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

magma has been erupted or intruded.

 

546. A black, fine-grained tabular intrusion c) Occur only along continental margins. between two layers of horizontal d) May have profound impacts on the sedimentary rock must logically be a: environment, including land, ocean, and a) Basaltic sill. atmospheric processes. b) -------------------------------------------------------------- that may have been caused by super-plume activity. b) Represent special events in Earth’s history

c) Granitic sill. May affect evolution of life and possibly e) Basaltic dike. cause extinction of some life forms. d) Granitic dike.

 

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Feedback: Large igneous provinces (LIPs) are e) All the possible answers are correct. indeed places where huge amounts of mafic

magma have been erupted or intruded, and Feedback: Pillow basalts are formed when they can have significant impacts on the basaltic lava erupts underwater, such as in the

environment and evolution of life. They are ocean. The rapid cooling of the lava due to

associated with special events in Earth's history contact with water causes it to form rounded

that may be linked to super-plume activity. shapes resembling pillows. This is a

However, LIPs can occur both on continental characteristic feature of underwater volcanic

margins and within continental interiors. They activity. are not restricted to occurring only along

continental margins.

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

550. A light-tan tabular intrusion that cuts

vertically across layered country rock is

most logically a

a) Basaltic sill.

b) Granitic sill.

c) Basaltic dike.

d) Granitic dike.

e) -------------------------------------------------------------- Batholith.

553. Which of the following are NOT related

Feedback to intrusive igneous activity? : Only granitic dike fits the description; basalt would be dark-colored, a sill a) Plutons. would fit between the layers, and a batholith is b) Batholiths. a massive, not tabular, intrusion. c) Diapirs.

d) Xenoliths. e) Scoria.

Feedback: Scoria is actually a type of volcanic rock that is extrusive in nature, formed from

rapidly cooling lava with trapped gas bubbles.

 

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

551. Identify the FALSE statement: Felsic

magma:

a) Is the coolest of magmas.

b) Has about 70% silica and little magnesium

c) -------------------------------------------------------------- and iron.

Is associated with explosive volcanic

 

e) Can form chains of volcanic islands, such as Is likely to form light-tan, pink, or maroon- the Hawaiian Islands. colored rocks. b) Can produce continental hot-spot tracks, such as Yellowstone and the chain of dead d) activity: Is less viscous than mafic magma. a) eruptions. 554. Identify the FALSE statement: Hot-spot

mafic magma. This is because felsic magma volcanoes along the Snake River Plain in Idaho. Feedback: Felsic magma is more viscous than

has a higher silica content. Silica is a very sticky

substance, and it makes it difficult for the c) Has produced Iceland, a volcanic island that

magma to flow. straddles the divergent boundary of the

northern Mid-Atlantic Ridge.

d) Occurs directly above the hot-spot plume

that causes it, and therefore shifts its

location as the plume itself moves slowly

through the mantle.

e) Has been noted at 50 to 100 locations

-------------------------------------------------------------- worldwide, many of which are independent

552. Pillow basalts: of plate-boundary interactions. a) Occur in tabular intrusions called dikes.

b) Are composed of felsic lava. Feedback: Hot-spot activity is associated with c) Are formed in a submarine environment. volcanic activity that occurs above localized

d) Contain large bulbous crystals called areas of high heat flow within the mantle, called

pillows. hot spots. These hot spots do not necessarily

 

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shift their locations as the plume itself moves a) May experience decompression melting as through the mantle. Instead, the overlying it rises to shallow depths. tectonic plate moves over the fixed hot spot, b) May melt if volatiles such as water and leading to the creation of volcanic features such carbon dioxide are added. as chains of volcanic islands (like the Hawaiian c) May melt if heat is transferred to it from hot Islands) or continental hot-spot tracks (like mantle rock rising up into the crust. Yellowstone and the Snake River Plain). The d) Maintains uniform composition as it melts hot spot remains relatively stationary in the and becomes magma. mantle beneath the moving tectonic plate. e) May be even hotter than surface lava

because of the pressure of overlying rock.

Feedback: As rock melts and forms magma, it undergoes partial melting, and the composition

of the resulting magma can change. Magma

can become enriched in certain elements and

minerals due to the preferential melting of

certain minerals at different temperatures. This

process can lead to the formation of magma

-------------------------------------------------------------- with a different composition from the original

555. Magma may cool and freeze to become rock.

solid igneous rock: --------------------------------------------------------------

a) When its dissolved volatiles bubble out. 558. Which of the following is NOT an b) Faster in the presence of circulating intrusive igneous structure?

groundwater. a) Batholith.

c) Within weeks to months, if it intrudes at b) Laccolith.

shallow depth. c) Pillow lava.

d) Very slowly (centuries to a million years) d) Sill.

when it forms a deep pluton. e) Dike.

e) All the possible answers are correct.

Feedback: Pillow lava forms by extrusive flows

Feedback: Magma can cool and freeze to at mid-ocean ridges, where seawater rapidly

become solid igneous rock under a variety of cools basaltic lava into pillow-shaped blobs.

conditions. The rate of cooling and freezing is

affected by the presence of dissolved volatiles,

circulating groundwater, and the depth of

intrusion. The composition of the magma also

plays a role, with mafic magma cooling and

freezing more quickly than silicic magma.

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

556. Factors that influence the chemical

composition of magmas may include:

a) The chemical composition of the source

rock.

b) Only partial melting of the source rock. --------------------------------------------------------------

c) Melting and assimilation of some of the rock 559. Magmas have a variety of chemical

of the magma chamber walls. compositions because:

d) Mixing of magmas brought together from a) They come from a variety of source rocks.

different locations. b) The rocks that melt to make magma are

e) All the possible answers are correct. composed of many minerals, not all of which

melt under the same conditions.

Feedback: The chemical composition of c) The magma’s heat can melt rock from the magmas is influenced by a variety of factors, walls of the magma chamber (assimilation).

including the chemical composition of the d) Different magmas formed in different source rock, partial melting of the source rock, locations can meet and mix. melting and assimilation of some of the rock of e) All the possible answers are correct. the magma chamber walls, and mixing of

magmas brought together from different Feedback: Magmas have a variety of chemical locations. The chemical composition of magma compositions because they come from a variety

determines the type of igneous rock that will of source rocks, which are composed of

form when the magma cools and freezes. minerals with different melting points. The

-------------------------------------------------------------- magma's heat can melt rock from the walls of

557. Identify the FALSE statement: Hot the magma chamber, and different magmas

solid rock in the Earth: formed in different locations can meet and mix.

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

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560. Identify the FALSE statement: molten magma can then erupt at the surface to

Pegmatites: form a hotspot volcano.

a) Are an igneous rock type, distinguished by

their unusual grain size.

b) Can contain crystals up to tens of

centimeters across.

c) Occur in tabular intrusions called pegmatite

dikes.

d) Have intruded at great depth and cooled

very slowly.

e) Often yield precious gemstones.

Feedback: Pegmatites are igneous rocks that

 

form at relatively shallow depths, typically within -------------------------------------------------------------- 10 kilometers of the surface. They crystallize 563. Volatile-rich magma develops gas from a highly volatile magma that is enriched in bubbles as it rises, and this creates even incompatible elements, such as lithium, more buoyant force to move the magma beryllium, and rare earth elements. Pegmatites upward more aggressively. often form in tabular intrusions called pegmatite a) True dikes. b) False

Feedback: Volatile-rich magma rises more quickly and forcefully because the volatiles

expand and form gas bubbles as the magma

rises. The gas bubbles make the magma less

dense and more buoyant, and they create a

pressure gradient that drives the magma

upward.

 

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

561. Wet igneous rock (rock that contains

volatiles) melts at a lower temperature than

does the dry version of that same rock.

a) True

b) False

Feedback: The presence of water (volatiles) in an igneous rock can significantly lower its --------------------------------------------------------------

melting temperature. Water acts as a flux, 564. Igneous rocks formed of igneous debris facilitating the melting of minerals within the blown out of a volcano are called

rock by reducing the viscosity and promoting pegmatites. partial melting. This phenomenon is particularly a) True important in the Earth's mantle, where the b) False addition of water to mantle rocks can lead to the

formation of magma at lower temperatures than Feedback: Igneous rocks formed of igneous in dry conditions. The concept of wet melting debris blown out of a volcano are typically

has implications for understanding the called "pyroclastic rocks" or "pyroclastics," not

dynamics of magmatic processes beneath the pegmatites. Pegmatites are coarse-grained

Earth's surface. igneous rocks with exceptionally large crystals,

 

562. According to the plume hypothesis, the --------------------------------------------------------------plume of a hot spot consists of molten -------------------------------------------------------------- often found in dikes or veins.

565. Vesicles are pieces of wall rock broken

magma rising slowly from the core-mantle off by intruding magma.

 

a) True b) False False boundary and spilling out on Earth’s surface. a) True b)

Feedback: Vesicles are cavities in igneous

Feedback: The plume of a hotspot is thought to rocks that are formed by gas bubbles that were

be made of hot, buoyant solid rock that rises trapped in the magma when it cooled and

slowly from deep within the mantle. As it rises, solidified. They are not pieces of wall rock

it partially melts due to decompression, and the broken off by intruding magma. Vesicles are

common in extrusive igneous rocks, such as

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basalt and scoria. This is because extrusive fractional crystallization, a process by which the

igneous rocks cool and solidify quickly, which chemical composition of a magma changes as

traps the gas bubbles before they have a it cools and minerals crystallize out. Stoping is

chance to escape. Vesicles can also be found not an example of fractional crystallization. in intrusive igneous rocks, but they are less --------------------------------------------------------------

common. This is because intrusive igneous 568. Tuff and breccia are both fragmental rocks cool and solidify slowly, which gives the igneous rocks. gas bubbles more time to escape. Vesicles can a) True range in size from a few millimeters to several b) False centimeters. They can be spherical, elongated,

or irregular in shape. Vesicles that are filled with Feedback: Tuff and breccia are both secondary minerals are called amygdules. fragmental igneous rocks, which means that

they are composed of fragments of other

igneous rocks. Tuff is made up of fine-grained

fragments, while breccia is made up of coarse-

grained fragments. Tuff and breccia are formed

by explosive volcanic eruptions. During an

eruption, the magma is ejected into the air and

breaks up into fragments. The fragments can

be deposited near the volcano, forming a

pyroclastic cone, or they can be carried away

by the wind and deposited over a wider area.

Tuff and breccia are common rocks in volcanic

areas. They are also used as building materials,

-------------------------------------------------------------- especially in areas where volcanic rocks are

566. The deeper an igneous intrusion, the abundant.

slower it cools.

a) True

b) False

Feedback: This is because the surrounding rock acts as insulation, preventing the intrusion

from losing heat quickly. Slower cooling often

results in the formation of larger mineral --------------------------------------------------------------

crystals within the intrusion. 569. "Dry" magmas contain no volatiles;

"wet" magmas contain up to 50% of the

volatile water.

a) True b) False

Feedback: "Dry" magmas contain few or no volatiles, while "wet" magmas can contain

significant amounts of volatiles, including water,

carbon dioxide, sulfur dioxide, and others.

