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Weathering is defined as the deterioration of materials that occurs *in situ*, distinguishing it from erosion which involves material transport.
Answer: True
Explanation: The definition of weathering emphasizes its *in situ* nature, meaning it occurs on-site with minimal material movement, in contrast to erosion which involves the transport of weathered materials.
Physical weathering primarily involves chemical reactions that alter the composition of rocks, leading to the formation of new minerals.
Answer: False
Explanation: Physical weathering is characterized by mechanical breakdown without chemical change, whereas chemical weathering involves altering the composition of rocks and forming new minerals.
Atmospheric oxygen and carbon dioxide are significant agents exclusively for chemical weathering processes, not physical weathering.
Answer: False
Explanation: Atmospheric oxygen and carbon dioxide are significant agents for both chemical weathering and, indirectly, physical weathering, as they contribute to the formation of acids that can weaken rock structures.
Weathering is a critical component of the rock cycle, contributing to the formation of sedimentary rock which covers a large portion of Earth's surface.
Answer: True
Explanation: Weathering is an essential part of the rock cycle, as the breakdown of rocks provides the material for sedimentary rock, which extensively covers Earth's surface.
Physical and chemical weathering rarely occur together, as their mechanisms are entirely independent.
Answer: False
Explanation: Physical and chemical weathering frequently occur together and often interact, with physical weathering increasing the surface area exposed to chemical agents, thereby accelerating chemical breakdown.
What is the primary distinction between weathering and erosion?
Answer: Weathering occurs *in situ* with little to no material movement, while erosion involves material transport.
Explanation: The fundamental distinction is that weathering is the *in situ* breakdown of materials, whereas erosion involves the subsequent transport of these materials.
Which of the following is identified as the principal agent for both physical and chemical weathering?
Answer: Water
Explanation: Water is identified as the principal agent driving both physical and chemical weathering processes.
How does physical weathering contribute to the acceleration of chemical weathering?
Answer: It enlarges cracks in rocks, increasing the surface area exposed to chemical agents.
Explanation: Physical weathering accelerates chemical weathering by enlarging cracks in rocks, which increases the surface area available for chemical reactions.
Physical weathering is also known as mechanical weathering and typically involves mechanical effects like expansion and contraction due to temperature fluctuations.
Answer: True
Explanation: Physical weathering is synonymous with mechanical weathering and is characterized by mechanical effects such as the expansion and contraction of rocks caused by temperature changes.
Frost weathering is considered the most important form of physical weathering, with plant roots and burrowing animals also contributing.
Answer: True
Explanation: Frost weathering is recognized as the most significant form of physical weathering, complemented by biological factors such as the wedging action of plant roots and the burrowing activities of animals.
Frost wedging, where expanding porewater upon freezing widens cracks, is currently understood to be the most significant mechanism of frost weathering.
Answer: False
Explanation: While frost wedging was historically considered the main mechanism, current research indicates that ice segregation, involving the formation of ice lenses, is a more significant mechanism of frost weathering.
The volume increase of water upon freezing can generate pressures sufficient to fracture granite, whose tensile strength is approximately 4 megapascals.
Answer: True
Explanation: Water's 9.2% volume increase upon freezing can generate pressures up to 14 megapascals, which is sufficient to fracture granite, given its tensile strength of approximately 4 megapascals.
Frost wedging is most effective in large, open fractures within unsaturated rock, allowing ice to expand freely.
Answer: False
Explanation: Frost wedging is most effective in small, tortuous fractures within rock that is almost completely saturated with water, as this prevents ice from expanding freely into air spaces and allows pressure to build.
Ice segregation involves supercooled water migrating to form ice lenses, exerting pressure up to ten times greater than frost wedging.
Answer: True
Explanation: Ice segregation involves supercooled water migrating to form ice lenses, which can exert pressures significantly greater than those produced by frost wedging, up to ten times more.
Thermal stress weathering is exclusively caused by intense solar heating, making it irrelevant in cold climates.
Answer: False
Explanation: Thermal stress weathering can be caused by any large temperature change, not solely by intense solar heating, and is also a significant process in cold climates, making the term 'insolation weathering' misleading.
