern

supercontinents, such as Pannotia and Europe and Asia. Pangaea. --------------------------------------------------------------

-------------------------------------------------------------- 1208. Which of the following has nothing to 1206. Which of the following statements is do with the K-T (Cretaceous-Tertiary)

FALSE? The first life forms: boundary?

a) Occurred in oxygen-rich, shallow, warm a) Iridium.

ocean waters. b) Shocked quartz.

b) Were simple cells of bacteria and c) Chicxulub.

cyanobacteria (blue-green algae). d) Bolide (meteorite).

c) Lived in the Archean eon. e) Banded-iron formations. d) Date back to between 3.5 and 3.8 billion

years. Feedback: Banded-iron formations (BIFs) are

e) Were prokaryotic cells. associated with the oxygenation of Earth's

atmosphere, but this event occurred long

Feedback: The first life forms on Earth did not before the K-T (Cretaceous-Tertiary) boundary.

occur in oxygen-rich, shallow, warm ocean BIFs are sedimentary rocks that primarily

waters, but rather in oxygen-poor, deep, hot formed between 2.5 and 1.8 billion years ago

hydrothermal vents or in oxygen-poor, shallow, during the Archean and Proterozoic Eons.

acidic coastal waters. The first life forms on These formations are characterized by

Earth were simple cells of bacteria and alternating bands of iron-rich and silica-rich

cyanobacteria (blue-green algae) that lived in minerals, and they are significant in the

the Archean eon, between 3.5 and 3.8 billion geological record as indicators of past changes

years ago. These life forms were prokaryotic in Earth's atmospheric and oceanic conditions.

cells, which means they lacked a nucleus and Iridium: Iridium is indeed associated with other membrane-bound organelles. The first life extraterrestrial objects like meteorites. Elevated

forms on Earth had to cope with harsh iridium levels at the K-T (Cretaceous-Tertiary)

conditions, such as high temperatures, high boundary played a crucial role in supporting the

249

hypothesis that an asteroid impact was 1211. Identify the FALSE statement. Internal responsible for the mass extinction event. differentiation: Shocked quartz: This type of quartz is created a) Resulted in Earth’s having different by the immense pressure generated during materials at different depths within itself. impact events, making it an important indicator b) Began when Earth partially melted 4.5 Ga. of asteroid or meteorite impacts. It is indeed c) Involved heavy molten iron sinking to relevant to the study of the K-T boundary. Earth’s center. Chicxulub: The Chicxulub crater, located on d) "Stirred" Earth’s interior and hastened the Yucatán Peninsula in Mexico, is the impact Earth’s cooling. site associated with the asteroid or meteorite e) Happened before, or possibly impact that is believed to have caused the mass simultaneously with, Earth’s collision with a

extinction event at the K-T boundary. protoplanet. Bolide (meteorite): Bolides are indeed extraterrestrial bodies like meteorites. In the Feedback: Earth's internal differentiation, context of the K-T boundary, the impact of a which led to the formation of distinct layers

large bolide is thought to have led to the mass based on density, did not hasten Earth's

extinction. cooling. In fact, it had the opposite effect and

-------------------------------------------------------------- significantly slowed down Earth's cooling

1209. This common, cheap, and useful form process. This is because the separation of

of limestone consists of microscopic marine materials into different layers created insulation

algae shells and shrimp feces. Thick and reduced the rate at which heat could

Cretaceous-age deposits of it are common escape from the planet's interior. in Europe.

a) Sand

b) Iron

c) Siliceous silt

d) Chalk

e) Clay

Feedback: Chalk is a type of limestone primarily composed of microscopic marine

algae shells and other organic debris. It is a

common rock found in Cretaceous-age

deposits in various parts of the world, including

Europe.

--------------------------------------------------------------

1212. Which of the following statements is

FALSE?

a) Human ancestors first appeared in the late

Mesozoic.

b) The human genus Homo first appeared

more than 2 million years ago.

c) Fossils of modern humans (Homo sapiens)

date back to about 150,000 years ago.

-------------------------------------------------------------- d) The Cenozoic is known as the Age of

1210. Mammals. Which of the following are fossil plants? a) e) Huge mammals such as giant beavers, Trilobites.

b) bears, sloths, and mammoths lived during Gymnosperms and angiosperms.

c) the Cenozoic but are now extinct. Graptolites and archeocyathids.

d) Pterosaurs and plesiosaurs.

e) Feedback: Human ancestors, specifically the Bolides.

first primates, appeared in the Paleocene,

Feedback: which is part of the early Cenozoic era, not the Gymnosperms and angiosperms

are both types of fossil plants. Gymnosperms late Mesozoic. The Cenozoic era is often

include conifers, cycads, and ginkgoes, while referred to as the Age of Mammals and is when

angiosperms are flowering plants. These plant the evolution of early primates and, eventually,

fossils provide important insights into the the human genus Homo took place. history of plant evolution and Earth's past --------------------------------------------------------------

environments. 1213. The Great Oxygenation Event, which

Trilobites are Paleozoic animals; pterosaurs added abundant oxygen to the atmosphere

and plesiosaurs are Mesozoic reptiles; bolides beginning about 2.4 Ga, was due to the: are extraterrestrial bodies like meteorites. a) Greater abundance and variety of Edicaran

-------------------------------------------------------------- fauna.

 

250

b) Evolution of photosynthetic organisms. of oxygen-producing photosynthetic organisms

c) Evolution of multicellular organisms. during the Proterozoic and the Great

d) Appearance of photosynthetic plants on Oxygenation Event around 2.4 billion years

land. ago. Prior to that event, oxygen levels in Earth's

e) None of the possible answers is correct. atmosphere were minimal or virtually

nonexistent.

Feedback: Photosynthetic cyanobacteria, also --------------------------------------------------------------

known as blue-green algae, were some of the 1215. Identify the FALSE statement. earliest life forms capable of photosynthesis. a) During the Cenozoic, North and South They played a crucial role in releasing oxygen America became joined by the isthmus of

as a byproduct of photosynthesis, gradually Panama, creating the eventual need for a

leading to the oxygenation of Earth's canal. atmosphere during the Great Oxygenation b) Organisms with oxygen-based metabolism Event. The Great Oxygenation Event (GOE), produce energy efficiently, so they can

also known as the Oxygen Catastrophe or evolve larger bodies than nonoxygenated

Oxygen Revolution, occurred approximately organisms can. 2.4 billion years ago during the Proterozoic c) When climate warms, sea level goes down Eon. This event marked a significant turning due to increased evaporation. point in Earth's history and had a profound d) Shells on eggs keep them from drying out impact on the planet's atmosphere, biology, so the eggs and the mother aren’t tied to a and geology. Prior to the GOE, Earth's water environment. atmosphere had little to no oxygen (O2). The e) Humans shouldn’t call dinosaurs failures; early atmosphere was likely composed of they existed for more than 150 million

gases such as methane (CH4), carbon dioxide years, while our genus, Homo, has been

(CO 2), water vapor (H2O), and nitrogen (N2). around only 2.4 million years. However, the emergence and proliferation of

photosynthetic cyanobacteria fundamentally Feedback: When climate warms, sea level changed the composition of the atmosphere. actually goes up, not down, due to two main

Photosynthetic cyanobacteria were among the factors: thermal expansion and ice melt.

first organisms capable of harnessing sunlight Thermal expansion is the increase in volume of

to convert carbon dioxide and water into seawater as it heats up. Ice melt is the addition

organic matter while releasing oxygen as a of freshwater to the oceans from melting

byproduct. This process, known as oxygenic glaciers, ice sheets, and ice caps on land. As

photosynthesis, gradually increased the the global temperature rises, more ice on land

concentration of oxygen in the atmosphere over melts and flows into the sea, raising the water

millions of years. level. Evaporation is the process of liquid water

turning into water vapor and leaving the surface

of the ocean. Evaporation does not affect sea

level significantly because most of the water

vapor eventually returns to the ocean as

precipitation (rain or snow). The net change in

water volume due to evaporation and

precipitation is relatively small compared to

thermal expansion and ice melt.

--------------------------------------------------------------

1216. Identify the FALSE statement. a) Outgassing of mantle rock probably

 

a) component of Earth’s Hadean atmosphere? c) There was intense meteorite bombardment Hydrogen of Earth about 4 Ga that destroyed Earth’s b) Oxygen earliest crustal rock. c) Methane d) Eighty percent of Earth’s continental crust d) Ammonia existed by the end of the Hadean eon. e) Nitrogen e) 1214. b) The Moon is now almost 20 times as far Which of the following was NOT a from Earth as it originally was. -------------------------------------------------------------- created Earth’s early Hadean atmosphere.

Geologists generally agree that plate

Feedback: tectonics activity began in the Archean During the Hadean Eon, Earth's Eon.

early atmosphere was primarily composed of

 

gases such as hydrogen, methane, ammonia, Feedback: This statement is not accurate. and water vapor. It lacked significant amounts During the Hadean eon, Earth's surface was of oxygen. The presence of free oxygen in the dominated by intense volcanic activity, and the atmosphere is a relatively recent development formation of continental crust as we know it in Earth's history and is associated with the rise today had not yet occurred. Most of Earth's

251

continental crust formed during the Archean of supercontinents that existed at different

eon, not the Hadean eon. times in Earth’s history.

--------------------------------------------------------------

1219. Identify the FALSE statement. a) Dinosaurs are thought to have possibly

been warm-blooded reptiles.

b) A 1950s experiment with methane,

ammonia, and electric sparks suggested

that life could have originated in warm

surface waters, but scientists now believe

the atmosphere lacked sufficient methane

 

1217. Identify the FALSE statement. During from harmful ultraviolet rays. the Pleistocene Ice Age: d) Multiple orogenies over time create great a) Continental glaciers in the Northern mountain ranges; the Taconic, Acadian, Hemisphere advanced and retreated at and Alleghenian orogenies all produced the -------------------------------------------------------------- c) Atmospheric oxygen and nitrogen react to form nitrogen oxide, which protects land life and ammonia for this to have occurred.

b) Appalachians. least twenty times.

Sea level fell because water was tied up as

 

c) an interglacial time interval that began The continental shelf west of Alaska was 11,000 years ago. ice. e) We currently live in the Holocene, which is

exposed, and allowed migration of animals

d) Feedback: Atmospheric oxygen and nitrogen and people from Asia to North America.

joining Asia and North America and a do not react to form nitrogen oxide (NO The Bering Strait served as a land bridge

partial land bridge connected Asia to way that directly protects land life from harmful ultraviolet rays. Nitrogen oxides are produced x ) in a

e) through various chemical processes, including Australia.

America. combustion and lightning, but they primarily Continental glaciers covered all of North

contribute to air pollution and do not serve as a

 

Feedback: direct protective mechanism against UV During the Pleistocene Ice Age, radiation. The Earth's atmosphere provides continental glaciers did not cover all of North protection from UV rays through the presence America. While there were significant ice of the ozone layer. Oxygen (O sheets covering parts of North America, 2 ) can be converted to ozone (O particularly in the northern regions, they did not 3 ) in the upper atmosphere, which absorbs and scatters UV extend to cover the entire continent. radiation.