However, the statement incorrectly states that

"wet" magmas contain up to 50% water. While

-------------------------------------------------------------- water can be a significant volatile in magmas,

567. The sequence of mineral production the actual percentage can vary widely

that takes place in a cooling magma, called depending on the specific magma composition

Bowen’s reaction series, is an example of and conditions. the process called stoping. --------------------------------------------------------------

a) True 570. The particles ejected by volcanoes b) False during explosive eruptions are collectively

called:

Feedback: Bowen's reaction series is a a) Biochemical constituents. sequence of minerals that crystallize out of b) Volcanic compounds. magma as it cools. The sequence is based on c) Carbonate minerals. the melting points of the minerals, with the d) Pyroclastic materials. highest-melting-point minerals crystallizing first e) Intrusive metamorphics. and the lowest-melting-point minerals

crystallizing last. Stoping is a process by which Feedback: Particles ejected by volcanoes magma ascends through the crust by breaking during explosive eruptions are collectively

off and assimilating pieces of the surrounding called pyroclastic materials. These materials

rock. Bowen's reaction series is an example of include a range of fragments, such as ash,

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lapilli (small rocks), and larger blocks and surface, the water vaporizes and is released

bombs. The term "pyroclastic" is derived from into the atmosphere. While water vapor is the

the Greek words "pyro," meaning fire, and most abundant gas, volcanic eruptions also

"clast," meaning fragment, emphasizing their release other gases like carbon dioxide, sulfur

association with volcanic activity and explosive dioxide, and smaller amounts of other

processes. compounds depending on the composition of

the magma.

 

a) 573. Which of the following is an example of They heat the atmosphere. a shield volcano? b) Volcanic dust and gas can reduce the a) Mount St. Helens, Washington State. amount of solar radiation that penetrates the b) Mount Merapi, Indonesia. atmosphere. c) 571. Volcanic eruptions can affect the -------------------------------------------------------------- climate because: --------------------------------------------------------------

c) They change the elevation of the land. Mauna Loa, Hawaii. d) Cerro Negro, Nicaragua. d) All of the preceding.

 

Feedback Feedback: A shield volcano is a type of volcano : The gases and dust particles characterized by its broad, gently sloping profile thrown into the atmosphere during volcanic resembling a warrior's shield. These volcanoes eruptions have influences on climate. Most of are typically formed by the accumulation of low- the particles spewed from volcanoes cool the viscosity basaltic lava flows over a large area. planet by shading incoming solar radiation. The

cooling effect can last for months to years

depending on the characteristics of the

eruption. Volcanoes have also caused global

warming over millions of years during times in

Earth’s history when extreme amounts of

volcanism occurred, releasing greenhouse

gases into the atmosphere.

 

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

574. Whether volcanic eruptions are very

explosive or relatively quiet is largely

determined by:

a) The amount of gas in the lava or magma. b) The ease or difficulty with which the gas

escapes to the atmosphere.

-------------------------------------------------------------- c) The viscosity of a lava. 572. The gas most commonly released d) All of the preceding.

during a volcanic eruption is:

a) Feedback: The explosiveness of a volcanic Water vapor.

b) eruption is determined by three main factors: Carbon dioxide.

c) the amount of gas in the lava or magma, the Sulfur dioxide.

d) ease or difficulty with which the gas escapes to Hydrogen sulfide.

e) the atmosphere, and the viscosity of the lava or Oxygen.

magma. Magmas with high gas content and

Feedback high viscosity are more likely to produce : The most commonly released gas

during a volcanic eruption is water vapor. As explosive eruptions, while magmas with low

magma rises to the surface, it carries with it gas content and low viscosity are more likely to

water and other volatile substances. When the produce non-explosive eruptions. magma reaches lower pressures near the --------------------------------------------------------------

 

112

575. _____ is a rock composed of frothy Feedback: Aʻā is not a type of pyroclastic

volcanic glass. material. Aʻā refers to a type of lava flow

a) Obsidian characterized by its rough, blocky texture and

b) Basalt slow-moving, viscous nature. It's formed from

c) Tuff highly viscous lava that breaks into angular,

d) Pumice sharp fragments as it cools and solidifies. The

e) Volcanic breccia other options: ash, dust, lapilli, and bombs, are

all forms of pyroclastic material, which includes

Feedback: Pumice is a type of rock composed various particles ejected during volcanic

of frothy volcanic glass. It forms when highly eruptions. gas-rich lava is ejected during a volcanic

eruption and cools rapidly, trapping gas

bubbles within the glassy structure. This results

in a lightweight and porous rock with a

characteristic appearance full of interconnected

cavities or vesicles. Pumice is commonly used

as an abrasive material, in horticulture, and

even as a personal care product due to its

ability to exfoliate the skin. --------------------------------------------------------------

578. Which of these is NOT a major type of

volcano?

a) Shield. b) Cinder cone. c) Composite. d) Stratovolcano. e) Spatter cone.

 

-------------------------------------------------------------- major type of volcano. They are relatively small and are often found on the flanks of larger Feedback: Spatter cones are not considered a

576. A lava flow with a smooth, undulating,

 

a) blobs of lava are ejected from a vent and Pahoehoe. accumulate around the vent, creating a cone- and ropy surface is called: volcanoes. Spatter cones are formed when

c) shaped structure. While they are not as Pillow lava significant or widely recognized as shield, b) Aʻā.

e) cinder cone, and composite volcanoes Lava tube. (stratovolcanoes), they are still interesting d) Lahar.

 

Feedback volcanic features formed by the accumulation of : Pahoehoe is a Hawaiian word that ejected lava fragments. means "flat, swirly-swirly." Pahoehoe lava flows are characterized by their smooth, undulating, and ropy surfaces. They are formed from low-

viscosity lava that flows relatively slowly. The

ropy surface texture is caused by the

movement of the lava beneath a thin, solid

crust.

 

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

579. An example of a composite volcano is:

a) Mount Rainier. b) Fujiyama. c) Mount Vesuvius. d) All of the preceding.

 

577. Which of these is NOT a type of Feedback: Composite volcanoes, also known pyroclastic material? -------------------------------------------------------------- a) Ash. steep slopes and a combination of explosive as stratovolcanoes, are characterized by their

 

c) Lapilli. conical shape and are built up by the Aʻā. b) Dust. and effusive eruptions. They typically have a

d) accumulation of lava flows, volcanic ash, and

e) Bomb. other volcanic debris. Mount Rainier, Fujiyama

 

113

(Mount Fuji), and Mount Vesuvius are all earthquake activity around a volcano, and

examples of composite volcanoes. alerting nearby residents of an imminent

eruption are important components of volcanic

hazard mitigation. These strategies aim to

reduce the impact of volcanic hazards by

understanding the risks, predicting eruptions as

much as possible, and informing and

evacuating communities in the volcano's

vicinity.

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

582. Temperatures at which lavas solidify

 

580. Which volcano is ____°C for mafic rocks. NOT usually made of a) -------------------------------------------------------------- range from about ____°C for silicic rocks to

 

: The temperatures at which lavas

 

Feedback: Composite cones, also known as solidify vary based on the composition of the rocks. Silicic (felsic) rocks, which have higher stratovolcanoes, are not usually made of basalt. silica content and are more viscous, solidify at Unlike shield volcanoes, which are primarily temperatures around 700°C. On the other composed of basaltic lava flows, composite hand, mafic rocks, which are lower in silica and cones are characterized by alternating layers of more fluid, solidify at higher temperatures of lava flows and pyroclastic materials, such as about 1,200°C. These temperature ranges ash and volcanic rocks. These layers can reflect the differences in chemical composition include a variety of lava compositions, including and viscosity between the two types of lava. andesite and dacite, which have higher silica -------------------------------------------------------------- content compared to basalt. Composite cones 583. One gas typically NOT released during are typically more explosive in nature due to the a volcanic eruption is: b) Composite cone. 700, 1,200 d) 1,000, 2,000 c) Spatter cone. d) Cinder cone. Feedback a) basalt? b) 300, 1,000 Shield. c) 100, 200

 

higher viscosity of their lava, leading to the a) Water vapor. accumulation of pyroclastic materials and b) Carbon dioxide. forming the recognizable stratified shape. c) Sulfur dioxide. d) Hydrogen sulfide. e) Oxygen.

Feedback: Water vapor, carbon dioxide, sulfur dioxide, and hydrogen sulfide are all common

gases that are released during volcanic

eruptions. Oxygen is not typically released

during volcanic eruptions because it is not a

major constituent of magma.

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

584. Mafic rocks contain about ____% silica.

a) 10 b) 25

-------------------------------------------------------------- c) 50 581. Which of the following is NOT a d) 65

component of volcanic hazard mitigation? e) 80

a) Mapping older volcanic deposits.

b) Preventing a volcanic eruption. Feedback: Mafic rocks contain about 45 to c) Monitoring earthquake activity around a 55% silica. Mafic rocks are igneous rocks that

volcano. are rich in dark-colored minerals, such as

d) Alerting nearby residents of an imminent olivine, pyroxene, and amphibole. They are

eruption. typically formed from the cooling of magma that

is rich in magnesium and iron. Mafic rocks are

Feedback: Preventing a volcanic eruption is less common than felsic rocks, but they make

not a component of volcanic hazard mitigation up the majority of the Earth's crust. because volcanic eruptions are natural --------------------------------------------------------------

geological processes driven by various factors 585. Silicic (Felsic) rocks contain about within the Earth's crust. While it's not possible ____% silica. to prevent an eruption, the other options a) 10 mapping older volcanic deposits, monitoring b) 25

114

c) 50 e) Fissure eruptions/cinder cones. d) 70

e) 80 Feedback: Water-saturated flows of volcanic

debris, called "lahars," are common on

Feedback: Silicic (felsic) rocks contain about "composite" volcanoes. Lahars are mixtures of

65 to 75% silica. Silicic rocks are igneous rocks volcanic ash, debris, and water that can flow

that are rich in light-colored minerals, such as rapidly down the slopes of a volcano during or

quartz, feldspar, and mica. They are typically after an eruption. Composite volcanoes, also

formed from the cooling of magma that is rich in known as stratovolcanoes, are characterized

silicon and aluminum. Silicic rocks are more by their steep sides and alternating layers of

common than mafic rocks, but they make up a lava and pyroclastic materials. The presence of

smaller percentage of the Earth's crust. snow and ice on the summit of composite

-------------------------------------------------------------- volcanoes can contribute to the formation of

586. Which is NOT an extrusive igneous lahars when volcanic activity melts the frozen

rock? material.

a) Granite.

b) Rhyolite.

c) Basalt.

d) Andesite.

Feedback: Granite is a light-colored igneous rock with grains large enough to be visible with

the unaided eye. It forms from the slow

crystallization of magma below Earth's

surface. Granite is composed mainly of quartz

and feldspar with minor amounts of mica,

amphiboles, and other minerals.

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

587. An igneous rock made of pyroclasts --------------------------------------------------------------

has a texture called: 589. A lava flow made up of angular blocks

a) Fragmental. and fragments is a/an _____ flow. b) Vesicular. a) Lava tube. c) Porphyritic. b) Aʻā. d) Fine-grained. c) Pahoehoe.

d) Lahar.