Early 20th-century experiments accurately replicated natural stress conditions for thermal stress weathering, leading geologists to discount its importance.
Answer: False
Explanation: Early 20th-century experiments on thermal stress weathering are now criticized for failing to accurately replicate natural stress conditions, leading to an underestimation of its importance by geologists for a long time.
Pressure release weathering, or unloading, causes rocks to expand and form fractures parallel to the surface, leading to exfoliation.
Answer: True
Explanation: Pressure release weathering, also known as unloading, occurs when overlying rock material is removed, causing deeply buried rocks to expand and form fractures parallel to the surface, a process known as exfoliation or sheeting.
Salt crystallization weathering is most common in humid, tropical climates due to abundant rainfall.
Answer: False
Explanation: Salt crystallization weathering is most prevalent in arid climates with strong evaporation and along coastlines, not in humid, tropical climates.
What is currently considered a more significant mechanism of frost weathering than frost wedging?
Answer: Ice segregation
Explanation: Current research indicates that ice segregation, involving the formation of ice lenses, is a more significant mechanism of frost weathering than frost wedging.
What is the approximate tensile strength of granite, making it susceptible to fracturing by freezing water?
Answer: 4 megapascals
Explanation: The tensile strength of granite is approximately 4 megapascals, which makes it susceptible to fracturing by the pressures generated from freezing water.
Under what conditions is frost wedging most effective?
Answer: In small, tortuous fractures within rock that is almost completely saturated with water.
Explanation: Frost wedging is most effective in small, tortuous fractures within rock that is almost completely saturated with water, as this allows pressure to build without ice expanding into air spaces.
What is the primary cause of thermal stress weathering?
Answer: Expansion and contraction of rock due to temperature changes.
Explanation: Thermal stress weathering is primarily caused by the expansion and contraction of rock materials in response to fluctuations in temperature.
What process leads to exfoliation or sheeting in deeply buried rocks exhumed to the Earth's surface?
Answer: Pressure release
Explanation: Exfoliation or sheeting in deeply buried rocks exhumed to the Earth's surface is caused by pressure release weathering, where the removal of overlying material allows the rock to expand.
In which environments is salt crystallization weathering most prevalent?
Answer: Arid climates with strong evaporation and along coastlines
Explanation: Salt crystallization weathering is most prevalent in arid climates characterized by strong evaporation and along coastlines, where saline solutions are abundant.
Chemical weathering converts stable primary minerals into less stable secondary minerals, making them more susceptible to further breakdown.
Answer: False
Explanation: Chemical weathering converts unstable primary minerals into more stable secondary minerals, which are more in equilibrium with Earth's surface conditions.
Mountain block uplift inhibits chemical weathering by burying rock strata deeper, away from atmospheric exposure.
Answer: False
Explanation: Mountain block uplift facilitates chemical weathering by exposing new rock strata to the atmosphere and moisture, rather than inhibiting it.
Dissolution is a chemical weathering process where a mineral completely dissolves in water without forming any new solid substances.
Answer: True
Explanation: Dissolution, or congruent dissolution, is a chemical weathering process where a mineral completely dissolves in water, forming dissolved solutes without leaving any new solid residues.
Carbonate dissolution is thermodynamically favored at high temperatures because warmer water can hold more dissolved carbon dioxide gas.
Answer: False
Explanation: Carbonate dissolution is thermodynamically favored at low temperatures because colder water can hold more dissolved carbon dioxide gas, leading to the formation of more carbonic acid.
Acid rain, formed from atmospheric pollutants, significantly accelerates solution weathering of exposed rocks due to increased acidity.
Answer: True
Explanation: Acid rain, resulting from atmospheric pollutants, lowers the pH of rainwater and produces stronger acids, which significantly accelerates the solution weathering of exposed rocks.
Hydrolysis is a form of chemical weathering where a mineral completely dissolves, similar to simple dissolution, but at a slower rate.
Answer: False
Explanation: Hydrolysis, or incongruent dissolution, differs from simple dissolution in that only a portion of the mineral dissolves, while the remaining part is transformed into a new solid material, such as a clay mineral.