 

1218. Rodinia, Pannotia, Grenvillia, and a) Generated 2-km-high tsunamis. Pangaea are all names of supercontinents. b) Generated a hot-air blast and blaze that a) True caused worldwide forest fires. b) False c) Ejected debris into the atmosphere that caused months of winter-like night -------------------------------------------------------------- 1220. Geologists believe that the impact of a 13km wide meteorite 65 million years ago: --------------------------------------------------------------

 

Feedback: The Grenville is an orogeny not conditions that halted photosynthesis. supercontinent. It is a geological event that d) Ejected chemicals into the atmosphere that occurred during the Precambrian eon, produced acid rain. specifically during the Proterozoic era. It played e) All the possible answers are correct. a significant role in the formation of mountain ranges and the assembly of the supercontinent Feedback: Geologists believe that the impact Rodinia. The other three names are all names of a 13km wide meteorite 65 million years ago,

252

often associated with the Chicxulub crater in the 1222. Gymnosperms (naked-seed plants like Yucatán Peninsula, resulted in various conifers) were widespread in the late

catastrophic effects, including generated 2km Paleozoic and angiosperms (flowering

high tsunamis, generated a hot-air blast and plants) gained dominance in the late

blaze that caused worldwide forest fires, Mesozoic. ejected debris into the atmosphere that caused a) True months of winter-like night conditions that b) False halted photosynthesis, and ejected chemicals

into the atmosphere that produced acid rain. Feedback: Gymnosperms are seed plants that These combined effects contributed to the do not produce flowers or fruits, such as

mass extinction event known as the conifers, cycads, ginkgoes, and gnetophytes.

Cretaceous-Paleogene (K-T) extinction, which Angiosperms are seed plants that produce

had a profound impact on life on Earth, flowers and fruits, such as magnolias, roses,

including the extinction of the dinosaurs. apples, and grasses. Gymnosperms were

widespread in the late Paleozoic Era, which

lasted from about 541 to 252 million years ago.

Angiosperms gained dominance in the late

Mesozoic Era, which lasted from about 252 to

66 million years ago. Angiosperms diversified

rapidly and adapted to various habitats,

displacing many gymnosperms and becoming

the most diverse and abundant group of plants

on Earth.

--------------------------------------------------------------

 

-------------------------------------------------------------- the middle Paleozoic. True 1223. The first feathered birds appeared in 1221. a) Banded-iron formations ( BIFs ) are

forming today along mid-ocean ridges. b) False

a) True

b) Feedback: The first feathered bird, False

Archaeopteryx, appeared much later in the

Feedback: Jurassic Period of the Mesozoic Era, not in the Banded-iron formations ( BIFs ) are

not forming today along mid-ocean ridges. They middle Paleozoic. Archaeopteryx, one of the

are primarily associated with ancient geological earliest known feathered birds, existed during

periods, especially during the Archean and the Late Jurassic Period of the Mesozoic Era,

Proterozoic eons. These formations were around 150 million years ago. It is considered

created under specific conditions that were one of the transitional forms between feathered

prevalent in the past but are not commonly dinosaurs and modern birds. found in the modern oceans. Banded-iron

formations ( BIFs) are distinctive units of sedimentary rock consisting of alternating

layers of iron oxides and iron-poor chert. They

can be up to several hundred meters in

thickness and extend laterally for several

hundred kilometers. They are thought to record

the oxygenation of the Earth’s oceans by

photosynthetic cyanobacteria. The oxygen

combined with dissolved iron in seawater to

 

form insoluble iron oxides, which precipitated -------------------------------------------------------------- out, forming a thin layer on the ocean floor. 1224. Theoretically, " snowball Earth " of the Each band is similar to a varve, resulting from late Proterozoic Eon would have stayed ice- cyclic variations in oxygen production. covered forever were it not for greenhouse warming caused by carbon monoxide from volcanoes. a) True b) False

Feedback: The greenhouse warming that could have ended the snowball Earth was

caused by carbon dioxide (CO2), not carbon monoxide (CO), from volcanoes. Carbon

monoxide is a minor volcanic gas that does not

-------------------------------------------------------------- have a significant greenhouse effect, while

 

253

carbon dioxide is a major volcanic gas that can and move on land, but still depended on water

trap heat in the atmosphere. According to the for reproduction. Amphibians diversified and

snowball Earth hypothesis, the planet’s surface became abundant in the Carboniferous and

became entirely or nearly entirely frozen during Permian periods, but declined in diversity and

one or more of Earth’s icehouse climates, the abundance during the Mesozoic era due to

most recent of which occurred before 650 competition from reptiles and other vertebrates.

million years ago during the Cryogenian period. --------------------------------------------------------------

One of the challenges of this hypothesis is to 1226. The Paleozoic Era, like the Mesozoic explain how the Earth could escape from a Era, may have ended with mass extinction

frozen state. One possible solution involves the of life forms due to a huge meteorite impact.

outgassing of massive amounts of carbon a) True dioxide by volcanoes, which could have b) False warmed the planetary surface rapidly by

enhancing the planet’s so-called greenhouse Feedback: The Paleozoic Era ended with the effect, especially given that major carbon Permian–Triassic extinction event, which is dioxide sinks (rock weathering and thought to have been caused by intense

photosynthesis) would have been dampened volcanic activity. There is no evidence of a

by a frozen Earth. major meteorite impact during the Permian–

-------------------------------------------------------------- Triassic extinction event. The Mesozoic Era

1225. It wasn’t until the late Mesozoic that ended with the Cretaceous–Paleogene

vascular plants with woody tissues, seeds, extinction event, which is thought to have been

and veins shared the land with spiders, caused by the Chicxulub impact, a giant

scorpions, insects, and crustaceans, while asteroid or comet that struck Earth about 66

jawed fish cruised the oceans and the first million years ago. amphibians left water to visit land.

a) True

b) False

Feedback: Vascular plants with woody tissues, seeds, and veins existed long before the late

Mesozoic. The first vascular plants appeared in

the Silurian period, about 420 million years ago.

The first seed plants evolved in the Devonian

period, about 360 million years ago. The first

woody plants were also present in the Devonian

period, such as the progymnosperm

Archaeopteris. The first veins, or vascular --------------------------------------------------------------

bundles, are found in the stems and leaves of 1227. The continents that comprised

vascular plants. Pangaea came together in the early

Spiders, scorpions, insects, and crustaceans Paleozoic but began to split apart soon

are all arthropods, a diverse group of animals afterward, during the late Paleozoic. with jointed appendages and exoskeletons. a) True The first arthropods appeared in the Cambrian b) False period, about 540 million years ago. The first

spiders and scorpions evolved in the Silurian Feedback: The continents that comprised

period, about 430 million years ago. The first Pangaea came together during the late

insects appeared in the Devonian period, about Paleozoic, particularly during the Carboniferous

400 million years ago. The first crustaceans and Permian periods. Pangaea began to break

also emerged in the Cambrian period, and apart during the Mesozoic Era, not the late

diversified into many forms in the Ordovician Paleozoic. and Silurian periods.

Jawed fish are vertebrates that have jaws and

paired fins. They belong to the group

Gnathostomata, which evolved from jawless

fish in the Silurian period, about 440 million

years ago. Jawed fish include cartilaginous fish

(such as sharks and rays) and bony fish (such

as ray-finned fish and lobe-finned fish). Jawed

fish dominated the oceans throughout the

Paleozoic and Mesozoic eras.

The first amphibians were tetrapods, or four-

limbed vertebrates, that evolved from lobe-

finned fish in the Devonian period, about 370

million years ago. They were able to breathe air --------------------------------------------------------------

254

1228. For improved scientific accuracy, the to around 40,000 years ago, while the last

movie Jurassic Park should be renamed known evidence of Denisovans dates to around

"Cretaceous Park" because its largest 50,000 years ago. Therefore, Homo sapiens

dinosaur "villain," the Tyrannosaurus rex, coexisted with these other humanoid species

lived in the Cretaceous period. for at least 150,000 years, and possibly longer.

a) True

b) False

Feedback: The Tyrannosaurus rex lived in the Late Cretaceous period, which was about 68 to

66 million years ago. The Jurassic period was

earlier in the Mesozoic Era, and it ended about

145 million years ago. Therefore, the

Tyrannosaurus rex could not have lived in the

Jurassic period. In addition to the

Tyrannosaurus rex, there are a number of other

dinosaurs in the movie Jurassic Park that lived

in the Cretaceous period, such as the

The only dinosaurs in the movie that lived in the Triceratops, Velociraptor, and Brachiosaurus. --------------------------------------------------------------

 

a) compression; radioactive elements didn’t The Earth has experienced ice ages throughout its history. The first known ice yet exist to contribute heat energy. age occurred during the Proterozoic Eon, about True 2.4 billion years ago. There have been several b) False other ice ages since then, including the Cryogenian ice age (about 720 to 635 million Feedback: Radioactive elements were present years ago) and the Pleistocene ice age (about on Earth during the Hadean Eon. In fact, 2.58 million years ago to 11,700 years ago). radioactive elements played a major role in The Cenozoic Era is the current era, and it heating the Earth during the Hadean. began about 66 million years ago. So, the Earth -------------------------------------------------------------- True b) False 1229. During the Hadean, Earth kept getting hotter due to meteorite impact and Feedback: Compsognathus. ages until the Cenozoic Era. a) Jurassic period are the Dilophosaurus and the 1231. The Earth did not experience its first ice

 

Radioactive elements decay over time, did experience ice ages before the Cenozoic releasing heat energy in the process. This heat Era. energy helped to melt the Earth's interior and create the Earth's core. In addition to radioactive elements, meteorite impacts and

compression also contributed to the Earth's

heat during the Hadean. However, radioactive

elements were a major source of heat during

this time period.