Feedback: An igneous rock made of e) Caldera. pyroclasts, which are fragments ejected during

volcanic eruptions, has a texture called Feedback: A'ā lava flows are characterized by "fragmental." This texture is characterized by their rough, jagged, and clinkery surfaces. They

the presence of various-sized fragments, often are formed from high-viscosity lava that flows

angular or rounded, that are cemented relatively quickly. The rough surface texture is

together. These fragments can range in size caused by the rapid cooling of the lava, which

from tiny ash particles to larger volcanic rocks forms a brittle crust that breaks into angular

and may include materials like pumice, ash, blocks and fragments. and volcanic breccia. The term "fragmental"

reflects the diverse nature of the particles

making up the rock.

 

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

-------------------------------------------------------------- 590. An incandescent cloud of gas and 588. Water-saturated flows of volcanic particles erupted from a volcano is a:

debris called _____ are common on _____ a) Spatter cone. volcanoes. b) Lapilli.

a) Nuee ardentes/shield. c) Nuee ardente. b) Lava flows/lava dome. d) Caldera. c) Lahars/composite. e) Volcanic tremor. d) Pillow lava/submarine.

115

Feedback: An incandescent cloud of gas and Volcanic tremors are often associated with the

particles erupted from a volcano is known as a movement of magma towards the surface, and

"Nuee ardente," which is also commonly they can be an important indicator of potential

referred to as a pyroclastic flow. Nuee ardente volcanic activity. Monitoring volcanic tremors

is a French term that translates to "glowing can help scientists assess the state of a

cloud." These highly destructive flows consist of volcano and its potential for eruption. hot gases, ash, and volcanic debris that move --------------------------------------------------------------

rapidly down the flanks of a volcano during an 593. Which one of the following is one of explosive eruption. They can reach extremely Earth’s main volcanic belts? high temperatures and speeds, posing a) Appalachian belt. significant hazards to anything in their path. b) East African belt.

c) Indian Ridge belt. d) East Pacific belt. e) Mediterranean belt.

Feedback: Mediterranean belt is one of Earth's main volcanic belts. The Mediterranean region

is home to several active and historically active

volcanoes, and it's known for its geological

activity, making it a significant volcanic belt.

 

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

591. Pillow lava forms when:

a) Thick layers of pyroclastic layers

accumulate.

b) Lava erupts under water.

c) Globs of lava stick together on a lava flow’s

surface.

d) Pressure within a flow causes its surface to

buckle. --------------------------------------------------------------

e) A volcano’s summit collapses. 594. A small, steep-sided volcano made up

Feedback: Pillow lava forms when lava erupts a) of pyroclastic materials is a: Cinder cone.

underwater. The cold water rapidly cools the b) Lava dome. outer surface of the lava, forming a thin, solid c) Shield volcano. crust. The molten lava inside the crust d) Caldera. continues to flow, pushing out the crust and e) Nuee ardente. forming a pillow-like shape.

Feedback: A cinder cone is a steep conical hill of loose pyroclastic fragments, such as either

volcanic clinkers, volcanic ash, or cinder that

has been built around a volcanic vent. The

pyroclastic fragments are formed by explosive

eruptions or lava fountains from a single,

typically cylindrical, vent.

 

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

592. The shaking that takes place when

magma moves beneath the surface is called

a) Volcanic tremor.

 

e) Basalt plateau. 595. The Hawaiian volcanoes are made up Volcanic explosivity index. mostly of lava that cools to form: a) Rhyolite. Feedback : The shaking that takes place when b) Granite. magma moves beneath the surface is called c) c) Pyroclastic intrusion. -------------------------------------------------------------- d) b) Columnar joints.

"volcanic tremor." This is a type of seismic Basalt. d) Welded tuff. activity caused by the movement of magma, e) Andesite. gas, and other fluids within the Earth's crust.

 

116

Feedback: The Hawaiian volcanoes, such as more explosive volcanic eruptions due to their

Mauna Loa and Mauna Kea, are made up higher viscosity. mostly of basaltic lava. Basalt is a type of mafic --------------------------------------------------------------

lava with low viscosity, allowing it to flow 599. Rhyolitic (felsic) magma is typically less relatively easily and cover large areas before fluid than basaltic (mafic) magma. solidifying. The Hawaiian Islands are located on a) True a hot spot in the Earth's mantle, where the b) False upwelling of magma produces basaltic lava

flows, contributing to the growth of these shield Feedback: Rhyolitic magma has a higher silica volcanoes. content, which increases its viscosity. Higher

-------------------------------------------------------------- viscosity means the magma is thicker and less

596. A magma's viscosity is affected by its able to flow easily compared to the more fluid

composition, temperature, and amount of basaltic magma. dissolved gases.

a) True

b) False

Feedback: The viscosity of magma is indeed influenced by its composition, temperature, and

the amount of dissolved gases.

Composition: The more silica (SiO2) a magma contains, the more viscous it will be. Silica is a

very viscous material, so it slows down the flow

of magma. --------------------------------------------------------------

Temperature: The higher the temperature of a 600. What is the major dissolved volatile magma, the less viscous it will be. This is constituent in both magmas and volcanic

because heat causes the atoms in the magma gases? to move faster, which makes the magma less a) Water. resistant to flow. b) Carbon dioxide. Dissolved gases: The more dissolved gases a c) Hydrogen chloride. magma contains, the less viscous it will be. This d) Methane. is because gas bubbles make the magma less e) Sulfur. dense, which makes it easier to flow.

-------------------------------------------------------------- Feedback: Water is the major dissolved volatile 597. In general, the less silica in a magma, constituent in both magmas and volcanic

the greater its viscosity. gases. It is present in all magmas, but it is

a) True especially abundant in volatile-rich magmas. As

b) False magma rises to the surface, the pressure on it

decreases and the water expands, forming gas

Feedback: In general, the more silica in a bubbles. These gas bubbles make the magma

magma, the greater its viscosity. Silica-rich less dense and more buoyant, which helps it to

magmas tend to be more viscous because rise more quickly. Carbon dioxide, hydrogen

silica tetrahedra can form strong bonds, chloride, methane, and sulfur are also present

hindering flow and making the magma thicker in magmas and volcanic gases, but they are not

and more resistant to flow. Magma with lower as abundant as water. Carbon dioxide is

silica content tends to be less viscous and more released from magma when it degasses as it

fluid. rises to the surface. Hydrogen chloride,

-------------------------------------------------------------- methane, and sulfur are released from magma

598. A magma's viscosity is directly related when it reacts with other minerals in the

to its __________ content. surrounding rock.

a) Iron. --------------------------------------------------------------

b) Oxygen. 601. The viscosity of the magma, plus the c) Aluminum. quantity of dissolved gases and the ease

d) Potassium. with which they can escape, determines

e) Silica. how violent a volcanic eruption will be.

a) True

Feedback: A magma's viscosity is directly b) False related to its silica content. Silica (silicon

dioxide) is a major component of magma and Feedback: The viscosity of the magma, the plays a crucial role in determining the magma's quantity of dissolved gases, and the ease with

viscosity. Higher silica content results in more which they can escape all play a role in

viscous magma, making it thicker and less determining how violent a volcanic eruption will

prone to flow easily. Silica-rich magmas, such be. More viscous magmas with a higher gas

as those containing quartz, tend to produce

117

content and less ease for the gases to escape a steep slope. Cinder cones are formed from

are more likely to produce explosive eruptions. the accumulation of tephra, which is loose,

Less viscous magmas with a lower gas content cindery material that is ejected from a volcano

and more ease for the gases to escape are during an eruption. The other two major volcano

more likely to produce non-explosive eruptions. types are shield volcanoes and composite

-------------------------------------------------------------- volcanoes. Shield volcanoes are the largest

602. Magmas that produce felsic rocks type of volcano and can be several miles tall.

(granite and its extrusive equivalent, Composite volcanoes are also tall, but they are

rhyolite) typically contain less than 50 steeper than shield volcanoes. percent silica.

a) True

b) False

Feedback: Magmas that produce felsic rocks (such as granite and rhyolite) typically contain

more than 50 percent silica. Felsic rocks are

characterized by their high silica content, which

contributes to their light color and higher

viscosity. These rocks are formed from

magmas that have a relatively high proportion

of silica-rich minerals, such as quartz and

feldspar.

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

605. The structures that result from the

emplacement of igneous material at depth

are called lahars.

a) True b) False

Feedback: The structures that result from the emplacement of igneous material at depth are

typically referred to as "intrusions." Intrusions

include various features formed when magma

solidifies below the Earth's surface, such as

dikes, sills, and plutons. These structures play

a crucial role in shaping the Earth's crust and

can have significant geological and economic

implications.

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

603. Shield cones are typically large, built

primarily of basaltic lava flows, and contain

a small percentage of pyroclastic material.

a) True

b) False

Feedback: Shield cones are typically large, built primarily of basaltic lava flows, and contain

a small percentage of pyroclastic material.

Shield cones are low, broad, and gently sloping --------------------------------------------------------------

volcanoes that form from very fluid lava that 606. Shield volcanoes are the most common spreads over a large area. They may have product of __________ volcanism. some cinder cones or spatter cones on their a) Lahar. flanks, which produce pyroclastic material such b) Explosive. as ash and cinders. c) Hotspot. -------------------------------------------------------------- d) Rift. 604. The smallest of the three volcano types e) Random.

are the cinder cones.

a) True Feedback: Shield volcanoes are the most b) False common product of hotspot volcanism. Hotspot

volcanism is caused by plumes of hot magma

Feedback: Cinder cones are the smallest of the that rise from deep within the Earth. These

three major volcano types. They are typically plumes can be stationary or moving, and they

less than 1,000 feet (300 meters) tall and have

118

often produce chains of volcanoes as they fractures. They are typically thin and vertical,

move across the Earth's surface. and they can cross-cut existing rock layers.

Dikes are formed when magma rises to the

surface and encounters a fracture in the rock.

The magma forces its way into the fracture, and

as it cools and solidifies, it forms a dike. Dikes

can be found all over the world, and they are

often associated with volcanic activity.

However, dikes can also form in areas that are

not volcanically active.

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

607. Most volcanoes are fed magma

through short conduits or pipes.

a) True

b) False

Feedback: Most volcanoes are fed magma through short conduits or pipes. These conduits

are typically only a few kilometers long and

connect the magma chamber to the volcano's

surface. Magma rises through the conduits --------------------------------------------------------------

because it is less dense than the surrounding 610. Which volcano type is a very large, rock. The magma pushes its way up through gently sloping mound composed mainly of

the conduits and eventually erupts at the basaltic lava flows? surface. Some volcanoes, however, are fed a) Caldera. magma through longer conduits or pipes. b) Cinder cone. These conduits can be tens of kilometers long c) Stratovolcano. and connect the magma chamber to the d) Composite. volcano's surface in a different location. e) Shield.

Feedback: Shield volcanoes are the largest type of volcano and are composed mainly of

basaltic lava flows. They have a very gentle

slope and can be several miles tall. The largest

shield volcano on Earth is Mauna Loa in Hawaii,

which rises over 33,500 feet (10,200 meters)

above the ocean floor.

 

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

608. Most intraplate volcanism occurs

where a mass of hotter than normal mantle

material ascends toward the surface.

a) True

b) False --------------------------------------------------------------

611. A large depression at the summit of a

Feedback: This is called a mantle plume or a volcano is called a __________. hotspot. A mantle plume is a column of hot rock a) Lahar. that rises from the core-mantle boundary and b) Caldera. melts as it reaches shallower depths. A hotspot c) Neck. is a volcanic region that is fed by a mantle d) Fissure. plume and produces volcanoes that are not e) Batholith. related to plate boundaries.