During acid hydrolysis, minerals with stronger chemical bonds, like Si–O, weather more readily than those with weaker bonds.
Answer: False
Explanation: During acid hydrolysis, the weakest chemical bonds, such as K–O or Na–O, are attacked first, meaning minerals with weaker bonds weather more readily than those with stronger bonds like Si–O.
Oxidation in chemical weathering typically results in a characteristic reddish-brown coloration on affected rocks due to the formation of ferric iron oxides.
Answer: True
Explanation: Oxidation, particularly of ferrous iron to ferric iron oxides, imparts a characteristic reddish-brown coloration to affected rocks and minerals.
Mineral hydration involves the complete dissolving of a mineral as water molecules are rigidly attached to its atoms.
Answer: False
Explanation: Mineral hydration involves the rigid attachment of water molecules to a mineral's atoms without significant dissolving, unlike dissolution.
The hydration of a crystal surface is the crucial first step in hydrolysis, leading to the destabilization of the mineral.
Answer: True
Explanation: The hydration of a crystal surface is indeed the crucial initial step in hydrolysis, as it attracts water molecules and leads to the dissociation of water into H+ and OH- ions, thereby destabilizing the mineral surface.
What fundamental change does chemical weathering bring about in rocks?
Answer: It converts unstable primary minerals into more stable secondary minerals.
Explanation: Chemical weathering fundamentally changes rocks by converting unstable primary minerals into more stable secondary minerals that are in equilibrium with surface conditions.
How does mountain block uplift influence chemical weathering?
Answer: It exposes new rock strata to the atmosphere and moisture, facilitating weathering.
Explanation: Mountain block uplift influences chemical weathering by exposing fresh rock strata to the atmosphere and moisture, which facilitates significant chemical breakdown.
Which of the following is an example of dissolution in chemical weathering?
Answer: Rainwater dissolving quartz to form silicic acid.
Explanation: Dissolution is a process where a mineral completely dissolves without forming new solids, as exemplified by rainwater dissolving quartz to form silicic acid.
Why is carbonate dissolution particularly significant in glacial environments?
Answer: Because colder water can hold more dissolved carbon dioxide gas, forming more carbonic acid.
Explanation: Carbonate dissolution is significant in glacial environments because colder water can hold more dissolved carbon dioxide, leading to the formation of more carbonic acid, which enhances the dissolution of calcium carbonate.
How does hydrolysis (incongruent dissolution) differ from simple dissolution?
Answer: Hydrolysis transforms part of the mineral into a new solid, while simple dissolution dissolves the mineral completely.
Explanation: Hydrolysis (incongruent dissolution) differs from simple dissolution in that it transforms a portion of the mineral into a new solid, such as a clay mineral, whereas simple dissolution involves the complete dissolving of the mineral.
During acid hydrolysis, which type of chemical bonds within mineral crystals are attacked first?
Answer: The weakest bonds, such as K–O or Na–O.
Explanation: During acid hydrolysis, protons attack the weakest chemical bonds within mineral crystals first, such as K–O or Na–O bonds, rather than stronger Si–O bonds.
What is the visible effect of oxidation on rocks, particularly involving iron?
Answer: A characteristic reddish-brown coloration.
Explanation: Oxidation, especially involving iron, typically results in a characteristic reddish-brown coloration on affected rocks due to the formation of ferric iron oxides.
What is the crucial first step in the process of hydrolysis?
Answer: The hydration of the crystal surface.
Explanation: The crucial first step in hydrolysis is the hydration of the crystal surface, which attracts water molecules and initiates the destabilization of the mineral.
Lichens contribute to physical weathering by 'plucking' mineral grains and to chemical weathering by creating a humid microenvironment and internal chemical breakdown.
Answer: True
Explanation: Lichens contribute to physical weathering through 'plucking' mineral grains with their hyphae and to chemical weathering by creating a humid microenvironment and internal chemical breakdown processes akin to digestion.
The weathering of silicate minerals by carbonic acid consumes CO2 from the atmosphere, influencing global climate.
Answer: True
Explanation: The weathering of silicate minerals by carbonic acid consumes atmospheric CO2, thereby regulating its concentration and influencing global climate.