 

1230. Homo sapiens (modern humans) -------------------------------------------------------------- coexisted with other humanoid species --------------------------------------------------------------

 

a) 500,000 to 50,000 years ago. a) Slash-and-burn agricultural practices of b) 350,000 to 35,000 years ago. early humans. c) 2.5 million to approximately 11,000 years b) The closing of a sea-gap between North ago. America and South America. d) when to when? contributed to the onset of the modern ice ages? (Neanderthals and Dinisovans) from about 1232. Which of the following may have

 

e) 25,000 to approximately 11,000 years ago. A Miocene-Pliocene c) –boundary meteorite 200,000 to 25,000 years. impact. d) Increased thermohaline circulation in the Feedback: This is because Homo sapiens, or world’s oceans . modern humans, evolved in Africa around e) The uplift of the Sierra Nevada range, in 200,000 years ago and began to disperse out western North America. of Africa around 60,000 years ago. During their migration, they encountered and interbred with Feedback: The onset of the modern ice ages, other types of humans, such as Neanderthals or the Late Cenozoic Ice Age, was influenced and Denisovans, who had already occupied by several factors, such as changes in the Eurasia for hundreds of thousands of years. Earth’s orbit, atmospheric composition, plate The last known evidence of Neanderthals dates

255

tectonics, ocean currents, and volcanic activity. dissolved into these newly formed oceans. This

The closing of a sea-gap between North process played a crucial role in shaping Earth's

America and South America, also known as the atmosphere and creating the conditions for the

formation of the Isthmus of Panama, was one development of life as we know it today. The

of the major events that affected the global removal of significant amounts of water vapor

climate and contributed to the glaciation of and carbon dioxide contributed to the

Antarctica and the Northern Hemisphere. The dominance of nitrogen in our current

isthmus formed around 3 million years ago and atmosphere. The Great Oxygenation Event,

altered the ocean circulation patterns, leading which occurred much later, introduced oxygen

to a cooler and drier climate in many regions. as a significant component of the atmosphere

-------------------------------------------------------------- and had a profound impact on the evolution of

1233. The modern Alpine-Himalayan life on Earth.

mountain chain can be attributed to all of the

following except:

a) Northward drift of parts of former

Gondwanaland.

b) Continent-continent convergence.

c) Buoyancy of continental crust.

d) Plate tectonic processes.

e) The Grenville Orogeny.

Feedback: The modern Alpine-Himalayan mountain chain is a result of the collision of the

African, Arabian, and Indian plates with the

Eurasian plate over the past 100 million years.

This collision is driven by plate tectonic

processes, which involve the movement and

interaction of large segments of the Earth’s crust and upper mantle. The collision also

involves continent-continent convergence,

which means that two continental plates are

pushing against each other, creating high

mountains and deep crustal roots. The

buoyancy of continental crust, which is less

dense than oceanic crust and mantle material,

prevents it from being subducted into the

mantle, and instead causes it to deform and

uplift. The Grenville Orogeny was a much older --------------------------------------------------------------

event that occurred between 1.3 and 1 billion 1235. Approximately what percentages of years ago, during the Mesoproterozoic era. It plankton species and plant species,

was associated with the assembly of the respectively, died off at the time of the

supercontinent Rodinia, which later broke apart Cretaceous-Tertiary impact event? to form the precursors of the modern a) Approximately 95 percent of plankton continents. The Grenville Orogeny affected a species and 80 percent of plant species.

large portion of North America, as well as parts b) Approximately 99 percent of plankton of Europe and Africa, but it had no direct species and 85 percent of plant species.

connection to the formation of the Alpine- c) Approximately 95 percent of plankton Himalayan mountain chain. species and 80 percent of plant species.

-------------------------------------------------------------- d) Approximately 80 percent of plankton 1234. Prior to the formation of oceans of species and 50 percent of plant species.

liquid water, Earth’s atmosphere consisted e) Approximately 50 percent of plankton primarily of: species and 40 percent of plant species.

a) H2O (water, but primarily in steam [water

vapor] form) and carbon dioxide. Feedback: This is because the Cretaceous-

b) Nitrogen and carbon dioxide. Tertiary impact event, also known as the

c) Nitrogen and methane. Cretaceous-Paleogene extinction event, was a

d) Nitrogen and oxygen. sudden mass extinction of three-quarters of the

e) Carbon dioxide, methane, and hydrogen plant and animal species on Earth,

sulfide. approximately 66 million years ago. The event

was caused by the impact of a massive asteroid

Feedback: The early Earth's atmosphere was that created a global environmental

composed primarily of water vapor and carbon catastrophe, mainly through blocking sunlight

dioxide. As the planet cooled, water vapor and halting photosynthesis. condensed to form oceans, and carbon dioxide

256

The impact event had a devastating effect on a) The Arkanasian Orogeny. marine life, especially plankton, which are the b) The Appalachian Orogeny. base of the ocean food chain. Plankton include c) The Grenville Orogency. microscopic algae (phytoplankton) and animals d) The Hercynian Orogeny. (zooplankton) that float in the water. The impact e) The Alleghanian Orogeny. event reduced the amount of light and nutrients

available for plankton, causing a massive die- Feedback: The evidence of the Alleghanian off of about 95 percent of plankton species. Orogeny can be found in both the Ouachita and

The impact event also affected terrestrial life, Appalachian Mountains. This orogeny was a

especially plants, which rely on photosynthesis significant tectonic event during the late

to produce energy and oxygen. The impact Paleozoic era, and it resulted in the formation

event created dust, smoke, and ash that of these mountain ranges. blocked sunlight and reduced global

temperatures. This caused a widespread loss

of vegetation and a decline in plant diversity.

About 80 percent of plant species went extinct,

especially those that were adapted to warm and

humid climates.

 

--------------------------------------------------------------

1238. What is an epicontinental sea? a) A long, narrow sea near a continent. b) A sea of intermediate salinity, less saline

 

1236. A shallow sea found along the edge of a Which of the following was NOT a continent. characteristic of the Cretaceous period? e) A sea into which clastic-dominated a) Eruption of huge basalt plateaus at several sediments are being deposited. -------------------------------------------------------------- c) A shallow sea present on continental crust. d) than normal ocean water.

 

c) ocean ridges. sea that covers part of a continent. It is also known as an epeiric sea. It is usually connected Expansion of Earth due to the increased to an ocean by a river, strait or “arm of the sea”. rate of crustal formation. An epicontinental sea is different from a bay, d) Unusually high sea levels. which is directly connected to the ocean. An b) Unusually rapid generation of new oceanic Feedback: An epicontinental sea is a shallow crust and high spreading rates at mid-places on the ocean floor.

e) Unusually warm average global climate. epicontinental sea may form when the sea level

 

Feedback: rises or the land sinks due to tectonic Characteristics of the Cretaceous movements. An example of an epicontinental period included the eruption of large basalt sea is the Baltic Sea, which lies in the middle of plateaus on the ocean floor, unusually rapid a shield and was the centre of an ice sheet generation of new oceanic crust with high during the Quaternary glaciations. spreading rates at mid-ocean ridges, and -------------------------------------------------------------- unusually high sea levels. These factors 1239. Which statement about what are now contributed to the warm, greenhouse climate of the West Coast and the East Coast of North the Cretaceous period. The expansion of Earth America is true , with respect to the early- due to increased crustal formation is not a middle Paleozoic Era? characteristic of the Cretaceous period. While a) Both the West Coast and the East Coast the other options describe conditions and were experiencing orogenyrilobites. features of the Cretaceous period, the idea of b) Both the West Coast and the East Coast Earth's expansion is not supported by scientific were passive margins. evidence related to this specific geologic time c) The West Coast was a passive margin, and period. the East Coast was experiencing orogeny. -------------------------------------------------------------- d) The West Coast was experiencing 1237. Evidence of which orogeny can be orogeny, and the East Coast was a passive found in both the Ouachita and Appalachian margin. Mountains?

 

257

e) The West Coast was experiencing uniformitarianism, which suggests that the

orogeny, and the East Coast was subsiding processes we observe today on Earth have

regionally. been operating in a similar manner throughout

geological history. Hutton's ideas laid the

Feedback: During the early-middle Paleozoic foundation for the development of modern

Era, the West Coast of North America was a geological principles and the understanding of

passive margin. A passive margin is a Earth's long history. His work, including his

geological term for a continental margin that is book "Theory of the Earth," significantly

not an active plate boundary. It typically contributed to the field of geology and our

experiences relatively little tectonic activity, understanding of Earth's processes and history.

such as mountain building or major

earthquakes. In contrast, the East Coast of

North America was experiencing orogeny

during this time. Orogeny refers to the process

of mountain building, typically associated with

the collision of tectonic plates. The collision of

continents and the resulting compression of

rocks can lead to the formation of mountain

ranges, and this was happening along the

eastern margin of North America during the

 

1240. 1242. In which type of radioactive decay is a Banded-iron formations contain layers fast-moving electron emitted from a neutron of what rock or mineral, in between the in the nucleus? layers of iron oxides? -------------------------------------------------------------- -------------------------------------------------------------- early-middle Paleozoic Era.

 

a) a) Alpha decay Calcite or limestone. b) Beta decay b) Dolomite or limestone. c) Electron capture c) Any carbonate minerals or marble. d) Fission track d) Halite or other evaporite rock or minerals. e) None of the previous answers. e) Quartz or chert.

 

Feedback: Feedback: In beta decay, a neutron in the Banded iron formation consists of nucleus is transformed into a proton, and a fast- layers of iron oxides (typically either magnetite moving electron (beta particle) is emitted. This or hematite) separated by layers of chert (silica- process helps to maintain the balance of rich sedimentary rock). Chert is a fine-grained protons and neutrons in the nucleus. The other sedimentary rock composed of microcrystalline options mentioned represent different types of or cryptocrystalline quartz. It may also contain radioactive decay, but only beta decay involves small amounts of other minerals such as the emission of a fast-moving electron. calcite, dolomite, or iron oxides. Chert is often

red in color due to the presence of hematite.

 

-------------------------------------------------------------- --------------------------------------------------------------

1241. Who is generally considered the 1243. Because of the heat and pressure

founder of modern geology? exerted during metamorphism, daughter

a) Werner atoms were driven out of a mineral being

b) Lyell analyzed for a radiometric date. The date

c) Steno obtained from this mineral will, therefore, be

d) Cuvier _________ its actual age of formation. e) Hutton a) Younger than.

b) Older than.

Feedback: James Hutton, an 18th-century c) The same as. Scottish geologist, is often regarded as the d) It can’t be determined. founder of modern geology. He is best known e) None of the previous answers. for his pioneering work on the concept of

 

258

Feedback: Radiometric dating assumes that 1246. What is being measured in radiometric the system is closed, meaning that no parent or dating is: daughter atoms are added or removed from the a) The time when a radioactive isotope sample. If this assumption is violated, then the formed. date obtained will be inaccurate. For example, b) The time of crystallization of a mineral if some of the daughter atoms are driven out of containing an isotope. the sample by heat and pressure during c) The amount of the parent isotope only. metamorphism, then the ratio of parent to d) When the dated mineral became part of a daughter atoms will be higher than it should be, sedimentary rock. and the date will appear older than the actual e) When the stable daughter isotope was age of formation. Conversely, if some of the formed. parent atoms are lost from the sample, then the

ratio of parent to daughter atoms will be lower Feedback: Radiometric dating measures the than it should be, and the date will appear relative proportions of a radioactive parent

younger than the actual age of formation. It's isotope and its stable daughter product in a

important to note that radiometric dating is a sample, and uses the known rate of decay of

powerful tool when applied appropriately and the parent to estimate the age of the sample.

under the right conditions, but the potential for The parent isotope must have been

sample contamination or alteration must always incorporated into the sample at the time of its

be considered when interpreting the results. formation, which is usually the time of

-------------------------------------------------------------- crystallization of a mineral. The other options

1244. If a flake of biotite within a sedimentary are incorrect because they do not reflect the

rock (such as a sandstone) is radiometrically actual process of radiometric dating. dated, the date obtained indicates when: --------------------------------------------------------------

a) The biotite crystal formed. 1247. The idea that the facies seen in a b) The sedimentary rock formed. vertical sequence replace one another

c) The parent radioactive isotope formed. laterally is: d) The daughter radioactive isotope(s) a) Smith’s dictum.

formed. b) Walter’s law.

e) None of the previous answers. c) Steno’s principle.

d) Gressly’s model.