-------------------------------------------------------------- Feedback: A caldera is a large, bowl-shaped 609. Dikes are tabular discordant bodies depression that forms at the summit of a

that are produced when magma is injected volcano when the magma chamber beneath the

into fractures. volcano collapses. Calderas can be several

a) True kilometers wide and deep, and they are often

b) False filled with water, forming crater lakes. Calderas

are formed when a volcano erupts and expels a

Feedback: Dikes are tabular discordant bodies large volume of magma. The emptying of the

that are produced when magma is injected into

 

119

magma chamber causes the ground above the features on the Moon's surface, covering about

chamber to collapse, forming a caldera. 16% of the total area. The lava that filled the

maria is mafic in composition and relatively

fluid, which allowed it to flow long distances and

fill the large impact basins. The lunar maria are

important geological features because they

provide information about the early history of

the Moon and contain valuable resources.

 

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

612. Many subduction-zone volcanoes are

located in a region on Earth called the "Ring

of Fire." --------------------------------------------------------------

a) True 614. Rhyolite lava: b) False a) Has more silica than basalt lava does.

b) Indicates the tendency for explosive activity.

Feedback: The Ring of Fire is a horseshoe- c) May freeze in the vent and emerge as a shaped region around the Pacific Ocean that is spine. home to many of the world's most active d) May form a lava dome above the vent. volcanoes and earthquake zones. It is caused e) All the possible answers are correct. by the subduction of tectonic plates beneath the

Pacific Plate. As the plates subduct, they melt Feedback: Rhyolite lava has more silica than and release water vapor and other gases. This basalt lava. It is also more viscous and less fluid

mixture rises through the overlying mantle and than basalt lava. This makes it more likely to

crust, eventually erupting as magma. The Ring form explosive eruptions, lava domes, and

of Fire is responsible for about 90% of the spines. Rhyolite lava flows are typically thick

world's earthquakes and 75% of its volcanic and blocky, and they may contain gas bubbles

eruptions. It includes countries such as Japan, and vesicles. Rhyolite lava domes are formed

Indonesia, the Philippines, Chile, and the when rhyolite lava is too viscous to flow very far

United States. and instead builds up around the vent. Rhyolite

spines are formed when rhyolite lava freezes in

the vent and then emerges as a sharp, needle-

like structure.

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

615. The largest intrusive igneous bodies

are batholiths.

a) True b) False

 

613. Most mare volcanism on the Moon has can cover extensive areas and can have occurred in the bottoms of very large, very dimensions measured in tens to hundreds of old __________. kilometers. They are typically composed of a a) Impact craters. variety of plutonic rock types and are formed b) -------------------------------------------------------------- irregularly shaped intrusion of igneous rock that forms beneath the Earth's surface. Batholiths Feedback: A batholith is a massive and often

c) from the solidification of magma that has been Rifts.

d) emplaced at depth over long periods of time. Calderas.

Island arcs.

e) Subduction zones.

Feedback: Most mare volcanism on the Moon occurred in the bottoms of large, old impact

craters. These craters were created by ancient

asteroid impacts and later filled with lava from

eruptions from the lunar mantle. The lunar

maria are large, dark, basaltic plains on the

Moon. They are the largest topographic --------------------------------------------------------------

 

120

616. The greatest volume of volcanic rock is b) False

produced along the oceanic ridge system.

a) True Feedback: Composite volcanoes are usually b) False found at destructive plate

margins. A destructive plate boundary happens

Feedback: The oceanic ridge system is where where an oceanic and continental plate move the most volcanic rock is produced. The ridge towards each other. The heavier, more dense system is formed by the spreading of the oceanic plate is forced under the continental Earth's tectonic plates. As the plates spread, plate. new mantle material rises to the surface and

melts. This molten material, called magma,

then erupts to form new oceanic crust. The

oceanic ridge system is responsible for

producing about 70% of the Earth's volcanic

rock. The other 30% of volcanic rock is

produced by volcanoes that are located on

land.

 

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

619. Andesitic or rhyolitic magma is

-------------------------------------------------------------- characteristically extruded from volcanoes 617. Mantle plumes and hot spots are often within a continental margin volcanic arc.

associated with intraplate volcanism. a) True

a) True b) False b) False

Feedback: This is because the melting of the

Feedback: Intraplate volcanism refers to subducting oceanic crust and the overlying volcanic activity that occurs within a tectonic mantle wedge produces these types of

plate, away from plate boundaries. Mantle magmas. Continental margin volcanic arcs are plumes are upwellings of abnormally hot rock in formed when oceanic crust subducts beneath the Earth's mantle that can create a localized continental crust. As the oceanic crust

area of increased heat and volcanic activity. Hot subducts, it heats up and releases water. This spots are surface expressions of mantle water lowers the melting point of the

plumes, where magma from the mantle can surrounding mantle rock, causing it to melt. The erupt through the crust. These intraplate molten material, called magma, then rises to volcanic features can result in the formation of the surface and erupts to form a volcano. volcanic islands or volcanic fields in the middle Andesite and rhyolite are felsic rocks, which of tectonic plates. Well-known examples means that they are high in silica. Silica is a include the Hawaiian Islands, formed by a very sticky substance, and it makes it difficult mantle plume and hot spot activity within the for the magma to flow. As a result, andesitic and Pacific Plate. rhyolitic magmas are often associated with

explosive volcanic eruptions.

 

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

620. The relation between volcanic

-------------------------------------------------------------- eruptions and climate cannot be

618. Most active composite cones are established.

located in the region of the central Pacific a) True Ocean. b) False

a) True

121

Feedback: Volcanic eruptions can have properties such as viscosity, color, and mineral

significant effects on the Earth's climate, content. particularly through the injection of large --------------------------------------------------------------

amounts of volcanic gases and particles into 622. Pillow lavas are evidence of what the atmosphere. When a volcano erupts, it volcanic circumstance? releases gases such as sulfur dioxide (SO2) a) A submarine volcano. and ash particles into the atmosphere. These b) High-silica-content magma. materials can have a cooling effect on the c) An explosive eruption. climate by reflecting sunlight and reducing the d) A phreatomagmatic eruption. amount of solar radiation that reaches the e) Caldera formation. Earth's surface. Sulfur dioxide can also convert

into sulfate aerosols in the upper atmosphere, Feedback: Pillow lavas are typically associated which can persist for several years and with submarine volcanoes or volcanic activity

contribute to a temporary cooling of the planet. that occurs underwater. When basaltic lava

Historical records and scientific studies have erupts underwater, it cools rapidly and forms

shown that major volcanic eruptions can lead to characteristic pillow-shaped structures. The

short-term global cooling events known as rapid cooling prevents the development of the

"volcanic winters." These events can impact typical surface features seen in terrestrial lava

weather patterns, reduce global temperatures, flows. Therefore, the presence of pillow lavas is

and have various ecological and societal evidence of volcanic activity beneath the ocean

implications. For example, the 1815 eruption of or in other underwater environments. Mount Tambora in Indonesia caused the "Year

Without a Summer" in 1816, with abnormally

cold temperatures and crop failures around the

world. Similarly, the 1991 eruption of Mount

Pinatubo in the Philippines led to a temporary

cooling of the Earth's climate.

 

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

623. A single eruption that occurs in a linear

pattern through an extremely elongate vent

is called a:

a) Fault eruption. b) Joint eruption. c) Boundary eruption. d) Fissure eruption. e) Line eruption.

Feedback: Runny magmas (i.e., mafic) will sometimes erupt along recently-opened faults

or fissures. This occurs in extensional areas as

-------------------------------------------------------------- well as where large slumping occurs along the

side of an active volcano.

621. Lava is:

a) Always produced during any volcanic

activity.

b) Molten rock that cools and hardens on

Earth’s surface.

c) All the same chemical composition, whether

it’s rhyolite or basalt.

d) The most life-threatening volcanic product of

any eruption.

e) All the possible answers are correct.

 

Feedback -------------------------------------------------------------- : Lava is molten rock that is expelled 624. A lahar is: from a volcano during an eruption and then a) A glowing cloud of pyroclastic grains and hot cools and solidifies upon exposure to the gas. Earth's surface. It can have different chemical b) A cinder cone. compositions depending on the type of magma c) An enlarged volcanic crater. it originates from, leading to variations in d) A volcanic mud and debris flow that resembles fluid concrete.

 

122

e) A lava lake in a summit crater. d) Lapilli.

e) Pahoehoe.

Feedback: Lahar is an Indonesian term that describes a hot or cold mixture of water and Feedback: Lapilli is not a form of lava; it refers rock fragments that flows down the slopes of a to small volcanic rock fragments ejected during

volcano and typically enters a river valley. volcanic eruptions. These fragments can range

in size from small particles to pebble-sized

pieces and are often produced during explosive

eruptions.

 

-------------------------------------------------------------- -------------------------------------------------------------- 627. Lava of low viscosity: 625. Volcanic mud and debris flows, a) Could logically build a shield cone. composed of ash, debris, and water: b) Indicates an area that has little potential for a) Occur only in Arctic regions because snow explosive eruptions. supplies the water for mud. c) Is logically basalt. b) Leave messes but rarely kill people because d) Has low silica content. they flow slowly. e) All the possible answers are correct. c) Are called nuée ardents. d) Have often resulted in damage and death to Feedback : Lava of low viscosity has a low silica humans and their property. content, which makes it flow more easily. This e) Are extremely rare. type of lava is likely to be basalt and is

 

Feedback associated with less explosive eruptions. It can : Volcanic mud and debris flows, also build shield cones. called lahars. Lahars are mixtures of volcanic ash, debris, and water that can flow down the slopes of a volcano during or after an eruption.

They can be extremely destructive and

dangerous due to their high speed and ability to

carry large boulders and debris. Lahars can

travel long distances and bury communities,

infrastructure, and agricultural areas in their

path. They are a significant volcanic hazard,

and areas around volcanoes prone to lahars

 

require careful monitoring and planning for -------------------------------------------------------------- mitigation. 628. Which of the following events is a warning sign of imminent volcanic eruption?

a) Earthquake activity. b) Change in heat flow from the volcano’s

surface.

c) Bulges on the volcano’s surface. d) Increase in gas emissions and hydrothermal

activities.

e) All the possible answers are correct.

Feedback: All of the following events are warning signs of imminent volcanic eruption:

earthquake activity, change in heat flow from

-------------------------------------------------------------- the volcano's surface, bulges on the volcano's

626. Which of the following is NOT a form of surface, and increase in gas emissions and

lava? hydrothermal activities. It is important to be

a) Aʻā. prepared for the possibility of an eruption if any

b) Andesite. of these warning signs are observed. c) Rhyolite. --------------------------------------------------------------

 

123

629. Which of the following does NOT Feedback: The Ring of Fire is a horseshoe-

describe the architecture (structure) of a shaped area in the Pacific Ocean basin that is

volcano? known for its high concentration of volcanic

a) Vent. activity and frequent earthquakes. It includes

b) Vesicle. the Aleutian Islands in Alaska, the Cascades in

c) Fissure. the northwest United States, Mt. Pinatubo in the

d) Magma chamber. Philippines, and the Andes in South America.

e) Crater. Iceland, while a volcanic region, is located in

the North Atlantic Ocean and is not considered

Feedback: Vesicles are small cavities or gas part of the Pacific Ring of Fire. bubbles that can form within igneous rocks,

including volcanic rocks. They are a result of

gases dissolved in magma during volcanic

activity. The other options, vent, fissure,

magma chamber, and crater, are all features

that are associated with the architecture of a

volcano.