Soil microorganisms, such as lichens, have been shown to significantly decrease weathering rates of minerals compared to sterile conditions.
Answer: False
Explanation: Soil microorganisms, including lichens, significantly initiate or accelerate chemical weathering rates of minerals, rather than decreasing them.
Plant roots release chelating compounds and organic acids that help break down aluminum- and iron-containing compounds in soils.
Answer: True
Explanation: Plant roots release chelating compounds and organic acids, which, along with elevated CO2 levels, contribute to the breakdown of aluminum- and iron-containing compounds in soils.
Mycorrhizal fungi and bacterial communities primarily inhibit mineral weathering, thus preserving nutrient availability in soils.
Answer: False
Explanation: Mycorrhizal fungi and bacterial communities actively impact mineral stability and facilitate the release of inorganic nutrients, thereby promoting, rather than inhibiting, mineral weathering.
How do lichens contribute to physical weathering?
Answer: By using hyphae to pry mineral grains loose in a process called 'plucking'.
Explanation: Lichens contribute to physical weathering by using their hyphae to pry mineral grains loose from rock surfaces, a process known as 'plucking'.
What is the effect of silicate mineral weathering by carbonic acid on atmospheric CO2?
Answer: It consumes carbonic acid, thereby regulating atmospheric CO2 and influencing climate.
Explanation: The weathering of silicate minerals by carbonic acid consumes carbonic acid, which in turn regulates atmospheric CO2 levels and influences global climate.
How do soil microorganisms, such as lichens, generally impact chemical weathering rates?
Answer: They significantly initiate or accelerate chemical weathering.
Explanation: Soil microorganisms, including lichens, are known to significantly initiate or accelerate chemical weathering rates of minerals.
What compounds do plant roots release that contribute to biological weathering?
Answer: Chelating compounds, carbon dioxide, and other organic acids.
Explanation: Plant roots release chelating compounds, carbon dioxide, and various organic acids that contribute to the biological breakdown of minerals in soils.
Weathering of basaltic oceanic crust is a rapid process, leading to significant depletion of iron and magnesium.
Answer: False
Explanation: Weathering of basaltic oceanic crust is a relatively slow process, leading to enrichment in total and ferric iron and magnesium, not depletion.
In the weathering sequence of granitic rock, oligoclase and microcline are typically destroyed before hornblende and biotite.
Answer: False
Explanation: In the weathering sequence of granitic rock, hornblende is typically destroyed first, followed by biotite, and then oligoclase and microcline are broken down later.
During the weathering of granitic bedrock, the resulting soil becomes enriched in calcium, sodium, and ferrous iron compared to the original rock.
Answer: False
Explanation: During the weathering of granitic bedrock, the resulting soil becomes *depleted* in elements such as calcium, sodium, and ferrous iron compared to the original rock, while becoming enriched in aluminum, potassium, titanium, and ferric iron.
Basaltic rock weathers more easily than granitic rock due to its formation under higher temperatures and drier conditions, along with its fine grain size.
Answer: True
Explanation: Basaltic rock weathers more easily than granitic rock because it forms under higher temperatures and drier conditions, and its fine grain size and volcanic glass content contribute to its faster breakdown.
In tropical settings, basalt typically weathers directly to kaolinite, then to potassium-poor montmorillonite.
Answer: False
Explanation: In tropical settings, basalt typically weathers directly to potassium-poor montmorillonite, and then to kaolinite, not the other way around.
Soil formation generally requires millions of years, making paleosols rare in the geological record.
Answer: False
Explanation: Soil formation typically requires 100 to 1,000 years, a relatively brief geological period, and paleosols are found in geological formations as old as the Archean Eon, indicating they are not rare.
Paleosols are recognized by a sharp lower boundary, a low clay content, and well-sorted sedimentary structures.
Answer: False
Explanation: Paleosols are recognized by a gradational lower boundary, a high clay content, poor sorting with few sedimentary structures, and other specific indicators, not the characteristics listed.
The chemical index of alteration (CIA) ranges from 47 for unweathered upper crust rock to 100 for fully weathered material.