Feedback: Biotite is a mineral that can be used e) Darwin’s theory.

 

dating technique that measures the ratio of 87Rb Feedback: Walther’s law, named after the 87 to for rubidium-strontium dating, a radiometric Sr in a sample. The decay of 87Rb to 87Sr geologist Johannes Walther (1860-1937),

occurs at a constant rate, and the initial ratio of states that the vertical succession of facies

these isotopes depends on the source of the reflects lateral changes in environment. This

magma from which the biotite crystallized. means that the different types of sedimentary

Therefore, by measuring the current ratio of rocks or sediments that are stacked vertically

87Rb to 87Sr in a biotite flake, one can estimate on top of each other were deposited in adjacent

the age of the biotite crystal, which reflects the environments that shifted horizontally over

time when it formed from the magma. time. For example, a vertical sequence of

-------------------------------------------------------------- sandstone, shale, and limestone may indicate a

1245. The atomic number of an element is transition from a beach, to a lagoon, to a reef

determined by the number of __________ in environment. Walther’s law is based on the its nucleus. observation that the present-day distribution of

a) Protons. sedimentary environments is spatially

b) Neutrons. continuous and can be traced laterally.

c) Electrons. Therefore, the same principle can be applied to

d) Protons and neutrons. the past, assuming that the sedimentation was

e) Protons and electrons. continuous and uninterrupted by erosion or

non-deposition.

Feedback: Protons are positively charged --------------------------------------------------------------

particles that are found in the center of the 1248. The most commonly used time-atom, along with neutrons, which have no stratigraphic unit is the: charge. The number of protons in the nucleus a) System defines the identity and chemical properties of b) Period the element. For example, hydrogen has one c) Epoch proton in its nucleus, so its atomic number is 1. d) Member Helium has two protons in its nucleus, so its e) Formation atomic number is 2. The elements are arranged

in the periodic table in order of increasing Feedback: A time-stratigraphic unit, or a atomic number. chronostratigraphic unit, is a body of rock that

-------------------------------------------------------------- is defined by the geological formations that

259

were formed during a specific interval of different adaptations and preferences for their

geologic time. Each of its boundaries is habitats. synchronous, meaning that they represent the

same moment in time across the globe.

A system is a time-stratigraphic unit that

corresponds to a period in geologic time. A

period is a subdivision of an era, which is a

major division of geologic time. For example,

the Jurassic period is part of the Mesozoic era,

and the Jurassic system is the body of rock that

was formed during the Jurassic period. A

system may consist of several series, which are

smaller time-stratigraphic units that correspond

to epochs in geologic time. An epoch is a

subdivision of a period, which is a smaller

division of geologic time. For example, the

Paleocene epoch is part of the Paleogene

period, and the Paleocene series is the body of

rock that was formed during the Paleocene

epoch.

A system is the most commonly used time-

stratigraphic unit because it represents a

 

significant and recognizable interval of geologic -------------------------------------------------------------- history, and it can be correlated with other 1250. Which one of the following terms is systems around the world based on their fossil used to describe an erosion surface cut into content and magnetic polarity. A system also metamorphic rocks that is covered by has a relatively large extent and thickness, sedimentary rocks? making it easier to map and study than smaller a) Stratigraphic break. units such as series or stages. b) Guide fossil. -------------------------------------------------------------- c) Geologic anomaly. 1249. According to the principle of fossil d) Nonconformity. succession: e) Sedimentary facies. a) A dike is older than the sedimentary rock it cuts through. Feedback: A nonconformity is a type of b) Time-stratigraphic units are defined by unconformity, which is a break or gap in the rock type. geologic record resulting from erosion or non- c) Fossil assemblages succeed one another deposition or both. An unconformity separates in a regular and predictable order. younger rocks from older rocks, indicating that d) A marine regression takes place when the some part of the geologic history is missing. A sea rises and invades a continent. nonconformity occurs when an erosion surface e) The geologic column and time scale are is cut into igneous or metamorphic rocks that based on the theory of evolution. are overlain by sedimentary rocks. This means that the igneous or metamorphic rocks were Feedback: According to the principle of fossil exposed at the Earth’s surface and eroded succession, also known as the law of faunal before the sedimentary rocks were deposited succession, different fossil species appear and on top of them. A nonconformity represents a disappear in a predictable sequence in significant time gap between the formation of sedimentary rocks. This means that the the older and younger rocks. different types of fossils that are found in rocks of different ages reflect the changes in life forms

that occurred through geologic time. The

principle of fossil succession allows geologists

to correlate rocks of different regions and

establish a relative time scale for the Earth’s history. The principle of fossil succession was

first recognized by William Smith, an English

engineer and geologist, in the early 19th

century. He observed that the same kinds of

 

fossils were always found in the same order in -------------------------------------------------------------- the rock layers, and that they were different 1251. The principle of inclusions holds that: from those found in older or younger layers. a) All aspects of the fossil record are The principle of fossil succession also implies important in deciphering Earth history. that fossils are indicators of their environment and climate, as different organisms have

260

b) Walter’s law applies only to conformable Feedback: The principle of superposition

sequences of strata. states that in an undisturbed sequence of

c) Fragments in a layer of rock are older than sedimentary rocks, the oldest layer is at the

the layer itself. bottom and the youngest layer is at the top. This

d) An eon is made up of two or more eras. principle is based on the observation that

e) Concurrent range zones are useful in time- sediments are deposited horizontally or nearly

stratigraphic correlation. horizontally, and that younger sediments are

deposited on top of older ones. Therefore, by

Feedback: This is the definition of the principle examining the vertical order of rock layers,

of inclusions, which states that any rock geologists can infer their relative ages, meaning

fragments or inclusions found in another rock which ones are older or younger than others.

are older than the rock that contains them. This The principle of superposition is one of the most

principle is based on the logic that the important principles of stratigraphy, which is the

inclusions must have existed before they were study of the arrangement and sequence of rock

incorporated into the host rock. The principle of layers. inclusions can be used to determine the relative

ages of rocks and their environments of

formation.

 

--------------------------------------------------------------

1254. The geologic column and relative

-------------------------------------------------------------- geologic time scale were established by the

1252. A group is a lithostratigraphic unit made 1840s based on:

up of: a) The theory of evolution.

a) At least three periods. b) The principle of unconformities. b) Four systems. c) Superposition and faunal succession. c) A disconformity and a nonconformity. d) Lithostratigraphic biozones. d) Biozones and members. e) The rate of radioactive decay. e) Two or more formations.

Feedback: These are two of the most important

Feedback: A group is a lithostratigraphic unit principles of stratigraphy, which is the study of

that consists of a series of related formations the arrangement and sequence of rock layers.

that have been classified together to form a The principle of superposition states that in an

group. A formation is the primary unit of undisturbed sequence of sedimentary rocks,

lithostratigraphy, which is the element of the oldest layer is at the bottom and the

stratigraphy that deals with the description and youngest layer is at the top. The principle of

nomenclature of the rocks of the Earth based faunal succession, also known as the law of

on their lithology and their stratigraphic fossil succession, states that different fossil

relations. A formation is a body of rock that is species appear and disappear in a predictable

defined and recognized on the basis of its order in sedimentary rocks, and that the same

lithologic properties or combination of lithologic kinds of fossils are always found in the same

properties and stratigraphic relations. A group order in the rock layers. These principles were

may sometimes be combined into supergroups, first recognized by William Smith, an English

which are larger lithostratigraphic units. engineer and geologist. He also coined the term

-------------------------------------------------------------- geologic column to describe the vertical

1253. Geologists use the principle of succession of rock strata and their

superposition to determine: corresponding fossils. By correlating the strata

a) How long ago a fossil organism lived. and fossils from different regions, Smith and

b) The duration of a marine regression. other geologists were able to establish a

c) Absolute ages for geologic events. relative geologic time scale that divided Earth’s

d) Whether fossil remains have been altered. history into major units based on their

e) The relative ages of rocks in a vertical characteristic fossils. The relative geologic time

sequence. scale does not assign numerical ages to the

 

261

rock layers or events, but only indicates their a) Stromatolite. order and duration relative to each other. b) Greenstone belt. -------------------------------------------------------------- c) Craton. 1255. Which one of the following is a trace d) Black smoker.

fossil? e) Komatiite.

a) Clam shell.

b) Dinosaur bone. Feedback: A craton is the ancient, stable part c) Worm burrow. of a continent that is composed of a shield and

d) Disconformity. a platform. A shield is the exposed part of the

e) Biozone. craton, where the basement rock is visible at

the surface. A platform is the covered part of the

Feedback: A worm burrow is an example of a craton, where the basement rock is overlain by

trace fossil, which is a fossil record of biological younger sedimentary rocks. A craton has a

activity but not the preserved remains of the thick crust and a deep lithospheric root that

plant or animal itself. Trace fossils contrast with extends into the mantle. A craton is resistant to

body fossils, which are the fossilized remains of tectonic deformation and has often survived

parts of organisms’ bodies, usually altered by cycles of merging and rifting of continents.

later chemical activity or mineralization. A worm Archon, proton, and tecton are terms used to

burrow is a type of trace fossil that shows the classify cratons based on the age and thermal

activity of a worm or a similar organism that dug history of their basement rocks. into the substrate, such as sediment, soil, or

rock. A worm burrow may consist of an

impression or a cast of the tunnel or cavity

created by the worm. A worm burrow may also

contain fecal pellets or other organic matter

produced by the worm. A worm burrow can

provide information about the behavior,

ecology, and environment of the worm and its

substrate.

 

--------------------------------------------------------------

1258. The origin of life from nonliving matter

is known as:

a) Outgassing. b) Abiogenesis. c) Cratonization. d) Biotic accretion. e) Polymerization.

 

-------------------------------------------------------------- Feedback: Abiogenesis is the natural process 1256. Ultramafic lava flows (komatiites) are by which life has arisen from non-living matter, found mostly in: such as simple organic compounds. a) Sandstone deposits of passive continental Abiogenesis proposes that the first life-forms margins. generated were simple and gradually became b) Banded iron formations. increasingly complex. Biogenesis, in which life c) The lower volcanic units in greenstone is derived from the reproduction of other life, belts. was presumably preceded by abiogenesis. d) Pyroclasticgneiss rift deposits. e) Cenozoic volcanic deposits.