 

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

632. Which of the following volcanic

phenomena can be triggered by a volcanic

eruption under ice?

a) Jokulhaup. b) Hyaloclastite. c) Lava dome and spine. d) Lava tube.

-------------------------------------------------------------- e) Columnar jointing. 630. What is the term for an unconsolidated

accumulation of any size of pyroclastic Feedback: Jokulhaup (also spelled

grains? jökulhlaup) is a term used to describe a glacial

a) outburst flood that can be triggered by a Aerosol.

b) volcanic eruption under ice. When a volcano Accretionary lapilli.

c) erupts beneath a glacier or ice cap, the heat Pelé’s hair and tears.

d) from the eruption can melt large amounts of ice. Tephra.

e) The resulting water can accumulate and create Tuff.

a rapidly flowing flood as it breaks through or

Feedback under the ice. : Tephra is the general term for any unconsolidated accumulation of pyroclastic

grains, regardless of size. Pyroclastic grains

are fragments of rock that are ejected from a

volcano during an eruption. Tephra can range

in size from ash to bombs, and it can be

deposited over a wide area.

 

Hyaloclastite: A type of volcanic rock formed by the interaction between lava and water, often

occurring underwater or beneath glaciers.

-------------------------------------------------------------- Lava dome and spine: Features associated 631. with the extrusion of highly viscous lava on the Which of the following volcanic areas is

NOT surface. part of the Ring of Fire?

a) Iceland. Lava tube: A tunnel-like structure formed by b) Aleutians, Alaska. the flow of lava, typically underground. c) Cascades, northwest United States. Columnar jointing: A pattern of fractures that d) Mt. Pinatubo, Philippines. develop in volcanic rocks as they cool and

e) Andes, South America. contract.

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

124

633. Individual volcanoes erupt fairly viscosity, temperature, and gas content of the

regularly, and if the recurrence interval is magma. Some common types of subaerial

known, their eruptions can be accurately eruptions are: predicted. Plinian: These are explosive eruptions that

a) True produce large columns of ash and gas that can

b) False reach the stratosphere. They also produce

pyroclastic flows, which are fast-moving

Feedback: While some volcanoes may have a mixtures of hot rock and gas that can devastate

history of erupting at fairly regular intervals, large areas. An example of a Plinian eruption is

accurately predicting volcanic eruptions is the 1980 eruption of Mount St. Helens. extremely challenging and often not possible Hawaiian: These are effusive eruptions that with high precision. The behavior of volcanoes produce fluid basaltic lava flows that can travel

is influenced by complex geological, magmatic, long distances. They also produce lava

and tectonic processes that can vary widely fountains, which are jets of lava that can reach

from one eruption to another. Volcanic activity hundreds of meters high. An example of a

is monitored through various methods such as Hawaiian eruption is the ongoing eruption of

seismicity, gas emissions, ground deformation, Kilauea. and changes in volcanic activity patterns. While Strombolian: These are moderate eruptions these monitoring techniques can provide that produce bursts of lava and gas that can

valuable information about a volcano's behavior reach tens to hundreds of meters high. They

and potential for eruption, the exact timing, size, also produce cinder cones, which are small

and style of an eruption remain difficult to volcanic hills made of loose volcanic fragments.

predict. An example of a Strombolian eruption is the

-------------------------------------------------------------- 2002-2003 eruption of Stromboli. 634. The eruption of rhyolitic lava generally --------------------------------------------------------------

creates a steep feature called a lava dome. 636. Lava is the greatest volcanic hazard to

a) True human life because it travels so fast. b) False a) True

b) False

Feedback: Rhyolitic lava is viscous and tends to solidify quickly, leading to the formation of Feedback: Lava is generally not the greatest steep-sided lava domes during eruptions. This volcanic hazard to human life because it

is due to the high silica content in rhyolitic lava, typically moves slowly enough for people to

which makes it less fluid and more prone to evacuate from its path. Other volcanic hazards

building up and forming dome-like structures. like pyroclastic flows, ash fall, and volcanic

gases can pose greater immediate threats to

human life due to their speed and potential for

widespread destruction.

 

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

635. Most subaerial volcanoes on Earth

occur in which setting?

a) Mid-ocean ridges.

b) Convergent boundaries. --------------------------------------------------------------

c) 637. Short-term prediction of earthquakes is Divergent boundaries.

d) usually possible; short-term prediction of Oceanic hot spots.

e) imminent volcanic eruption has had no None of the possible answers are correct.

proven success.

Feedback: Subaerial volcanoes are volcanoes a) True that erupt on the Earth’s surface, or in the open b) False air “under the air”. They are commonly associated with convergent boundaries, where Feedback: Short-term prediction of

tectonic plates are moving towards each other. earthquakes is not usually possible. While

They are contrasted with submarine volcanoes, scientists can use seismometers to monitor

which erupt underwater, and subglacial seismic activity and look for patterns that may

volcanoes, which erupt under ice. Subaerial indicate an impending earthquake, there is no

volcanoes can produce different types of reliable way to predict exactly when or where an

eruptions and products, depending on the earthquake will occur.

 

125

Short-term prediction of imminent volcanic Feedback: Volcanic danger-assessment maps eruption has also had limited success. provide information about potential hazards

Scientists can use a variety of methods to associated with volcanic activity, such as lava

monitor volcanic activity, such as seismic flow paths, pyroclastic flow zones, ash fall

monitoring, ground deformation areas, and more. By understanding these measurements, and gas emissions, to look for hazards and having clear visual

signs of an impending eruption. However, there representations of the potential impact,

is no single method that is always reliable, and authorities can make informed decisions about

false alarms are common. evacuation plans, emergency response, and

-------------------------------------------------------------- risk management to protect communities at

638. Pyroclastic flows bring instant death to risk.

any life caught in them.

a) True

b) False

Feedback: Pyroclastic flows are incredibly fast-moving and highly destructive mixtures of hot

volcanic ash, rock fragments, and gas. They

can reach speeds of hundreds of kilometers per

hour and temperatures of several hundred

degrees Celsius. Due to their speed, high

temperature, and density, pyroclastic flows are

usually deadly to anything in their path, making

them one of the most dangerous volcanic

hazards. --------------------------------------------------------------

641. Volcanic ash and sulfur-rich aerosols

can absorb solar radiation and result in

cooler average temperatures worldwide.

a) True b) False

Feedback: Volcanic ash and sulfur-rich aerosols ejected into the atmosphere during

volcanic eruptions can indeed have a cooling

effect on global temperatures. These particles

can reflect and scatter sunlight, reducing the

amount of solar radiation that reaches the

-------------------------------------------------------------- Earth's surface. This phenomenon is known as

639. "volcanic winter." Historical records show that It is not possible to divert lava flows

because they’re too hot and powerful. major volcanic eruptions have led to temporary

a) decreases in global temperatures due to the True

b) presence of these particles in the atmosphere. False

An example is the 1815 eruption of Mount

Feedback Tambora, which resulted in the "Year Without a : While diverting lava flows can be

extremely challenging due to their high Summer" in 1816. temperatures and fluidity, it is not entirely

impossible. Various methods have been

attempted in the past to divert lava flows away

from populated areas or critical infrastructure.

These methods often involve creating barriers

or channels to redirect the flow, using

explosives to alter the lava's path, or cooling the

leading edge of the flow to slow its advance.

While success is not guaranteed and depends

on factors such as lava composition and flow

 

rate, attempts have been made to mitigate the -------------------------------------------------------------- impact of lava flows. 642. Physical disintegration of rock into -------------------------------------------------------------- smaller pieces is called: 640. Volcanic danger-assessment maps are a) Chemical weathering. valuable tools in protecting human life when b) Transportation. volcanic eruption threatens. c) Deposition. a) True d) Mechanical weathering. b) False

 

126

Feedback: The physical disintegration of rock minerals, leading to their dissolution and

into smaller pieces is referred to as mechanical breakdown. This makes carbonic acid one of

weathering. This process involves physical the most effective agents of chemical

forces that break down rocks into fragments weathering at Earth's surface. without changing their chemical composition.

 

643. The decomposition of rock from -------------------------------------------------------------- exposure to water and atmospheric gases is --------------------------------------------------------------

646. The most common end product of the

 

a) Chemical weathering. a) Clay minerals. b) called: chemical weathering of feldspar is:

c) Deposition. c) Amphibole. Mechanical weathering. Transportation. b) Pyroxene. d) d) Calcite.

 

Feedback: The decomposition of rock due to Feedback: The most common end product of exposure to water and atmospheric gases, the chemical weathering of feldspar, a common leading to changes in the rock's chemical mineral in many rocks, is clay minerals. composition, is known as chemical weathering. Feldspar minerals undergo chemical reactions This process involves chemical reactions that with water and other substances to break down break down minerals in the rock over time. into clay minerals, which are a major component of soil.

 

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

644. Which is NOT a type of mechanical

weathering?

a) Frost wedging.

 

c) Pressure release. -------------------------------------------------------------- d) b) Frost heaving.

Oxidation.

 

chemical weathering rather than a type of Clay minerals. b) Pyroxene. mechanical weathering. It involves the reaction c) Amphibole. of certain minerals with oxygen to form new d) Feedback chemical weathering of quartz is: : Oxidation is very important a) 647. The most common end product of the

compounds. The other options listed (frost Calcite. e) Quartz does not usually weather chemically. wedging, frost heaving, and pressure release)

 

down rocks without altering their chemical to chemical weathering due to its stable structure and composition. Unlike minerals like processes that involve physical forces breaking are examples of mechanical weathering Feedback: Quartz is a highly resistant mineral

 

645. unchanged during most chemical weathering The single most effective agent of processes. chemical weathering at Earth’s surface is : a) -------------------------------------------------------------- feldspar, quartz tends to remain largely composition.

Carbonic acid H 2CO3.

b) Water H2O.

c) Carbon dioxide CO2.

d) Hydrochloric acid HCl.

Feedback: Carbonic acid (H2CO3) is a weak acid formed when carbon dioxide (CO2) dissolves in water (H2O). It plays a significant role in chemical weathering by reacting with

minerals in rocks, particularly carbonate --------------------------------------------------------------

127

648. Soil with approximately equal amounts and plant material, is called the O horizon. This

of sand, silt, and clay along with a generous layer is also known as the "organic horizon" and

amount of organic matter is called: is typically found above the mineral layers (A,

a) Loam. B, and C horizons) in the soil profile. b) Inorganic.

c) Humus.

d) Caliche.

Feedback: Loam is often considered ideal for gardening and agriculture because it has good

water-holding capacity, drainage, and nutrient

content, making it suitable for a wide range of

plants.