Answer: True
Explanation: The Chemical Index of Alteration (CIA) is a quantitative measure of soil weathering, ranging from 47 for unweathered upper crust rock to 100 for fully weathered material.
What is the approximate time scale for soil formation?
Answer: 100 to 1,000 years
Explanation: Soil formation generally requires a relatively brief geological period, typically between 100 and 1,000 years.
Which of the following is an indicator used by geologists to recognize paleosols in the geological record?
Answer: A gradational lower boundary and a sharp upper boundary.
Explanation: Geologists recognize paleosols by indicators such as a gradational lower boundary and a sharp upper boundary, along with high clay content and poor sorting.
What does a Chemical Index of Alteration (CIA) value of 100 indicate?
Answer: Fully weathered material.
Explanation: A Chemical Index of Alteration (CIA) value of 100 indicates fully weathered material, representing the maximum degree of alteration.
Buildings and monuments are susceptible to weathering, and this deterioration is significantly accelerated by acid rain.
Answer: True
Explanation: Buildings and monuments are vulnerable to the same weathering agents as natural rocks, and their deterioration is markedly accelerated by the presence of acid rain.
Using concrete mixes with increased water content is a design strategy to minimize the effects of freeze-thaw cycles in buildings.
Answer: False
Explanation: To minimize the effects of freeze-thaw cycles in buildings, design strategies include selecting concrete mixes with *reduced* water content, not increased.
Wood, paint, and plastic are primarily weathered by hydrolysis and mineral-relevant processes, with UV radiation having minimal impact.
Answer: False
Explanation: Wood, paint, and plastics are significantly weathered by ultraviolet (UV) radiation from sunlight, which triggers photochemical reactions, in addition to other processes.
Concrete damaged by acid rain illustrates that artificial materials are immune to chemical weathering processes.
Answer: False
Explanation: Concrete damaged by acid rain illustrates that artificial materials are highly susceptible to chemical weathering processes, particularly from environmental pollutants.
Salt weathering on building stone in Gozo, Malta, demonstrates the impact of salt crystallization in coastal environments.
Answer: True
Explanation: Salt weathering on building stone in Gozo, Malta, demonstrates the significant impact of salt crystallization on structures in coastal environments where saline solutions and high evaporation are prevalent.
What is a significant weathering agent for wood, paint, and plastics?
Answer: Ultraviolet (UV) radiation from sunlight
Explanation: Ultraviolet (UV) radiation from sunlight is a significant weathering agent for wood, paint, and plastics, triggering photochemical reactions that degrade their surfaces.
What does concrete damaged by acid rain illustrate about artificial materials?
Answer: Artificial materials are highly susceptible to chemical weathering, especially from pollutants.
Explanation: Concrete damaged by acid rain illustrates that artificial materials are highly susceptible to chemical weathering, particularly when exposed to environmental pollutants that increase the acidity of precipitation.
What does the image of salt weathering on building stone in Gozo, Malta, demonstrate?
Answer: The significant impact of salt crystallization on structures in coastal environments.
Explanation: The image of salt weathering on building stone in Gozo, Malta, demonstrates the significant impact of salt crystallization on structures in coastal environments where saline solutions are prevalent.
The formation of natural arches, as seen in Jebel Kharaz, Jordan, is an example of differential weathering combined with erosion.
Answer: True
Explanation: Natural arches, such as those in Jebel Kharaz, Jordan, are formed through the combined action of differential weathering, where some parts of the rock weather more easily, and erosion, which removes the weathered material.
Fractured rocks in cold climates, like Abisko, Sweden, suggest that physical weathering mechanisms can exploit existing geological joints.
Answer: True
Explanation: Fractured rocks in cold climates, such as Abisko, Sweden, demonstrate that physical weathering mechanisms like frost weathering or thermal stress can effectively exploit and enlarge existing geological joints.
Exfoliated granite sheets, as seen in Texas, are primarily formed by chemical dissolution of the rock's outer layers.
Answer: False
Explanation: Exfoliated granite sheets are primarily formed by pressure release weathering (unloading), where outer layers of rock peel away due to the reduction of confining pressure, not chemical dissolution.