Feedback: Ultramafic lava flows, also known as komatiites, are typically found in the lower

volcanic units of greenstone belts. Greenstone

belts are geological formations that contain a

variety of volcanic and sedimentary rocks, and

they are often associated with ancient

continental shields. Komatiites are known for

their exceptionally high magnesium content --------------------------------------------------------------

and are believed to have been more common 1259. Photochemical dissociation is a in the Archean Eon but are rare in modern process whereby: geological formations. a) Plants synthesize organic molecules. -------------------------------------------------------------- b) Carbon dioxide forms as a metabolic waste 1257. The ancient, stable part of a continent product of animal respiration.

made up of a shield and platform is called a:

262

c) Continents grow along their margins by e) Green because they contain the minerals

accretion. chlorite and epidote.

d) Gases emitted from Earth’s interior release

methane and ammonia into the Feedback: Granite-gneiss complexes are atmosphere. common in Archean terrains and are often

e) Water molecules are disrupted to yield associated with ancient continental crust.

hydrogen and oxygen. These rocks have undergone extensive

metamorphism and are characteristic of the

Feedback: Photochemical dissociation is a Archean Eon. process in which the energy from sunlight is --------------------------------------------------------------

used to break apart water molecules (H2O) into 1262. Many scientists think that the first self-their constituent elements, hydrogen (H) and replicating system was a(n): oxygen (O). This process can occur in the a) ATP cell. upper atmosphere, particularly in the presence b) Autotroph. of ultraviolet (UV) radiation from the Sun. The c) Proteinoid. dissociation of water into hydrogen and oxygen d) RNA molecule. is an important step in understanding the e) Stromatolite. evolution of Earth's atmosphere and the

formation of molecules that contribute to its Feedback: Many scientists believe that the first composition. self-replicating system may have been an RNA

molecule, as RNA can both store genetic

information and catalyze chemical reactions,

similar to the functions of DNA and proteins.

This hypothesis is part of the RNA world

hypothesis, which suggests that RNA-based

life forms existed before DNA-based life forms.

 

--------------------------------------------------------------

1260. Stromatolites are produced by

cyanobacteria which is also known as:

a) Blue-green algae.

b) Eukaryotic cells.

c) Black smokers.

d) Heterotrophs.

e) Polymers.

Feedback: Stromatolites are layered structures created by the growth of cyanobacteria, often

 

referred to as blue-green algae. These ancient -------------------------------------------------------------- microbial communities played a significant role 1263. Which one of the following sequences in Earth's early history and the development of of geologic time designations is in the the atmosphere. correct order from oldest to youngest? a) Archean-Phanerozoic-Proterozoic. b) Proterozoic-Phanerozoic-Archean. c) Phanerozoic-Archean-Proterozoic. d) Archean-Proterozoic-Phanerozoic. e) Proterozoic-Archean-Phanerozoic.

Feedback: This sequence represents the major divisions of Earth's history, with the

Archean being the oldest and the Phanerozoic

 

1261. Granite-gneiss complexes are: years ago. During the Archean, the Earth's a) The most widespread Archean-age rocks. crust began to form, and the first continents and b) Found at oceanic spreading ridges. oceans appeared. It's a time when life was just c) Most likely turbidite deposits. beginning to emerge in the form of simple, d) Noted for their fossil plants and animals. single-celled organisms. -------------------------------------------------------------- Archean: This is the oldest eon in Earth's history, ranging from about 4 billion to 2.5 billion being the most recent.

 

263

Proterozoic: Following the Archean, the Earth's crust and mantle. Greenstone belts are

Proterozoic eon spans from about 2.5 billion to also important economic resources, as they

541 million years ago. This eon saw the often contain ore deposits of valuable metals.

development of more complex life forms,

including the first multicellular organisms. It also

includes important events like the formation of

supercontinents and the first appearance of

oxygen in the atmosphere.

Phanerozoic: The Phanerozoic eon is the most recent eon, covering the last 541 million years

up to the present day. It's characterized by the

proliferation of complex life forms, including the

rise and fall of the dinosaurs, the evolution of

mammals, and the appearance of humans. It's

also when we find the majority of the fossil --------------------------------------------------------------

record. 1265. The exposed part of the craton in North -------------------------------------------------------------- America is called the: 1264. The origin of greenstone belts is not a) Canadian shield.

fully resolved, but many geologists think that b) Wyoming province. some of them formed in: c) Adirondack terrane.

a) Continental shelf environments. d) Michigan basin. b) Backarc marginal basins. e) Midcontinent platform. c) Carbonate-evaporite depositional areas. d) Transform boundary shear zones. Feedback: The exposed part of the craton in e) River floodplain environments. North America is known as the Canadian

Shield. It is a large geological shield that covers

Feedback: Greenstone belts are zones of a significant portion of Canada and parts of the

variably metamorphosed mafic to ultramafic northern United States. volcanic sequences with associated

sedimentary rocks that occur within Archaean

and Proterozoic cratons between granite and

gneiss bodies. The name comes from the green

hue imparted by the color of the metamorphic

minerals within the mafic rocks: the typical

green minerals are chlorite, actinolite, and other

green amphiboles. Greenstone belts also often

contain ore deposits of gold, silver, copper, zinc

and lead. --------------------------------------------------------------

There are two main hypotheses for the 1266. The widely accepted theory explaining formation of greenstone belts: the origin of eukaryotic cells holds that these

Backarc basin hypothesis: Greenstone belts cells formed by: formed in backarc basins, which are small a) Endosymbiosis. ocean basins that form behind volcanic island b) Parthenogenesis. arcs. Backarc basins are formed by the c) Binary fission. extension of the crust behind an island arc as it d) Pangenesis. moves over a subduction zone. e) Autotrophism. Oceanic plateau hypothesis: Greenstone belts formed on oceanic plateaus, which are Feedback: According to the endosymbiotic large, elevated regions of the ocean floor. theory, eukaryotic cells evolved through a

Oceanic plateaus are thought to form by process of endosymbiosis, where smaller

plumes of hot mantle material that rise through prokaryotic cells were engulfed by larger

the crust and cause it to melt. prokaryotic cells and eventually became

The backarc basin hypothesis is the more organelles within the host cell. This theory

widely accepted hypothesis for the formation of explains the presence of organelles like

greenstone belts. This is because greenstone mitochondria and chloroplasts in eukaryotic

belts are often found in association with other cells, which are believed to have originated

geological features that are associated with from free-living bacteria that were incorporated

backarc basins, such as ophiolites and island into ancestral eukaryotic cells. arc volcanics. --------------------------------------------------------------

Greenstone belts are important geological 1267. Cells with a membrane-bounded features because they provide a window into nucleus and internal structures called

the early Earth. The rocks in greenstone belts organelles are called cells: are some of the oldest rocks on Earth, and they a) Komatiitic. contain a wealth of information about the early b) Endosymbiotic.

264

c) Porphyritic. 1270. A large landmass composed mostly of d) Aphanitic. Greenland and North America that evolved

e) Eukaryotic. during the Proterozoic is called:

a) Grenvillia.

Feedback: Eukaryotic cells are characterized b) Ediacara. by having a membrane-bounded nucleus and c) Laurentia. internal structures called organelles, which d) Pannotia. distinguish them from prokaryotic cells like e) Romania. bacteria.

Feedback: Laurentia is a large landmass that included parts of what is now Greenland and

North America. It played a significant role in the

geological history of the Proterozoic and later

became part of the supercontinent Pangaea.

 

--------------------------------------------------------------

1268. The Mesoproterozoic of Laurentia was

a time of:

a) Widespread glaciation.

b) Origin of animals with skeletons.

c) Igneous activity unrelated to orogenic

activity.

d) Origin of the oldest known greenstone

belts.

e) Formation of Pangaea.

Feedback: During the Mesoproterozoic era in Laurentia, there was widespread igneous

activity that was unrelated to orogenic

(mountain-building) activity. This era was --------------------------------------------------------------

 

-------------------------------------------------------------- Granite-gneiss complex. a) 1269. One type of Proterozoic rock that b) Turbidite deposit. indicates some free oxygen was present in c) Ophiolite. the atmosphere is: d) and the formation of igneous rocks. of mantle rocks overlain by oceanic crust and deep sea sediments is a(n): characterized by various geological processes 1271. A sequence of rocks on land made up

 

a) Continental red bed. Continental red beds. e) Supercycle. b) Carbon- conglomerate assemblages. c) Ultramafic lava flows. Feedback: An ophiolite is a sequence of rocks d) Wilson cycle deposits. that includes mantle rocks, oceanic crust, and e) Prokaryotic accumulates. deep-sea sediments. It provides a unique

 

Feedback: window into the Earth's oceanic lithosphere and Continental red beds are is often found on land as a result of tectonic sedimentary rocks that are typically red in color processes that have brought oceanic material due to the presence of oxidized iron (iron oxide to the Earth's surface. Ophiolites are valuable or rust). The formation of these red beds for studying the composition and structure of suggests that free oxygen (O 2 ) was present in oceanic crust and the processes associated the atmosphere because the iron in these rocks with plate tectonics. would have only oxidized in the presence of

oxygen. Therefore, the presence of continental

red beds in the Proterozoic indicates the

presence of some free oxygen in the Earth's

atmosphere during that time.

 

-------------------------------------------------------------- --------------------------------------------------------------

 

265

1272. oceanic plate or a continental plate. This The oldest known animal fossils are process is a key mechanism in plate tectonics tectonic plate, which can be either another

found in the ________ fauna of Australia.

a) and often leads to the formation of deep-sea Ediacaran.

b) trenches, volcanic arcs, and earthquakes. Pannotian.

c) -------------------------------------------------------------- Wilsonian.

d) 1275. Which one of the following was a Stromatolinian.

e) supercontinent during the Proterozoic? Grenvillian.

a) Pangaea.

Feedback: b) Rodinia The Ediacaran fauna, found in the Ediacaran Period of the late Precambrian, c) Ediacara. contains some of the oldest known animal d) Laurasia. fossils. These fossils represent early and often e) Mesoamerica. enigmatic multicellular life forms that predate

the Cambrian explosion, a significant period of Feedback: Rodinia was a supercontinent that

biological diversification in Earth's history. existed during the Proterozoic eon,

approximately 1.3 billion to 750 million years

ago. It was one of the Earth's earliest

supercontinents, and its formation and breakup

played a significant role in the geological history

of our planet.

 

--------------------------------------------------------------

1273. Columnar masses of rock resulting

from the activities of cyanobacteria (blue-

green algae) are:

a) Heterotrophs.

b) Endosymbionts.

c) Orogens.

e) -------------------------------------------------------------- d) Stromatolites.

Trilobites.

 

of rock that form as a result of the activities of Cyclothem. b) Mobile belt. cyanobacteria (blue-green algae) and other c) Platform. microorganisms. These structures are some of d) Feedback: mountain building is a(n): Stromatolites are columnar masses a) 1276. An elongated area marking the site of the earliest known evidence of life on Earth and Shield. e) Craton. can be found in various geological formations.

Feedback: An elongated area marking the site of mountain building is referred to as a mobile

belt. This term is often used to describe regions

where tectonic forces have caused significant

deformation and uplift, leading to the formation

of mountain ranges or other geological

structures.

 

--------------------------------------------------------------

1274. The sliding of oceanic lithosphere

beneath a continent or island arc is called:

a) Rotation.

b) Tension.

c) Subduction.

d) Polar wandering.

