Examkin

Physical Geography

261 questions

All types261Multiple choice127Numeric28Matching61Ordering45
Question 141Question →

Carbonation is a primary chemical weathering process that degrades limestone landscapes. What is the correct chronological sequence of steps involved in carbonation, from the initial formation of acidic rainwater to the final removal of dissolved rock materials?

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence begins with carbon dioxide dissolving in rainwater to form carbonic acid, followed by acidic rainwater contacting limestone, chemical reaction forming soluble calcium bicarbonate, and finally the removal of dissolved calcium bicarbonate in solution by water.
Carbonation begins when carbon dioxide dissolves in rainwater to form weak carbonic acid. When this acidic rainwater contacts limestone, it converts insoluble calcium carbonate into soluble calcium bicarbonate, which is subsequently washed away in solution by moving water.

Step-by-Step Solution

1
Identify the initial chemical reaction in the atmosphere.
Rainwater absorbs carbon dioxide to form weak carbonic acid (CO2+H2O→H2CO3CO_2 + H_2O \rightarrow H_2CO_3).
Chemical weathering cannot begin until the chemical weathering agent is synthesized in precipitation.
2
Trace the movement of the acid solution onto rock surfaces.
Acidic rainwater flows along limestone joints and bedding planes.
The acid must infiltrate the rock structure to react with calcium carbonate minerals.
3
Determine the chemical conversion of the rock mineral.
Carbonic acid reacts with calcium carbonate to form soluble calcium bicarbonate (CaCO3+H2CO3→Ca(HCO3)2CaCO_3 + H_2CO_3 \rightarrow Ca(HCO_3)_2).
Insoluble rock material is converted into a dissolved compound.
4
Identify the final removal of dissolved material.
Groundwater washes away dissolved calcium bicarbonate in solution.
Continuous removal of soluble minerals enlarges joints, producing caves and karst features.

Key Concept

Chemical weathering of limestone via carbonation
Estimated Time:1m 0s
Question 142Question →

Match each weathering or mass wasting process on the left with its primary defining mechanism or environmental manifestation on the right.

Click a left item, then click its matching right item

Items

Hydrolysis
Carbonation
Frost Shattering
Solifluction

Matches

Show answer & explanation

Answer

Hydrolysis matches the chemical decomposition of silicate minerals into kaolinite clay; Carbonation matches the dissolution of calcium carbonate into soluble calcium bicarbonate by carbonic acid; Frost Shattering matches the mechanical disintegration of jointed rock by freezing water expansion; Solifluction matches the slow downslope flow of saturated soil over permafrost.
Each process matches its exact physical, chemical, or geomorphic behavior. Hydrolysis chemically converts silicate minerals like feldspar to kaolinite clay. Carbonation dissolves calcium carbonate into soluble bicarbonate using carbonic acid. Frost shattering mechanically disintegrates rock via the volumetric expansion of freezing water in joint spaces. Solifluction is the periglacial mass movement of waterlogged soil flowing over impermeable permafrost under gravity.

Step-by-Step Solution

1
Differentiate between in-situ chemical weathering, in-situ mechanical weathering, and downslope mass wasting processes.
Hydrolysis and Carbonation are identified as chemical weathering; Frost Shattering is identified as mechanical weathering; Solifluction is identified as mass wasting.
Chemical weathering alters mineral composition, mechanical weathering physically breaks rock without chemical change, and mass wasting involves movement of material downslope under gravity.
2
Analyze the chemical reactions for Hydrolysis and Carbonation to match their respective definitions.
Hydrolysis specifically targets silicate minerals like feldspar producing clay minerals (kaolinite), while Carbonation acts on carbonate rocks (limestone) using carbonic acid.
The reaction mechanism of hydrogen ions replacing cations distinguishes hydrolysis from the acid-dissolution dynamics of carbonation.
3
Evaluate the mechanical wedging mechanism vs. the mass movement process.
Frost Shattering relies on the 9% volume expansion of ice wedging in rock joints, whereas Solifluction requires saturated topsoil sliding over permafrost under gravity.
Frost shattering operates in-situ on rock outcrops, while solifluction represents flow transport of regolith down a slope.

Key Concept

Classification and underlying mechanics of physical weathering, chemical weathering, and mass wasting processes.
Estimated Time:1m 30s
Question 143Question →

Which landform is produced in the upper course of a river when swirling eddy currents carrying pebbles grind cylindrical depressions into the riverbed bedrock?

Show answer & explanation

Answer: Potholes

Answer

Potholes are circular bedrock depressions created by the swirling action of river load (pebbles and gravel) driven by eddy currents in the upper course.
Potholes are smooth, cylindrical depressions carved into solid bedrock along a river channel. They form primarily in steep upper courses where swift-flowing water creates eddies that whirl pebbles around, drilling deep holes into bedrock depressions.