Tafoni, cavernous rock structures at Salt Point State Park, California, are likely formed by frost wedging in coastal environments.
Answer: False
Explanation: Tafoni, cavernous rock structures, are likely formed by salt crystallization (salt weathering) in coastal environments, not primarily by frost wedging.
Limestone core samples from the Democratic Republic of Congo show that chemical weathering is highest at greater depths and uniform throughout the rock.
Answer: False
Explanation: Limestone core samples reveal that chemical weathering is very high at shallow depths and very low at greater depths, indicating it is not uniform throughout the rock.
The transformation of olivine to iddingsite within a mantle xenolith exemplifies the chemical weathering process of oxidation.
Answer: False
Explanation: The transformation of olivine to iddingsite within a mantle xenolith exemplifies the chemical weathering process of hydrolysis, not oxidation.
The dissolution of a pyrite cube, leaving gold particles behind, demonstrates the chemical weathering process of oxidation.
Answer: True
Explanation: The dissolution of a pyrite cube, leaving gold particles, demonstrates oxidation, where sulfide minerals break down, concentrating resistant materials like gold.
Biological weathering of basalt by lichen, as seen in La Palma, highlights the significant role of organisms in rock breakdown.
Answer: True
Explanation: The biological weathering of basalt by lichen in La Palma highlights the significant role that living organisms play in the breakdown of rock surfaces.
What does the image of a natural arch in Jebel Kharaz, Jordan, illustrate about weathering and erosion?
Answer: That differential weathering combined with erosion sculpts distinctive landforms.
Explanation: The natural arch in Jebel Kharaz, Jordan, illustrates how the combined action of differential weathering and erosion sculpts distinctive landforms.
What geological process is depicted by exfoliated granite sheets in Texas?
Answer: Pressure release weathering (exfoliation)
Explanation: Exfoliated granite sheets in Texas depict pressure release weathering, also known as exfoliation, where outer layers of rock peel away due to reduced confining pressure.
What type of weathering is likely responsible for the formation of tafoni, cavernous rock structures, at Salt Point State Park, California?
Answer: Salt crystallization (salt weathering)
Explanation: Tafoni, cavernous rock structures, are likely formed by salt crystallization (salt weathering), particularly in coastal environments where saline solutions are prevalent.
What do limestone core samples from the Democratic Republic of Congo reveal about chemical weathering with depth?
Answer: Chemical weathering is very high at shallow depths and very low at greater depths.
Explanation: Limestone core samples from the Democratic Republic of Congo reveal that chemical weathering is very high at shallow depths and significantly diminishes at greater depths.
The transformation of olivine to iddingsite within a mantle xenolith is an example of which chemical weathering process?
Answer: Hydrolysis
Explanation: The transformation of olivine to iddingsite within a mantle xenolith is an example of hydrolysis, a chemical weathering process where a primary mineral is altered into a new secondary mineral.
What does the image of a pyrite cube dissolved from host rock, leaving gold particles, demonstrate?
Answer: Oxidation, leading to the breakdown of sulfide minerals and concentration of resistant materials.
Explanation: The image demonstrates oxidation, a chemical weathering process where sulfide minerals like pyrite break down, leading to the concentration of resistant materials such as gold.
What is the visual characteristic of oxidized pyrite cubes?
Answer: A reddish-brown coloration on the surface.
Explanation: Oxidized pyrite cubes typically exhibit a reddish-brown coloration on their surface, characteristic of iron oxidation.
What does the image of biological weathering of basalt by lichen in La Palma highlight?
Answer: The significant role that living organisms play in rock breakdown.
Explanation: The image of biological weathering of basalt by lichen in La Palma highlights the substantial role that living organisms play in the breakdown of rock surfaces through both physical and chemical processes.
What does the image of a Permian sandstone wall in Sedona, Arizona, weathered into a small alcove, demonstrate?
Answer: The long-term and sculptural effects of weathering processes on rock formations.
Explanation: The image of a Permian sandstone wall in Sedona, Arizona, weathered into a small alcove, demonstrates the long-term and sculptural effects of weathering processes in shaping rock formations over geological timescales.