Feedback: Subduction is the process where oceanic lithosphere slides beneath another --------------------------------------------------------------

266

1277. During which period did extensive 1279. A major transgressive–regressive

continental glaciation of the Gondwana cycle bounded by craton-wide

continent occur? unconformities is a(n):

a) Cambrian. a) Biostratigraphic unit. b) Silurian. b) Cratonic sequence. c) Devonian. c) Orogeny. d) Carboniferous. d) Shallow sea. e) Permian. e) Cyclothem.

Feedback: Extensive continental glaciation of Feedback: A major transgressive-regressive the Gondwana continent occurred during the cycle bounded by craton-wide unconformities is

Carboniferous period. This period, also known commonly referred to as a cratonic sequence.

as the Carboniferous period, was characterized These sequences represent significant

by the presence of vast swamp forests that geological events in which sea levels rise

eventually led to the formation of coal deposits, (transgressive phase) and then fall (regressive

and it experienced multiple glaciation events in phase), leading to the deposition of

the Southern Hemisphere as part of the larger sedimentary layers and the formation of

ice age cycle. unconformities between them.

--------------------------------------------------------------

1280. The economically valuable deposit in a

cyclothem is:

a) Gravel. b) Metallic ore. c) Coal. d) Carbonates. e) Evaporates.

Feedback: In a cyclothem, the economically valuable deposit is often coal. These cyclical

sedimentary sequences can contain alternating

-------------------------------------------------------------- layers of marine and nonmarine sediments,

1278. Repetitive sedimentary sequences of with coal beds typically forming in the

alternating marine and nonmarine nonmarine (terrestrial) environments. Coal is a

sedimentary rocks are: valuable resource for energy production and

a) Cyclothems. has been a significant economic deposit in

b) Reefs. various regions. c) Orogenies.

d) Evaporates.

e) Tillites.

Feedback: Repetitive sedimentary sequences of alternating marine and nonmarine

sedimentary rocks are called cyclothems.

These sequences often reflect changes in sea

level and environmental conditions over time

and are commonly associated with the

Carboniferous period's sedimentary record. --------------------------------------------------------------

1281. What type of invertebrates dominated

the Ordovician invertebrate community?

a) Epifloral planktonic primary producers. b) Infaunal nektonic carnivores. c) Infaunal benthic sessile suspension

feeders.

d) Epifaunal benthic mobile suspension

feeders.

e) Epifaunal, benthic, sessile, suspension

feeders.

Feedback: These organisms lived on the ocean floor (benthic), were attached and did not

move (sessile), and fed by capturing

suspended food particles from the water

-------------------------------------------------------------- (suspension feeders). This type of lifestyle was

 

267

common among many marine invertebrates c) Diatoms. during the Ordovician period. d) Dinoflagellates. -------------------------------------------------------------- e) Graptolites. 1282. Labyrinthodonts are:

a) Plants. Feedback: Acritarchs are a diverse group of b) Fish. organic-walled phytoplankton that left behind

c) Amphibians. fossilized organic cysts. They were a significant

d) Reptiles. part of the Paleozoic phytoplankton community

e) None of the previous answers. and are commonly used in biostratigraphy to

date sedimentary rocks from that era.

Feedback: Labyrinthodonts are an extinct group of amphibians that lived from the

Devonian to the Triassic periods, about 419 to

201 million years ago. They are considered to

be the earliest tetrapod vertebrates, meaning

they had four limbs and could move on land.

They are named after their complex teeth,

which had folded enamel surfaces that

resembled a labyrinth. They ranged in size from

small to large, and had lizard-like or crocodile-

like bodies. Some of them had external gills,

while others had lungs. They were mostly

carnivorous, feeding on fish, insects, and other

animals.

--------------------------------------------------------------

1283. Organisms that manufacture their own

food are:

a) Autotrophs.

b) Herbivores. --------------------------------------------------------------

c) Benthos. 1285. Which group of planktonic d) Epifaunal. invertebrates that were especially abundant

e) None of the previous answers. during the Ordovician and Silurian periods

are excellent guide fossils?

Feedback: Organisms that manufacture their a) Brachiopods. own food through processes like b) Cephalopods. photosynthesis or chemosynthesis are called c) Fusulinids. autotrophs. They can produce organic d) Graptolites. compounds and energy from inorganic e) Trilobites. substances, often using sunlight as an energy

source. This ability to produce their own food Feedback: Graptolites are excellent guide sets them apart from heterotrophs, which rely fossils, especially during the Ordovician and

on consuming other organisms for their Silurian periods. These planktonic colonial

nutrition. organisms left behind well-preserved fossils

that are widely used for biostratigraphy and

correlating rock layers.

 

-------------------------------------------------------------- --------------------------------------------------------------

1284. Brachiopods are: The major organic-walled 1286.

phytoplankton group of the Paleozoic Era a) Benthic mobile carnivores. was: Benthic mobile scavengers. b)

a) Acritarchs. c) Benthic suspension feeders. b) Nektonic carnivore-scavengers. Coccolithophorids. d)

268

e) Planktonic primary producers. Feedback: An exoskeleton offers several

advantages, including preventing desiccation

Feedback: Brachiopods are marine (drying out), protection against environmental invertebrates characterized by their two- factors like UV radiation, serving as a defense

shelled, hinged shells that resemble those of against predators, and providing attachment

clams but are not closely related. They are filter sites for muscles. feeders, using a lophophore (a specialized --------------------------------------------------------------

feeding organ) to capture tiny food particles 1289. Mass extinctions occurred at, or near from the water. Brachiopods are benthic the end, of which three periods? organisms, meaning they live on the ocean a) Cambrian, Ordovician, Permian. floor, and they are not mobile like some other b) Cambrian, Silurian, Devonian. marine animals. Their unique shell morphology c) Ordovician, Devonian, Permian. and ecological role make them important guide d) Silurian, Devonian, Permian. fossils in the study of Earth's history, as their e) Cambrian, Devonian, Permian. presence can help determine the age of

sedimentary rocks in which they are found. Feedback: Mass extinctions indeed occurred

at or near the end of these three periods in

Earth's history. These extinction events were

significant and had a profound impact on the

evolution of life on our planet. The Ordovician-

Silurian extinction, Devonian extinction, and

Permian-Triassic extinction are among the

major mass extinctions in Earth's history, each

associated with different environmental and

biological factors. These events shaped the

course of evolution and the diversity of life on

-------------------------------------------------------------- Earth. 1287. The earliest reef-like structures were

constructed by:

a) Bryozoans.

b) Mollusks.

c) Archaeocyathids.

d) Sponges.

e) Corals.

Feedback: These ancient reef-like structures were constructed by a group of organisms --------------------------------------------------------------

known as archaeocyathids, which were 1290. Based on similarity of embryo cell sponge-like animals that lived during the early division, which invertebrate phylum is most

Cambrian period. These structures are among closely allied with the chordates? the earliest examples of reefs in the fossil a) Mollusca. record. b) Echinodermata.

c) Porifera. d) Annelida. e) Arthropoda.

Feedback: The invertebrate phylum most closely allied with the chordates based on

similarity of embryo cell division is

Echinodermata. This similarity in embryonic

development is a key piece of evidence for their

-------------------------------------------------------------- evolutionary relationship. 1288. -------------------------------------------------------------- An exoskeleton is advantageous

because it: 1291. The age of the Burgess Shale is:

a) Prevents drying out in an intertidal a) Cambrian.

environment. b) Ordovician.

b) Provides protection against ultraviolet c) Silurian.

radiation. d) Devonian.

c) Provides protection against predators. e) Mississippian. d) Provides attachment sites for development

of strong muscles. Feedback: The Burgess Shale is a famous

e) fossil deposit located in the Canadian Rockies All of the previous answers.

and dates back to the Cambrian period,

 

269

specifically the middle Cambrian continental blocks, and these are considered (approximately 508 million years ago). It the precursors to the modern continents. The

contains exceptionally well-preserved fossils of six major continental blocks within Pannotia

various early marine organisms, providing were: valuable insights into the diversity of life during Laurentia: This would later become North that time. America and parts of northern Europe.

Baltica: This would become parts of northern Europe, including Scandinavia and the Baltic

region.

Siberia: The core of what is now the Siberian landmass.

Gondwana: This supercontinent included the landmasses that would become South

America, Africa, Antarctica, India, Australia,

and parts of Asia.

Kazakhstania: This landmass is now part of Central Asia.

-------------------------------------------------------------- South China: The area that would become 1292. The three invertebrate groups that southeastern China.

comprised the majority of Cambrian These continents would go through further

skeletonized life were: cycles of fragmentation and collision,

a) Trilobites, archaeocyathids, brachiopods. eventually leading to the configuration of the

b) Echinoderms, corals, bryozoans. continents we recognize today. c) Brachiopods, archaeocyathids, corals.

d) Trilobites, echinoderms, corals.

e) Trilobites, brachiopods, corals.

Feedback: Trilobites were a group of arthropods that lived in the Cambrian period.

They were characterized by their segmented

bodies, which were divided into three parts: the

head, thorax, and abdomen.

Trilobites had a variety of body shapes and sizes, and they were some of the most diverse

animals of the Cambrian period.

Archaeocyathids were a group of sponges --------------------------------------------------------------

that lived in the Cambrian period. They were 1294. The ____ and ____ were times of characterized by their cup-shaped skeletons, major reef building. which were made of calcium carbonate. a) Cambrian, Ordovician. Archaeocyathids were some of the first animals b) Ordovician, Silurian. to develop skeletons, and they played an c) Silurian, Devonian. important role in building reefs in the Cambrian d) Devonian, Mississippian. period. e) Mississippian, Pennsylvanian. Brachiopods are a group of marine invertebrates that have been around for over Feedback: The Silurian Period was a time of

500 million years. They are characterized by extensive reef development. The most

their bivalve shells, which are hinged together important reef builders were the tabulate and

like a clamshell. Brachiopods were very diverse rugose corals, which appeared in the

in the Cambrian period, and they played an Ordovician and became abundant and diverse

important role in the Cambrian ecosystem. in the Silurian. The Devonian Period is

-------------------------------------------------------------- sometimes called the “Age of Fishes” because

1293. of the great diversity and abundance of fish that How many major continents were there

at the beginning of the Cambrian? evolved during this time. It is also known as the

a) 3 continents “Age of Reefs” because of the spectacular reef

b) 4 continents complexes that developed in various parts of

c) the world. The main reef builders were again 5 continents

d) 6 continents the tabulate and rugose corals, the

e) 7 continents stromatoporoids, and the calcareous algae, but

they were joined by new groups such as the

Feedback: During the beginning of the bryozoans, which were colonial animals with

Cambrian period, approximately 541 million calcified skeletons, and the chaetetids, which

years ago, the Earth's landmasses were were sponge-like animals with calcareous

grouped together in a supercontinent known as tubes. "Pannotia." Pannotia consisted of several --------------------------------------------------------------

270

1295. Which of the following groups did anatomical features, including a more

amphibians evolve from? advanced jaw structure and teeth compared to

a) Coelacanths. earlier reptiles. This group represents a

b) Ray-finned fish. transitional phase in reptile evolution toward the

c) Lobe-finned fish. development of mammalian characteristics.

d) Pelycosaurs. Over time, some therapsids evolved into early

e) Therapsids. mammals, eventually leading to the diverse

range of mammals we have today. This

Feedback: Amphibians evolved from lobe- transition is significant in the history of life on

finned fish. This transition is a significant event Earth as it marked the emergence of mammals

in the history of vertebrate evolution, as it as a distinct group. marked the shift from aquatic life to terrestrial --------------------------------------------------------------

life in early vertebrates. 1298. An organism must possess which of

the following during at least part of its life

cycle to be classified a chordate?

a) Notochord, dorsal solid nerve cord, lungs. b) Vertebrae, dorsal hollow nerve cord, gill

slits.

c) Vertebrae, dorsal hollow nerve cord, lungs. d) Notochord, ventral solid nerve cord, lungs. e) Notochord, dorsal hollow nerve cord, gill

slits.