Step-by-Step Solution

1
Identify the process described in the stem.
The process described is pothole drilling (swirling river currents holding stone tools that erode bedrock).
Corrasion (abrasion) combined with eddy currents in swift-flowing water drills circular holes into irregularities in a stream bed.
2
Associate the process with its corresponding landform and course stage.
Potholes are distinctive erosional features of the upper (torrential) stage of a river.
High stream velocity and turbulent flow in steep upper courses provide the energy required for pebbles to carve circular hollows.

Key Concept

Fluvial Erosional Processes in the Upper Course
Question 144Question →

In arid regions, wind action causes severe erosion through different mechanics. Which landform is created when wind abrasion selectively undercuts the base of a rock outcrop more rapidly than its top due to sand particles being carried close to the ground?

Show answer & explanation

Answer: Mushroom rock

Answer

Mushroom rock (also known as a pedestal rock)
Wind abrasion in deserts is most effective close to the ground where wind-borne sand particles are concentrated. When an isolated rock mass is exposed to this sandblasting action, the lower portion erodes significantly faster than the upper part, creating a distinctive mushroom rock (pedestal rock).

Step-by-Step Solution

1
Identify the primary agent and mechanism described in the question
The agent is wind (aeolian process) using wind abrasion (sandblasting action near ground level).
Wind action carries the heaviest abrasive tools (sand grains) close to the surface, typically within 1 to 1.5 meters above the ground.
2
Analyze the structural outcome of ground-level undercutting on an isolated rock
The base of the rock undergoes maximum erosion while the top remains wider and less eroded.
Differential erosion leaves a narrow stalk supporting a wider cap rock, forming a pedestal or mushroom shape.

Key Concept

Aeolian Abrasion and Landform Development
Question 145Question →

During stream piracy, an aggressive river tributary undergoes active headward erosion, breaching a watershed divide and intercepting the flow of a neighboring stream. Which landform is created in the abandoned valley immediately downstream of the elbow of capture?

Show answer & explanation

Answer: Wind gap

Answer

A wind gap is formed in the abandoned valley immediately downstream of the elbow of capture during river piracy.
When a river captures the upper waters of an adjacent stream, the valley downstream from the elbow of capture is deprived of its main water source. The dry gap or pass cut through the ridge where the original river used to flow is known as a wind gap.

Step-by-Step Solution

1
Analyze the geomorphic process described in the stem.
The process is stream piracy (river capture), where active headward erosion enables one stream to breach a watershed divide and divert another stream's flow.
Understanding stream piracy features requires identifying what happens at and downstream of the interception point (elbow of capture).
2
Identify the features associated with stream piracy.
The interception site is the elbow of capture; the diverted upper stream becomes the pirate stream; the stream below the elbow loses its headwaters and becomes a misfit stream; and the abandoned, dry valley pass downstream of the elbow forms a wind gap.
Landform classification in fluvial geomorphology relies on linking specific river processes to their resultant morphological features.

Key Concept

Stream Piracy (River Capture) and Associated Fluvial Landforms
Estimated Time:1m 15s
Question 146Question →

What is the correct sequential order of stages in the evolution of a natural limestone bridge, from initial subterranean dissolution to the final exposure of the arch?

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence begins with percolating carbonated water dissolving limestone joints, followed by the enlargement of underground caverns, localized roof collapse forming karst windows, and finally progressive collapse leaving an isolated roof section as a natural bridge.
Karst landscape evolution follows a strict chronological sequence: initial solution along limestone joint planes by acidulated groundwater creates conduits; continuous subterranean water action enlarges these conduits into vast caverns; progressive ceiling dissolution leads to localized roof failure forming karst windows; and extensive collapse of surrounding roof sections leaves an isolated intact segment spanning the valley as a natural bridge.

Step-by-Step Solution

1
Identify the primary process initiating subterranean karst landform development.
Rainwater enriched with carbon dioxide percolates through limestone joints and bedding planes.
Carbonation is the essential chemical weathering process that initiates underground solution in soluble limestone bedrock.
2
Trace the expansion of subsurface drainage networks into void spaces.
Dissolved joint lines are widened into subterranean stream channels and cavern systems.
Sustained groundwater flow and chemical solution widen fissures into massive cavern chambers over time.
3
Determine the initial structural collapse feature resulting from roof instability.
Localized cavern roof collapse creates karst windows exposing subterranean rivers to the surface.
As cavern chambers enlarge, structural support is lost, causing roof failure in weaker sections.
4
Identify the final residual landform exposed after widespread roof collapse.
A surviving segment of uncollapsed cavern roof remains standing across the valley, forming a natural arch or bridge.
A natural limestone bridge represents a remnant cavern roof feature preserved after surrounding cavern roofs have completely collapsed.