 

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

651. Hardpan forms in the: a) A horizon.

-------------------------------------------------------------- b) B horizon. 649. The most important factor in c) C horizon.

determining the type of soil that forms is: d) O horizon.

a) Parent material.

b) Living organisms. Feedback: Hardpan is a compacted layer of c) Slope. soil that has become dense and impenetrable

d) Climate. due to factors such as pressure, compaction,

e) Time. and cementation. This layer restricts the

movement of water, air, and plant roots through

Feedback: Climate is the most important factor the soil, which can negatively impact drainage

in determining the type of soil that forms. and plant growth. Climate influences the rates of weathering, Hardpan is typically found in the B horizon of

organic matter decomposition, and overall soil the soil profile. The B horizon, also known as

development processes. The amount of rainfall, the "subsoil," is located beneath the A horizon

temperature, and other climatic conditions play (topsoil) and often contains accumulations of

a significant role in shaping the characteristics minerals leached down from above. In some

of soil, such as its texture, composition, and cases, these minerals can cement particles

fertility. Other factors, such as parent material, together, leading to the development of

living organisms, slope, and time, also hardpan. The hardpan layer can be a natural

contribute to soil formation, but climate often feature, but it can also be induced or

has the most profound and immediate impact. exacerbated by human activities such as

excessive tilling or heavy machinery use.

 

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

650. The soil horizon containing only --------------------------------------------------------------

organic material is the: 652. Which one of the following is a

a) A horizon. chemical weathering process? b) B horizon. a) Lithification. c) C horizon. b) Oxidation. d) O horizon. c) Frost wedging. e) E horizon. d) Pressure release.

e) Compaction.

Feedback: The soil horizon containing only organic material, such as decomposed leaves

128

Feedback: Oxidation is a chemical weathering e) Corners and edges of stones weather faster process. It involves the reaction of minerals with than flat surfaces. oxygen, often resulting in the formation of new

compounds. This process can lead to changes Feedback: Spheroidal weathering is a form of in the mineral composition and color of rocks chemical weathering that affects jointed

and minerals over time. The other options listed bedrock and results in the formation of

(a: lithification, c: frost wedging, d: pressure concentric or spherical layers of highly decayed

release, e: compaction) are primarily rock within weathered bedrock that is known as

associated with physical weathering rather than saprolite. It occurs because the corners and

chemical weathering. edges of stones weather faster than flat

surfaces. Thermal expansion and contraction

are not the main cause of spheroidal

weathering. Aluminum oxides are not insoluble.

Oxidation does not change limestone to

dolostone. Rounding does not take place

rapidly during transport.

 

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

653. The type of soil found in the semiarid

and arid regions is:

a) Breccia.

b) -------------------------------------------------------------- Laterite.

c) 655. Exfoliation domes form by a Pedocal.

d) mechanical weathering process called: Regolith.

e) a) Pressure release. Detrital.

b) Salt crystal growth.

Feedback c) Hydrolysis. : Pedocal soils are characterized by a relatively high content of calcium carbonate d) Regression. (lime) and are often alkaline in nature. These e) Granitization. soils can form in dry environments where

evaporation is high, leading to the accumulation Feedback: Exfoliation domes form through the of minerals like calcium carbonate in the upper mechanical weathering process known as

soil layers. This contributes to the characteristic pressure release or unloading. Over time, as

properties of pedocal soils in these regions. erosion removes overlying rock layers, the

pressure on deeper rocks decreases. This

decrease in pressure can cause the outer

layers of rocks to expand and crack, leading to

the formation of dome-like structures.

 

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

654. Spheroidal weathering takes place

because:

a) Thermal expansion and contraction are so

effective.

b) Aluminum oxides are nearly insoluble.

c) Oxidation changes limestone to dolostone. d) Rounding takes place rapidly during

transport. --------------------------------------------------------------

 

129

656. Which is characteristic of soil horizons? e) Parent material. a) They can be distinguished from one another

by appearance and chemical composition. Feedback: Regolith is the unconsolidated layer

b) Boundaries between soil horizons are of rock and mineral fragments that covers the

usually transitional rather than sharp. Earth's surface. It is formed by the physical and

c) They are classified by letters. chemical weathering of rocks. Regolith can be

d) All of the preceding. found on both land and sea, and it is typically

only a few meters thick.

Feedback: Soil horizons are layers of soil that have different physical and chemical

properties. They are classified by letters, and

the boundaries between horizons are usually

transitional rather than sharp. Soil horizons can

be distinguished from one another by their

appearance and chemical composition. For

example, the O horizon is typically dark in color

and high in organic matter, while the B horizon

is typically lighter in color and higher in mineral

 

particles and clay. Soil horizons play an -------------------------------------------------------------- important role in plant growth. The topsoil 659. The source of energy that drives horizon is where most of the nutrients and water Earth's external processes is: are found, and the subsoil horizon helps to a) Nuclear fission. store water and nutrients. b) Wind. -------------------------------------------------------------- c) The Sun. 657. A marine transgression yields a vertical d) Gravity. sequence: e) None of the above. a) Of rounded domes of rock with sheet joints. b) That includes interlayered igneous and Feedback : The primary source of energy that metamorphic rocks. drives Earth's external processes, such as c) With offshore facies overlying nearshore weathering, erosion, and the water cycle, is the facies. Sun. Solar energy fuels processes like d) Of evaporates, granite, and parent material. evaporation, which leads to the formation of e) Of delta deposits overlain by turbidities. clouds and precipitation, as well as the

Feedback movement of wind and ocean currents. : A marine transgression occurs when sea level rises, causing marine

environments to advance over the land. This

can result in a vertical sequence of sedimentary

rocks, with offshore facies (deposits from

deeper marine environments) overlying

nearshore facies (deposits from shallower

marine environments). This sequence reflects

the migration of marine environments towards

the land as sea level rises.

 

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

660. The physical removal of material by

mobile agents such as water, wind, or ice is

referred to as __________.

a) Erosion. b) weathering

-------------------------------------------------------------- c) diagenesis 658. The unconsolidated material covering d) mass wasting

much of Earth’s land surface, as well as e) none of the above most of the seafloor, is called:

a) Regolith. Feedback: Erosion is the process by which b) Conglomerate. material is worn away from one place and

c) transported to another by wind, water, or ice. Limestone.

d) Erosion is a major force in shaping the Earth's Rock gypsum.

130

surface. It can create valleys, canyons, and hardness scale; it is used as crushed stone

other landforms. Erosion can be classified into media in sewage system drain fields and as a

two main types: mechanical erosion and base material for foundations and construction

chemical erosion. Erosion is an important slabs due to its durability (very resistant to

process in the rock cycle. It helps to break down weathering). rocks and minerals into smaller pieces, which

can then be transported and deposited to form

new sedimentary rocks.

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

663. What type of weathering produces the

"rounding" of a rock?

a) Jointing. b) Circular. c) Columnar. d) Spheroidal. e) Exfoliation.

Feedback: Spheroidal weathering is a type of

-------------------------------------------------------------- mechanical weathering that produces the

661. In nature, both types of weathering "rounding" of a rock. This process occurs when

usually work simultaneously. corners and edges of rocks are weathered

a) True more rapidly than flat surfaces, leading to the

b) False gradual formation of rounded shapes.

Spheroidal weathering often results from the

Feedback: In nature, both mechanical differential expansion and contraction of

(physical) and chemical weathering processes minerals within the rock due to temperature

usually work simultaneously. These processes changes. often complement each other and contribute to

the breakdown and alteration of rocks and

minerals. Mechanical weathering can create

smaller particles and expose more surface area

to chemical reactions, while chemical

weathering can weaken minerals and make

them more susceptible to physical breakdown.

 

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

664. Mechanical weathering includes: a) Unloading. b) Thermal expansion. c) Biological activity. d) Frost wedging. e) All of the above.

 

-------------------------------------------------------------- Feedback: Mechanical weathering is the process by which rocks are broken down into 662. Based on your knowledge of how smaller pieces without changing their chemical rapidly different minerals weather, which of composition. It is caused by physical forces, these rock types would provide the most such as temperature changes, pressure suitable foundation base for a home built in changes, and biological activity. the tropics? a) Limestone. b) Basalt. c) Granite. d) Mafic volcanic breccia. e) Andesite.

Feedback: Granite composed primarily of feldspar, quartz, and mica, being an igneous

rock (formed from volcanic activity), millions of

years of compression and heat below the

earth's surface turned them into stone. Granite

is one of the hardest stones available, having a

rating of 7 on the Moh's Measurement of --------------------------------------------------------------

131

665. The physical breakdown and chemical accelerate the breakdown of rocks at or near

alteration of rock at or near Earth's surface Earth's surface. is called erosion.

a) True

b) False

Feedback: The physical breakdown and chemical alteration of rock at or near Earth's

surface is known as weathering, not erosion.

Weathering involves processes that break

down rocks into smaller particles and alter their

mineral composition. Erosion, on the other

hand, involves the transport of these weathered -------------------------------------------------------------- particles by agents such as water, wind, ice, or 668. Do you expect these faulted rocks to be gravity. While weathering prepares rocks for more easily weathered or less easily erosion, erosion is the actual movement of the weathered than non-faulted rocks? fragmented material. a) The faulted rocks are more easily

weathered.

b) The faulted rocks are less easily weathered. c) It is too difficult to tell from the information

given.

Feedback: Highly jointed or faulted rocks are usually more intensely weathered along the

lines of weakness in the rock mass.

Consequently, these softer weathered materials are more easily

-------------------------------------------------------------- eroded out, with the result that river valleys are 666. usually located along the line of a major fault or Frost wedging is most effective in the

polar latitudes. joint set.

a) True

b) False

Feedback: Frost wedging, also called ice wedging, is the process by which water seeps

into cracks in a rock, expands on freezing, and

thus enlarges the cracks. The effectiveness of

frost wedging is related to the frequency of

freezing and thawing. Frost wedging is most

effective in mountainous climates.

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

669. When granite is chemically weathered,

quartz ________.

a) Remains virtually unchanged. b) Is converted into kaolinite. c) Is changed into oxides. d) Becomes mica.

 

b) True weathering processes. Its resistance to False chemical reactions and its hardness make it less prone to breaking down or undergoing Feedback : Biological activity can have a significant changes. In addition to its role in significant influence on the process of resisting weathering, quartz can also contribute weathering. Plants, animals, and to mechanical weathering as it becomes part of microorganisms play a role in both physical and processes like abrasion and the grinding action 667. Biological activity has little influence on Feedback: Quartz is one of the most stable the process of weathering. minerals in both chemical and mechanical a) -------------------------------------------------------------- e) None of the above.

 

chemical weathering. Plant roots can grow into of wind-blown sand. cracks in rocks, exerting physical pressure and --------------------------------------------------------------causing them to break apart. Microorganisms 670. Oxidation is an important mechanism in can release acids that contribute to chemical decomposing such ferromagnesian weathering. Over time, biological activity can minerals as olivine, pyroxene, and hornblende.

 

132

a) True determines how quickly rocks and minerals

b) False break down at or near Earth's surface.