Feedback: Chordates are a phylum of animals

-------------------------------------------------------------- that share four key features during at least part

1296. of their life cycle: a notochord, a dorsal hollow Which plant group first successfully

invaded land? nerve cord, pharyngeal slits, and a post-anal

a) tail. Seedless vascular.

b) Gymnosperms; --------------------------------------------------------------

c) Naked seed bearing. 1299. The Age of Fish is which period? d) a) Cambrian. Angiosperms.

e) Flowering. b) Silurian.

c) Devonian.

Feedback: The seedless vascular plants were d) Pennsylvanian. the first group of plants to successfully invade e) Permian. land. These plants include early forms like ferns

and horsetails and played a crucial role in Feedback: The Age of Fish corresponds to the paving the way for the evolution of more Devonian period. During the Devonian, which is

advanced plant groups like gymnosperms and often called the "Age of Fish," fish diversity and

angiosperms. abundance increased significantly. This period

saw the evolution of various types of jawed fish,

including the first appearance of some groups

of bony fish and early sharks. It was a pivotal

time in the history of vertebrate evolution as fish

adapted to various aquatic environments,

leading to the development of more advanced

forms of fish. This period laid the foundation for

the subsequent evolution of tetrapods (four-

limbed vertebrates) and terrestrial life.

 

--------------------------------------------------------------

1297. Which reptile group gave rise to the

mammals?

a) Labyrinthodonts.

b) Acanthodians.

c) Pelycosaurs.

d) Protothyrids.

 

Feedback: 1300. Which evolutionary innovation allowed Therapsids are a group of reptiles reptiles to colonize all of the land? that are believed to have given rise to a) e) Therapsids. --------------------------------------------------------------

Tear ducts.

mammals. They are characterized by certain b) Additional bones in the jaw.

271

c) The middle-ear bones. 1303. Which algal group was the probable d) An egg that contained a food-and-waste ancestor to vascular plants?

sac and surrounded the embryo in a fluid- a) Yellow. filled sac. b) Blue-green.

e) Limbs and a backbone capable of c) Red.

supporting the animals on land. d) Brown.

e) Green.

Feedback: This innovation is associated with the development of the amniotic egg, which Feedback: Green algae, specifically the group allowed reptiles to reproduce successfully on known as charophytes, is believed to be the

land. The amniotic egg is often referred to as closest living relative to land plants (vascular

the "terrestrial egg" because it has several plants). This group shares several important

adaptations that enable it to thrive in a characteristics with land plants and is thought

terrestrial environment. These adaptations to have given rise to the first terrestrial plants.

include a waterproof shell, membranes for Green algae are considered a key step in the

protection and nutrient exchange, and an evolutionary transition from aquatic algae to

enclosed fluid-filled sac that helps prevent land plants. desiccation (drying out) and provides a stable

environment for the developing embryo.

--------------------------------------------------------------

1301. Pelycosaurs are:

a) Jawless fish.

b) Jawed armored fish.

c) Reptiles.

d) Amphibians.

e) Plants.

 

Feedback: Pelycosaurs were a group of early -------------------------------------------------------------- reptiles that lived during the Paleozoic Era. 1304. In which period were amphibians and They are known for their distinctive sail-like seedless vascular plants most abundant? structures on their backs, which were likely a) Permian. used for thermoregulation. Pelycosaurs are not b) Pennsylvanian. fish, amphibians, or plants; they are reptiles that c) Mississippian. played a significant role in the early evolution of d) Silurian. terrestrial vertebrates. e) Cambrian.

Feedback: The Pennsylvanian period, part of the Carboniferous period, was characterized by

lush swampy environments and an abundance

of amphibians and seedless vascular plants.

This period saw the development of extensive

coal-forming swamps due to the proliferation of

 

1302. The Cenozoic Era consists of two organisms. periods: the ______ and _______ a) Paleogene and Neogene. b) Permian and Cretaceous. c) -------------------------------------------------------------- a time when both terrestrial and aquatic ecosystems were dominated by these plant life, which later became fossil fuels. It was

Proterozoic and Archean.

d) Mesozoic and Triassic.

e) Miocene and Eocene.

Feedback: The Cenozoic Era consists of two periods: the Paleogene (66 million to 23 million

years ago) and the Neogene (23 million to 2.6 --------------------------------------------------------------

million years ago). These two periods replaced 1305. The discovery of Tiktaalik roseae is the older term Tertiary, which is no longer used significant because it is: by the International Commission on a) The ancestor of modern reptiles. Stratigraphy. The Cenozoic Era also includes b) An intermediate between lobe-finned fish the Quaternary Period (2.6 million years ago to and amphibians. the present), which is sometimes considered as c) The first vascular land plant. a sub-period of the Neogene. d) The “missing-link” between amphibians -------------------------------------------------------------- and reptiles.

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e) The oldest known fish. such as coral reefs, open oceans, polar

regions, and freshwater. Some dinoflagellates

Feedback: Tiktaalik roseae is an important are symbiotic with corals and other animals,

fossil discovery because it represents a providing them with organic carbon and

transitional form between lobe-finned fish and oxygen. Some dinoflagellates are

early tetrapods (amphibians). It lived during the bioluminescent, producing light when late Devonian period and had features of both disturbed. Some dinoflagellates are also toxic,

fish and tetrapods, such as limb-like fins with causing harmful algal blooms or red tides that

joints, suggesting that it could support itself in can affect marine life and human health. shallow water and possibly move on land. This

fossil provides crucial insights into the evolution

of vertebrates from water to land and helps

bridge the gap between aquatic and terrestrial

life forms.

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1306. Triassic rifting between which two

continental landmasses initiated the

breakup of Pangaea?

a) India and Australia.

b) Antarctica and India.

c) South America and Africa.

d) North America and Eurasia.

e) Laurasia and Gondwana.

--------------------------------------------------------------

Feedback: During the Triassic period, Laurasia 1308. What is the order geologic time scales and Gondwana began to rift apart, initiating the are divided (largest to smallest): breakup of the supercontinent Pangaea. This a) Epoch, Period, Era. process eventually led to the formation of the b) Era, Epoch, Period. modern continents. c) Period, Epoch, Era.

d) Era, Period, Epoch.

Feedback: The geological time scale is divided into larger units called Eras, each of which is

further subdivided into Periods, and each

Period is divided into Epochs. This hierarchical

structure helps geologists organize and

categorize Earth's history.

--------------------------------------------------------------

1309. Because of their rapid evolution and

nektonic lifestyle, the _____ are good guide

fossils.

a) Amphibians. b) Cephalopods.

-------------------------------------------------------------- c) Burrowing worms. 1307. Which of the following were common d) Saurischians.

during the Mesozoic, and are the major e) Bivalves. primary producers in the warm seas today?

a) Ammonoids. Feedback: Cephalopods, particularly b) Nautiloids. ammonites, are considered excellent guide

c) Coleoids. fossils because of several key factors: d) Dinoflagellates. Rapid Evolution: Ammonites underwent e) Rudists. relatively rapid evolutionary changes, resulting

in numerous species with distinct

Feedback: Dinoflagellates are a group of morphological characteristics. This rapid

unicellular algae that have two flagella and a evolution makes them useful for stratigraphic

cell wall made of cellulose plates. They were correlation and dating of rock layers. common during the Mesozoic era, especially in Abundance: Ammonites were once the Cretaceous period, when they formed large widespread and diverse in the world's oceans,

blooms that contributed to the formation of which means they left behind a rich fossil

chalk deposits. They are also the major primary record. Fossils of ammonites are often found in

producers in the warm seas today, where they sedimentary rocks, making them accessible for

account for about 40% of the marine study. photosynthesis. Dinoflagellates are diverse and Distinctive Shapes: Ammonites exhibit a wide adaptable, and can live in various habitats, variety of coiled shell shapes and

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ornamentation, making it relatively easy to Feedback: Eupantotheres were an early group differentiate between species based on their of mammals that are considered to be the

shell characteristics. This distinctiveness aids probable ancestors of placental and marsupial

in their identification and use as guide fossils. mammals. This is a significant group in the

Stratigraphic Range: Ammonites existed from context of mammalian evolution because it

the Devonian period to the end of the represents a point in history where mammalian

Cretaceous period, spanning a significant reproductive strategies were diversifying.

portion of geologic time. This long stratigraphic Placental mammals, like humans, have a

range allows them to be used for dating rocks placenta that nourishes developing embryos in

from a wide range of time periods. the womb, while marsupials, like kangaroos,

Overall, the combination of rapid evolution, give birth to relatively undeveloped young,

abundant fossils, distinctive features, and a which then continue to develop outside the

long stratigraphic range makes cephalopods, womb in a pouch. Eupantotheres played a role

especially ammonites, valuable for in the early evolution of these different

understanding Earth's geological history and reproductive strategies within the mammalian

correlating rock layers. lineage.

--------------------------------------------------------------

1312. The Himalayas formed when the plate

collided with the plate.

a) Farallon/Pacific. b) Nazca/Cacos. c) African/European. d) Indian/Asian. e) Australian/South American.

Feedback: The Himalayan mountain range was formed as a result of the ongoing collision

between the Indian Plate and the Eurasian

-------------------------------------------------------------- Plate. This collision, which began around 50

1310. Theropods were: million years ago and continues today, has led

a) Long-necked marine reptiles. to the uplift of the Himalayan mountains,

b) Egg-laying mammals. making them one of the most geologically

c) Bipedal, carnivorous dinosaurs. active and significant mountain ranges on

d) Dome-headed, herbivorous mammals. Earth. The convergence of these two tectonic

e) Flying reptiles. plates has caused the crust to thicken and fold,

resulting in the impressive topography of the

Feedback: Theropods were bipedal, Himalayas. carnivorous dinosaurs. These dinosaurs were

characterized by their two-legged stance, sharp

teeth, and predatory nature. They are perhaps

most famous for including some of the largest

and most well-known dinosaurs, such as

Tyrannosaurus rex and Velociraptor.

 

--------------------------------------------------------------

1313. The San Andreas Fault formed when

the North American plate overrode the:

a) Ouachita subduction zone. b) Zuni epeiric sea.

 

-------------------------------------------------------------- d) Pacific-Farallon ridge. e) c) Andes Mountains.

 

a) Probable ancestor of placental and Feedback: The San Andreas Fault formed as a marsupial mammals. result of the movement and interaction between b) 1311. Atlantic Coastal Plain. The eupantotheres were the:

 

c) Most dolphin-like of all ichthyosaurs. the North American plate and the Pacific- Largest of all sauropods. Farallon ridge, which is a divergent plate d) First vertebrate animals capable of flight. boundary. This interaction led to the e) Most diverse bivalve gymnosperms. development of this significant fault system in

 

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California. The San Andreas Fault is a materials older than about 50,000 years due to

transform fault boundary where the Pacific the decreasing amount of carbon-14 available

Plate and the North American Plate slide past for measurement. For older materials, other

each other horizontally. It marks the boundary dating methods like radiometric dating of

between these two major tectonic plates and is isotopes with longer half-lives are employed.

one of the most well-known and studied fault

systems in the world. The movement along the

San Andreas Fault has resulted in significant

seismic activity and is responsible for the

creation of much of California's mountainous

terrain. It's an excellent example of plate

tectonics in action and has been extensively

studied to understand the dynamics of plate

boundaries and the potential for earthquakes in

the region.

 

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1315. During the Cenozoic Era, Earth’s

temperature was highest during the:

a) Pleistocene. b) Pliocene. c) Eocene. d) Cretaceous. e) Neogene.

Feedback: During the Cenozoic Era, the Eocene epoch, which occurred approximately

56 to 34 million years ago, experienced some

of the highest global temperatures in Earth's

recent history. This period was characterized by

a greenhouse climate with elevated

temperatures and high levels of carbon dioxide

 

1314. Carbon dating is used on: tropical today. a) Organic samples. b) Minerals. c) Metamorphic rocks. d) -------------------------------------------------------------- of the Eocene epoch supported the growth of lush tropical rainforests in regions that are not (CO 2) in the atmosphere. The warm conditions

Igneous rocks.

Feedback: Carbon dating, also known as radiocarbon dating, is a widely used method for

determining the age of organic materials

containing carbon-14 isotopes. This technique

relies on the fact that carbon-14 is a radioactive

isotope with a known decay rate, and it's --------------------------------------------------------------

incorporated into living organisms through the 1316. One of the major components of the carbon cycle. When an organism dies, it stops Cenozoic marine invertebrate fauna was:

absorbing carbon-14, and the isotope starts to a) Foraminifera. decay. By measuring the remaining amount of b) Cetaceans. carbon-14 in a sample, scientists can estimate c) Proboscidians. how long it has been since the death of the d) Ungulates. organism, providing a way to date the sample. e) Ammonites. Carbon dating is particularly useful for dating

archaeological and geological samples that Feedback: Foraminifera are a major contain once-living materials, such as wood, component of the Cenozoic marine invertebrate

bone, shell, and plant remains. It's effective for fauna. These are single-celled organisms with

dating samples up to around 50,000 years old, calcium carbonate shells (tests) that make up a

making it a valuable tool for understanding the significant portion of marine microfossils. They

timing of events in Earth's recent history. It's are important for paleontologists and geologists

important to note that carbon dating has studying the Cenozoic Era because their

limitations and may not be suitable for dating fossilized remains are widely distributed and

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provide valuable information about the ancient Atlantic coastal plain, contributing to the

marine environments and climates. formation of its geological features.

 

--------------------------------------------------------------

1319. A fossil found over a large area

deposited within a short time period is ____.

a) A specimen interval. b) An index fossil. c) A time differential.

-------------------------------------------------------------- d) An indicator marker. 1317. Which one of the following has been

proposed to account for Pleistocene Feedback: An index fossil is a fossilized

extinctions? organism that is useful for dating and

a) correlating the strata in which it is found. It is Meteorite impact.

b) typically a species that had a wide geographic Climate change.

 

d) existence. When found in rock layers, it can be Migration of mammals from Australia. used as an indicator of the time period during c) distribution and a relatively short-lived Evolution of grasses.

e) Increased energy from the Sun.

which those rocks were deposited.

Feedback: The Pleistocene extinctions, often referred to as the Quaternary extinction event,

are believed to have been primarily driven by

climate change. During this period, there were

significant fluctuations in global climate,

including repeated glacial and interglacial

periods. These changes in climate led to shifts

in vegetation and available food resources for

animals, affecting ecosystems and causing the

extinction of many large mammal species.

 

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1320. Paleozoic is an example of ______. a) An epoch. b) An era. c) A period. d) An eon.

-------------------------------------------------------------- Feedback: Paleozoic is one of the three 1318. Most of the Cenozoic-age sediment on geological eras of the Phanerozoic Eon, which

the Atlantic coastal plain was eroded from covers the time span from 541 to 252 million

the: years ago. An epoch is a subdivision of a

a) Rocky Mountains. period, which is a subdivision of an era. An eon

b) Cascade Range. is the largest unit of geologic time,

c) Appalachian Mountains. encompassing several eras. d) Ozark Plateau. --------------------------------------------------------------

e) Farallon ridge. 1321. The Precambrian is the ________ time

span in Earth's history.

Feedback: Most of the Cenozoic-age sediment a) Youngest. on the Atlantic coastal plain was eroded from b) Latest. the Appalachian Mountains. Over millions of c) Earliest. years, weathering and erosion of the d) Middle. Appalachian Mountains supplied sediments

that were transported and deposited on the Feedback: The Precambrian is the earliest

time span in Earth's history. It represents the

 

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vast portion of Earth's history before the

Phanerozoic Eon, which includes the

Paleozoic, Mesozoic, and Cenozoic Eras with

their abundant fossil record. The Precambrian

encompasses approximately 4.6 billion years of

Earth's history, from the planet's formation to

the beginning of the Cambrian Period, when

complex life forms with hard parts started to

appear in the fossil record. This long span of

time is divided into several eons, eras, and

periods, but it's characterized by a scarcity of

well-preserved fossils compared to the later

Phanerozoic Eon.

 

--------------------------------------------------------------

1322. Earth today is in ______________.

a) Cenozoic era, Quaternary period,

Holocene epoch.

b) Precambrian epoch.

c) Devonian period, Quaternary era.

d) a) Bacteria, fish, birds, humans. Triassic interglacial.

b) Bacteria, birds, fish, humans.

Feedback: The Cenozoic era is the current c) Humans, birds, fish, bacteria. geological era and began approximately 66 d) Humans, fish, birds, bacteria. million years ago, following the end-Cretaceous

mass extinction event. It is often referred to as Feedback: Bacteria are the oldest and most the "Age of Mammals." The Quaternary period diverse group of living organisms on Earth.

is a subdivision of the Cenozoic era and They first appeared about 4 billion years ago,

encompasses the last 2.6 million years. It is soon after the formation of the planet. Fish are

known for repeated glaciations (ice ages) and the earliest vertebrate animals, evolving from

the appearance of humans. The Holocene aquatic invertebrates about 500 million years

epoch is the most recent epoch within the ago. Birds are the descendants of feathered

Quaternary period and represents the period of dinosaurs, which emerged about 150 million

relatively stable and warm climate during which years ago. Humans are the most recent group,

human civilization developed. belonging to the primates, which evolved from

-------------------------------------------------------------- mammalian ancestors about 65 million years

1323. ago. Absolute dating measures ________. a) -------------------------------------------------------------- The radioactive decay of material.

b) 1325. What percent of isotopes of U-238 The depth of the fossil relative to sea level.

c) would be remaining after 2 half-lives? Climate CO 2 concentration.

d) a) 100% The movement of tectonic plates.

b) 75%

Feedback: Absolute dating techniques, such c) 50% as radiometric dating, measure the radioactive d) 25% decay of certain isotopes in minerals to

determine the absolute age (in years) of rocks Feedback: After 2 half-lives, half of the and fossils. This method relies on the remaining U-238 isotopes will have decayed.

predictable decay rates of radioactive isotopes This means that 25% of the original U-238

and is widely used in geology and archaeology isotopes would be remaining. U-238 has a half-

to determine the age of geological formations life of approximately 4.468 billion years. After

and archaeological artifacts. It provides a one half-life, half of the original U-238 isotopes

numerical age estimate, unlike relative dating will have decayed, leaving 50%. After two half-

methods that only establish the relative order of lives, half of the remaining 50% will have

events. decayed, resulting in 25% remaining. This

-------------------------------------------------------------- pattern continues with each successive half-

1324. life. In what order do these appear in the

geologic record ( oldest to youngest)? --------------------------------------------------------------

1326. Trilobites are found in the ________. a) Cenozoic.

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b) Mesozoic. 1328. The radioactive decay of material can c) Paleozoic. be used to determine the age of fossils. This

d) Cretaceous. is called:

a) Fossil dating.

Feedback: Trilobites were ancient marine b) Complete dating. arthropods that lived primarily during the c) Relative dating. Paleozoic era, which is often referred to as the d) Absolute dating. "Age of Trilobites" due to their abundance and

diversity during this time. These creatures are Feedback: The radioactive decay of materials, known for their distinctive segmented such as isotopes found in minerals or fossils, is

exoskeletons, which made them excellent used in absolute dating methods to determine

candidates for fossilization. Fossils of trilobites the actual numerical age of rocks, fossils, or

are found in Paleozoic-aged sedimentary rocks archaeological artifacts. This contrasts with

around the world, providing valuable insights relative dating, which determines the order of

into the Earth's ancient oceans and events or objects in relation to one another but

ecosystems. Their fossils are important for does not provide specific numerical ages. understanding the history of life on Earth and

are often used as index fossils for dating rocks

from the Paleozoic era.

 

1327. Which of these is the best indication of -------------------------------------------------------------- the relative age of a rock layer? --------------------------------------------------------------

 

b) a) Index dating. other layers. b) Relative dating. c) The distance the layer extends over the c) Absolute dating. Earth. a) The thickness of the layer. a layer is older or younger from another is: The position of the layer compared to 1329. The method used when determining if

d) Fossil fractionation.

d) The chemical makeup of the layer.

Feedback: Relative dating is the method used

 

best indicated by its position in relation to other archaeological feature is older or younger than layers of rock. This principle is known as the Feedback: The relative age of a rock layer is to determine whether one geological or

another. It establishes the relative order of

Law of Superposition, which states that in an events or the sequence of deposition by

undisturbed sequence of sedimentary rocks, examining the position of rocks, fossils, or

the youngest rocks are at the top, and the artifacts in relation to one another within

oldest rocks are at the bottom. This allows stratigraphic layers. This method doesn't

geologists to determine the relative order of provide specific numerical ages but helps

rock layers and the events that occurred in geologists and archaeologists understand the

Earth's history. Other factors like thickness, chronological relationships between different

extent, and chemical makeup can provide objects or layers. additional information, but they are not as

reliable for determining relative age as the

position of the layers.

 

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