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

Feedback: Ferromagnesian minerals as 673. In Bowen's reaction series, the olivine, pyroxene, and hornblende contain iron minerals that form last are the most

and magnesium, which are susceptible to susceptible to chemical weathering. oxidation when exposed to oxygen and water. a) True This process can lead to the breakdown of b) False these minerals and the formation of new

compounds. Feedback: The minerals that form last are the

most stable and resistant to chemical

weathering. These are the felsic minerals, such

as quartz, muscovite, and orthoclase that

crystallize at low temperatures. The minerals

that form first are the most unstable and

susceptible to chemical weathering. These are

the mafic minerals, such as olivine, pyroxene,

and amphibole that crystallize at high

-------------------------------------------------------------- temperatures. 671. Quartz is less resistant to chemical

weathering than feldspar.

a) True

b) False

Feedback: Quartz, whether vein deposits or individual grains, undergoes

practically no chemical weathering; the end

product is quartz sand. Some of

the feldspars weather to clay and release

calcium, sodium, silica, and many other

elements that are transported in water. --------------------------------------------------------------

674. Rain is naturally acidic because it

contains weak __________ acid.

a) Acetic. b) Citric. c) Nitric. d) Sulfuric. e) None of the above.

Feedback: Rain is naturally acidic because it contains weak carbonic acid. Carbon dioxide

(CO 2) dissolves in water to form carbonic acid (H2CO3). The pH of rainwater is typically around

-------------------------------------------------------------- 5.6, which is slightly acidic. Acetic acid, citric

672. What factor(s) control the rate of acid, and nitric acid are all strong acids. They

weathering? are not found in rainwater in significant

a) Moisture. amounts. b) Mineral makeup.

c) Surface temperature.

d) Particle size.

e) All of the above.

Feedback: All the factors listed-moisture,

 

mineral makeup, surface temperature, and -------------------------------------------------------------- particle size can influence the rate of 675. Soils formed from bedrock are called weathering. Moisture enhances chemical residual soils. reactions, mineral makeup determines a) True susceptibility to weathering, surface b) False temperature affects the rates of chemical reactions, and particle size influences the Feedback : Soils that are formed from the surface area available for weathering weathering and decomposition of the processes. The combination of these factors underlying bedrock are called residual soils. These soils develop in place as the bedrock

133

weathers and breaks down, contributing the "subsoil." It's located beneath the A horizon

minerals and nutrients to the soil profile. (topsoil) and can contain accumulations of

minerals leached down from above. The

topsoil, or A horizon, is usually the uppermost

layer of soil and contains organic matter,

nutrients, and biological activity.

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

679. About 50% of the total volume of a

good quality soil consists of pore spaces.

a) True b) False

Feedback: These pore spaces are essential for holding air and water, which are crucial for plant

growth, nutrient movement, and microbial

activity within the soil.

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

676. Which of the following minerals is most

resistant to weathering in the conditions

found on Earth's surface?

a) Potassium feldspar.

b) Pyroxene.

c) Quartz.

d) Olivine.

e) Biotite mica.

Feedback: Quartz is the most resistant mineral

 

to weathering in the conditions found on Earth's -------------------------------------------------------------- surface. It is a hard, durable mineral that is not 680. Eluviation and leaching are most active easily dissolved by water or acids. Quartz is in the E horizon. also resistant to thermal expansion and a) True contraction, which makes it less likely to crack b) False due to temperature changes. -------------------------------------------------------------- Feedback : Eluviation and leaching, which 677. Which of the following is a component involve the downward movement of dissolved of soil? materials and minerals from upper soil horizons a) Humus. to lower ones, are most active in the E horizon. b) Water. The E horizon is characterized by the leaching c) Disintegrated and decomposed rock. of minerals and nutrients due to the percolation d) Decayed organic matter. of water through the soil profile. This process e) All of the above. contributes to the development of distinct soil

 

Feedback horizons and can lead to the accumulation of : Humus is a dark, organic matter certain minerals in the B horizon. that is formed by the decomposition of plants and animals. It is rich in nutrients and helps to improve soil structure. Water is essential for plant growth and helps to transport nutrients to

plant roots. Disintegrated and decomposed

rock provides the mineral nutrients that plants

need to grow. Decayed organic matter provides

nutrients for plants and helps to improve soil

structure. The relative proportions of these

components vary depending on the type of soil.

For example, sandy soils have a higher

proportion of mineral matter, while clay soils

have a higher proportion of organic matter.

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

678. The B horizon of a soil is also called the --------------------------------------------------------------

topsoil. 681. The optimum environment for chemical

a) True weathering is a combination of warm

b) False temperatures and abundant moisture.

a) True

Feedback: The B horizon of a soil is not called b) False the topsoil. The B horizon is often referred to as

134

Feedback: Higher temperatures accelerate horizon, which is located beneath the A horizon

chemical reactions, and moisture provides the and often contains accumulations of minerals

medium through which these reactions can take leached down from above. place. In such conditions, minerals are more --------------------------------------------------------------

likely to undergo dissolution, oxidation, 685. The same parent material will always hydrolysis, and other chemical processes that produce the same type of soil. lead to their decomposition and alteration. a) True -------------------------------------------------------------- b) False 682. In general, the greater the slope, the

thicker the soil. Feedback: The same parent material can

a) True produce different types of soil based on other

b) False factors such as climate, vegetation,

topography, and time. These factors influence

Feedback: On steeper slopes, the the processes of weathering, erosion, and soil accumulation of soil can be limited due to formation, leading to variations in soil properties

increased erosion and gravitational forces that even when the parent material is the same. As

can transport soil downslope. This can result in a result, soils formed from the same parent

thinner soil profiles compared to flatter areas material can exhibit differences in texture,

where soil has a better chance to accumulate composition, and other characteristics. and develop over time. --------------------------------------------------------------

686. The greatest amount of soil erosion is

caused by wind.

a) True b) False

Feedback: The greatest amount of soil erosion is typically caused by water, not wind. Water

 

-------------------------------------------------------------- erosion, driven by rainfall and flowing water, is generally more effective in transporting and 683. The layer of rock and mineral eroding soil compared to wind erosion. While fragments produced by weathering is wind erosion can be significant in certain arid or referred to as: semi-arid regions, water erosion is generally a) Subsoil. responsible for the majority of soil erosion on a b) Zone of leaching. global scale. c) Regolith. d) Soil. e) Humus.

Feedback: Regolith includes both the unconsolidated material at the Earth's surface

and the partially weathered bedrock beneath it.

Soil is a more specific term that refers to the

combination of mineral particles, organic

matter, water, and air that forms on the regolith

as a result of weathering processes. --------------------------------------------------------------

687. Removing vegetation will generally

increase the rate of soil erosion.

a) True b) False

Feedback: Removing vegetation can increase the rate of soil erosion. Vegetation, especially

plants with roots, helps stabilize the soil by

-------------------------------------------------------------- binding it together and providing cover against

 

a) what is commonly called the subsoil. more exposed to the forces of erosion, True including wind and water. The roots of plants b) 684. the impact of raindrops and flowing water. The O and A horizons of a soil make up When vegetation is removed, the soil becomes

False also contribute to soil structure and cohesion,

Feedback reducing the likelihood of soil being easily : The O horizon is the organic carried away by erosion.

 

horizon, commonly referred to as the "organic -------------------------------------------------------------- layer," and the A horizon is the topsoil layer. 688. If the pressure increases, what The subsoil is typically composed of the B happens to the melting point of ice?

135

a) Increases. with high clay content can become waterlogged

b) Decreases. and less suitable for many plants. c) Stays the same.

Feedback: When pressure increases, the melting point of ice decreases. This is because

the increased pressure forces the molecules of

water closer together, making it harder for them

to break apart and form liquid water. The

opposite is true for the boiling point of water.

When pressure increases, the boiling point of

water increases. This is because the increased

pressure makes it harder for water vapor to

escape from the liquid. The melting and boiling --------------------------------------------------------------

 

which the substance changes from a solid to a water as the pressure decreases? Increases. points of a substance are the temperatures at 691. What happens to the boiling point of

liquid and from a liquid to a gas, respectively. a) The melting point of a substance is always b) Decreases. lower than its boiling point. c) Stays the same.

Feedback: As the pressure decreases, the boiling point of water also decreases. At lower

pressure, water molecules require less energy

to escape the liquid state and transition into

vapor. This is why water can boil at lower

temperatures at higher altitudes where

atmospheric pressure is lower.

 

689. At 1 atmosphere total pressure water o cannot be heated above 100-------------------------------------------------------------- C. At that

temperature water is converted to steam

(vapor), water can be heated to higher

temperatures by: --------------------------------------------------------------

a) Increasing the pressure. 692. In which of the following climates will b) Decreasing the pressure. chemical weathering be most rapid? c) Increasing the temperature. a) Hot and dry.

b) Hot and humid.

Feedback: Water at 1 atmosphere of pressure c) Cold and dry. (standard atmospheric pressure) boils at d) Cold and humid. 100°C. To heat water to higher temperatures

while it remains in the liquid state, you would Feedback: Chemical weathering is the process need to increase the pressure. This is why of breaking down rocks by chemical reactions.

pressure cookers, which increase the pressure These reactions are more likely to occur in hot

inside the cooking vessel, allow water to reach and humid climates because the water

higher temperatures before boiling. molecules can dissolve the minerals in the

-------------------------------------------------------------- rocks. In addition, the heat in hot climates also

690. Excessive clay in soil will result in poor speeds up the chemical reactions.

drainage. --------------------------------------------------------------

a) True 693. Mechanical weathering produces: b) False a) Clay minerals.

b) Quartz.

Feedback: Clay particles have small sizes and c) Smaller particles. tend to pack closely together, creating a dense d) Calcium carbonate. structure with limited pore spaces. This

compacted structure reduces the movement of Feedback: Mechanical weathering involves the water through the soil, leading to poor drainage physical breakdown of rocks into smaller

and increased water retention. As a result, soils particles without changing their chemical

 

136

composition. This can occur through processes in the rock cycle. It breaks down large rocks into

like frost wedging, abrasion, and exfoliation. smaller pieces, which can then be transported

The result of mechanical weathering is the and deposited to form new sedimentary rocks.

production of smaller rock fragments and Weathering also helps to create soil, which is

particles. essential for plant growth.

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

696. Soil is composed of ____________. a) Organic matter produced by organisms. b) Fragments of bedrock. c) Clay minerals formed by the chemical

alteration of bedrock.

d) All of these.

Feedback: Soil is composed of organic matter produced by organisms, fragments of bedrock,

and clay minerals formed by the chemical

alteration of bedrock. Organic matter includes

dead and decaying plants and animals, as well

 

-------------------------------------------------------------- as the waste products of organisms. It provides nutrients for plants and helps to improve soil 694. When liquid water freezes: structure. Fragments of bedrock are the result a) It does not change in volume. of physical weathering processes, such as b) It expands by 5% in volume. erosion and temperature changes. They can be c) It expands by 9% in volume. of different sizes, from sand grains to boulders. d) It decreases in volume. Clay minerals are formed by the chemical alteration of bedrock. They are very small Feedback : The more common understanding particles that have a high surface area. This of the expansion of water when it freezes is due allows them to hold water and nutrients, which to the hydrogen bonding between water makes them important for plant growth. molecules. Unlike many substances, the solid

form of water (ice) is less dense than its liquid

form. This expansion happens because the

arrangement of water molecules in the solid

state forms a hexagonal lattice structure with

open spaces, creating a less compact

arrangement than in the liquid state.

This expansion is why ice floats on water, as it's

less dense and occupies more volume. It's also

why freezing water can be damaging to pipes,

containers, and other structures, as the

expansion can cause them to crack or rupture.

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

697. Which of the following statements

about weathering is FALSE?

a) Rocks of different compositions weather at

different rates.

b) Heat and heavy rainfall increase the rate of

chemical weathering.

c) The presence of soil slows down the

-------------------------------------------------------------- weathering of the underlying bedrock. 695. What is the term for the general d) The longer a rock is exposed at the surface,

process by which rocks are broken down at the more weathered it becomes. the Earth's surface?

a) Deposition. Feedback: Soil is actually a product of b) Erosion. weathering. Soil actually accelerates c) Lithification. weathering of underlying bedrock due to the

d) Weathering. presence of water, gases, and organic acids.

The other statements are true.

Feedback: Weathering is the general process --------------------------------------------------------------

by which rocks are broken down at the Earth's 698. Which of the following minerals has a surface. It is caused by physical and chemical low solubility and therefore is least

processes, such as temperature changes, susceptible to chemical weathering at the

pressure changes, and the presence of water Earth's surface? and acids. Weathering plays an important role

137

a) Calcite. c) 10 % b) Plagioclase. d) 25 % c) Quartz.

d) Olivine. Feedback: Carbon dioxide is a trace gas in the

Earth's atmosphere, making up about 0.04% by

Feedback: Quartz is the most resistant mineral volume. It is a greenhouse gas that traps heat

to chemical weathering at the Earth's surface. It in the atmosphere, contributing to climate

is a hard, durable mineral that is not easily change. Carbon dioxide levels in the

dissolved by water or acids. Quartz is also atmosphere have been increasing since the

resistant to thermal expansion and contraction, Industrial Revolution, due to human activities

which makes it less likely to crack due to such as burning fossil fuels and deforestation.

temperature changes. Quartz is a common This increase in carbon dioxide levels is one of

mineral in many different types of rocks, the main causes of climate change. including igneous rocks, metamorphic rocks,

and sedimentary rocks.

 

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

699. The rate of chemical weathering is 702. Carbonic acid, the primary agent of

increased by acids. The most common chemical weathering is produced by _____.

natural acid on the Earth's surface is ____ . a) Carbon dioxide dissolving in rainwater.

a) Nitric. b) Plant roots. b) Hydrochloric. c) Bacteria that feed on plant and animal c) Carbonic. remains. d) Sulfuric. d) All of these.

Feedback: Carbonic acid is the most abundant Feedback: Carbonic acid is the primary agent and important natural acid that increases the of chemical weathering. It is produced by the

rate of chemical weathering on the Earth's dissolution of carbon dioxide in rainwater, the

surface. Carbonic acid is formed when carbon release of carbon dioxide by plant roots, and

dioxide from the atmosphere or soil air the release of carbon dioxide by bacteria that

dissolves in water: feed on plant and animal remains. Carbonic

CO2 + H2O ֖ H2CO3 acid is a weak acid, but it is strong enough to

Carbonic acid reacts with and dissolves silicate dissolve many minerals, including calcite,

minerals in rocks during chemical weathering. dolomite, and feldspar. Chemical weathering by

-------------------------------------------------------------- carbonic acid is important in the formation of

700. Which of these is least likely to form a soil and caves.

clay mineral during weathering? --------------------------------------------------------------

a) Feldspar. 703. Which of the processes is NOT an b) Quartz. example of chemical weathering? c) Amphibole. a) Dissolution of calcite. d) Olivine. b) Breakdown of feldspar to form clay.

c) Splitting of a rock along a fracture.

Feedback: Quartz is the least likely to form a d) Rusting of a nail. clay mineral during weathering. Quartz is a very

stable mineral and is resistant to chemical Feedback: Splitting of a rock along a fracture is weathering processes that lead to the formation not an example of chemical weathering; it is a

of clay minerals. In contrast, minerals like mechanical or physical process. This type of

feldspar, amphibole, and olivine are more weathering occurs when rocks break or fracture

susceptible to weathering and can break down due to physical forces such as temperature

to form clay minerals under certain conditions. changes, frost action, pressure, or impacts.

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

701. Carbon dioxide makes up about 704. Caves are most likely to form in which

_______ of the Earth's atmosphere. of the following rock types?

a) 0.04 % a) Granite. b) 1 % b) Limestone.

 

138

c) Basalt. weathered, it is broken down into smaller

d) Sandstone. pieces of granite, as well as sand and silt. When

granite is chemically weathered, the feldspar

Feedback: Caves are most likely to form in and ferromagnesian silicates in the rock are

limestone rock. Limestone is a sedimentary broken down into clays and ions dissolved in

rock primarily composed of calcium carbonate. water. It is soluble in slightly acidic groundwater, which --------------------------------------------------------------

can lead to the formation of underground caves 707. The deep red color of soils found in through a process called dissolution. Over time, warm, humid regions, caused by ______.

water can dissolve the limestone and create a) Reduced iron oxides. intricate cave systems. Granite, basalt, and b) Oxidized iron oxides. sandstone are less likely to form caves through c) Quartz. this dissolution process. d) Feldspar.

Feedback: The deep red color of soils found in warm, humid regions is typically caused by

oxidized iron oxides. These iron oxides,

commonly referred to as "rust," can give the soil

a reddish hue when they are exposed to oxygen

and undergo oxidation. This process is

especially prevalent in regions with warm and

humid conditions, where the breakdown of

minerals in the soil results in the release of iron

ions that can readily react with oxygen in the

presence of water to form the characteristic red

-------------------------------------------------------------- iron oxide color. 705. As a rock breaks into smaller pieces,

the surface area to volume ratio ______.

a) Increases.

b) Decreases.

c) Stays the same.

d) Can increase or decrease depending on the

size of the pieces.

Feedback: As a rock breaks into smaller pieces, the surface area to volume ratio

 

increases. This is because the surface area of -------------------------------------------------------------- the smaller pieces becomes relatively larger 708. Which of the following factors would compared to their volume. This increase in increase the rate of weathering? surface area can lead to more efficient chemical a) Increasing rainfall. weathering processes, as there is more b) Increasing temperature. exposed surface area for chemical reactions to c) Increasing organic activity. take place. d) All of these.

Feedback: The rate of weathering is increased by increasing rainfall, increasing temperature,

and increasing organic activity. These factors

increase the amount of water, energy, and

acids available for chemical weathering

 

706. The physical and chemical weathering weathering, with some rocks being more of a granite will produce ________. resistant to weathering than others. a) Ions dissolved in rainwater and soil water. -------------------------------------------------------------- -------------------------------------------------------------- weathered also plays a role in the rate of reactions to occur. The type of rock being

 

b) Mineral fragments and granite fragments. 709. The major source of aluminum metal, c) Clays and iron oxides. _______, is a clay-rich ore composed of d) All of these. aluminum hydroxide. a) Hematite. Feedback : The physical and chemical b) Bauxite. weathering of granite will produce ions c) Kaolinite. dissolved in rainwater and soil water, mineral d) Montmorillonite. fragments and granite fragments, and clays and iron oxides. When granite is physically

 

139

Feedback: Bauxite is the major source of general term for the mixture of mineral particles,

aluminum metal. It is a clay-rich ore composed organic matter, and other components in the

of aluminum hydroxide minerals, along with upper layer of the Earth's surface. various impurities. Bauxite is the primary --------------------------------------------------------------

source for the extraction of aluminum, which is 712. Which of the following minerals is most a widely used metal in various industries. stable at the Earth's surface? Hematite is an iron ore, while kaolinite and a) Hematite. montmorillonite are types of clay minerals but b) Mica. not the major sources of aluminum metal. c) Olivine.

d) Feldspar.

Feedback: Hematite, with the chemical formula Fe 2O3 is a mineral that forms at high temperatures and pressures, but is also very

stable at the Earth’s surface. Hematite is resistant to chemical weathering and does not

dissolve easily in water or acids. Hematite is

also one of the most common minerals in soils

 

-------------------------------------------------------------- and sediments. +3 710. Fe refers to ________. a) Iron metal. b) Ferrous iron. c) Ferric iron. d) Hematite.

Feedback: Fe+3 refers to ferric iron, which is iron in its +3 oxidation state. This means that

 

in a positive charge of +3. It is commonly 713. A substance that releases hydrogen +3 denoted as Fe and is associated with ions (H the iron atom has lost three electrons, resulting --------------------------------------------------------------

+) to a solution is called a(n) ______.

compounds and minerals containing iron in this a) Oxidizer. oxidation state. Hematite, for example, is an b) Reducer. iron oxide mineral that contains ferric iron and c) Acid. is often referred to as Fe2O3, where the 3 d) Pedalfer. indicates the oxidation state of the iron. Ferrous

iron (Fe+2) refers to iron in its +2 oxidation state. Feedback: A substance that releases

hydrogen ions (H+) to a solution is called an acid. Acids are characterized by their ability to

donate protons (H+ ions) to other substances, which results in the formation of hydronium ions

(H3O+) in aqueous solutions. This release of hydrogen ions is what gives acids their

characteristic properties, such as sour taste

and the ability to react with bases.

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711. What is the term geologists use for the

layer of loose, heterogeneous weathered

material lying on top of the bedrock?

a) Humus.

b) Laterite.

c) Regolith.

d) Soil.

Feedback: Geologists use the term "regolith" to

 

refer to the layer of loose, heterogeneous -------------------------------------------------------------- weathered material that lies on top of the 714. Which of the following farming bedrock. This layer includes various sizes of practices helps to prevent the erosion of particles, such as rock fragments, minerals, and topsoil? organic matter. It is the result of weathering a) Plowing a field perpendicular to the contour processes acting on the bedrock over time. lines. Humus refers specifically to the organic b) Plowing a field parallel to the contour lines. component of soil, laterite is a type of soil c) Plowing a field in the direction that the water formed in tropical climates, and soil is a more drains.

 

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d) None of these will help prevent soil erosion. dissolved minerals, and pedalfers (d) are soils

rich in aluminum and iron oxides.

Feedback: Plowing a field parallel to the --------------------------------------------------------------

contour lines is a farming practice that helps 717. Which of the following minerals found prevent the erosion of topsoil. This practice is in a granite is not altered by chemical

known as contour plowing. By plowing along weathering? the contour lines, water runoff is slowed down a) Biotite. and directed horizontally along the slope, b) Feldspar. reducing the speed and erosive power of the c) Magnetite. water. This helps to prevent the loss of topsoil d) Quartz. through erosion. Plowing a field in the direction

that the water drains (c) can exacerbate Feedback: Quartz is the mineral found in erosion, and plowing perpendicular to contour granite that is not significantly altered by

lines (a) is less effective at preventing soil chemical weathering. Quartz is a very durable

erosion. mineral that is resistant to most chemical

reactions that commonly occur during

weathering processes. While other minerals

like biotite and feldspar in granite are more

susceptible to chemical weathering, quartz

remains relatively stable and is often one of the

last minerals to be weathered in geological

processes.

 

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715. In the atmosphere, carbonic acid forms

from the reaction of carbon dioxide and ___.

a) Fossil fuels.

b) Nitrogen.

c) Oxygen.

d) Water.

 

Feedback -------------------------------------------------------------- : Carbon dioxide dissolves in water, Which of the following factors would 718. forming carbonic acid through the following increase the chemical weathering rate? reaction: a) Increasing rainfall. CO 2 + H 2 O ֖ H 2 CO 3 b) Increasing temperature. c) Increasing organic activity. d) All of these.

Feedback: Increasing rainfall, increasing temperature, and increasing organic activity