Key Concept

Subterranean Karst Solution and Cavern Roof Evolution
Question 147Question →

A meteorological vessel measures its local solar time to be 3:20 p.m.3:20\text{ p.m.} when Greenwich Mean Time (0∘0^\circ) is 11:00 a.m.11:00\text{ a.m.} on the same day. What is the longitude of the vessel in degrees East?

Show answer & explanation

Answer: 65

Answer

The longitude of the vessel is 65∘E65^\circ\text{E}.
The time difference between 3:20 p.m.3:20\text{ p.m.} and 11:00 a.m.11:00\text{ a.m.} is 4 hours and 20 minutes (260 minutes260\text{ minutes}). Since the Earth rotates 1∘1^\circ every 4 minutes, 260 minutes÷4=65∘260\text{ minutes} \div 4 = 65^\circ. Because the vessel's local solar time is ahead of Greenwich Mean Time, the vessel is located east of the Prime Meridian, yielding 65∘E65^\circ\text{E}.

Step-by-Step Solution

1
Calculate time difference
4 hours 20 minutes (260 minutes)
Subtract GMT (11:00 a.m.) from local solar time (3:20 p.m.).
2
Convert time difference to longitude degrees
65 degrees
Divide total time difference in minutes (260) by 4 minutes per degree of Earth's rotation.
3
Determine longitudinal hemisphere
East
Local time is ahead of GMT, which indicates a position to the east of the Prime Meridian.

Key Concept

Calculation of longitude from local time and Greenwich Mean Time (GMT) using Earth's rotation rate
Question 148Question →

Match each seismic discontinuity of the Earth's interior in Column I with its defining structural interface or wave behavior in Column II. Which alignment correctly matches each discontinuity to its boundary feature?

Click a left item, then click its matching right item

Items

Conrad Discontinuity
Mohorovičić Discontinuity
Gutenberg Discontinuity
Lehmann Discontinuity

Matches

Show answer & explanation

Answer

Conrad Discontinuity corresponds to the intra-crustal boundary between SIAL and SIMA; Mohorovičić Discontinuity corresponds to the boundary between the crust and mantle; Gutenberg Discontinuity corresponds to the core-mantle boundary where S-waves drop to zero; Lehmann Discontinuity corresponds to the boundary between the liquid outer core and solid inner core.
Each discontinuity represents a specific geophysical transition within the Earth's interior. The Conrad discontinuity is intra-crustal (SIAL/SIMA), the Mohorovičić discontinuity is crust-mantle, the Gutenberg discontinuity is mantle-outer core (where liquid stops S-waves), and the Lehmann discontinuity is outer core-inner core.

Step-by-Step Solution

1
Identify intra-crustal zoning features
The Conrad discontinuity lies within the crust, separating the granitic upper crust (SIALSIAL) from the basaltic lower crust (SIMASIMA).
It represents a density contrast within continental crustal material.
2
Identify the crust-mantle boundary
The Mohorovičić discontinuity separates continental and oceanic crust from the denser peridotite mantle below.
Seismic wave velocities increase markedly across this compositional boundary.
3
Identify the mantle-core transition
The Gutenberg discontinuity occurs at 2,900 km2,900\text{ km} depth, marking the change from the solid mantle to the liquid outer core where S-waves cannot propagate.
Shear waves cannot pass through liquid media.
4
Identify the inner-outer core boundary
The Lehmann discontinuity separates the liquid iron-nickel outer core from the solid inner core at a depth of roughly 5,150 km5,150\text{ km}.
Higher pressure at the center forces iron and nickel into a solid metallic crystal structure despite high temperatures.

Key Concept

Internal Structure of the Earth and Seismic Discontinuities
Question 149Question →

Mass wasting processes exhibit varying rates of downslope movement based on slope angle, moisture saturation, and particle mechanics. Arrange the following mass wasting processes in sequence according to their typical velocity of movement, starting from the slowest process to the fastest process.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence from slowest to fastest rate of movement is: Soil creep driven by freeze-thaw cycles, followed by Solifluction over permafrost, then Debris flow surging down a channel, and finally Rock avalanche riding on air cushion.
Mass wasting processes are categorized along a velocity spectrum. Soil creep operates imperceptibly (< 1 cm/year) as individual soil particles shift downslope during expansion-contraction cycles. Solifluction is slightly faster (cm to m/year) as saturated topsoil flows over frozen subsoil. Debris flows move rapidly (m/s) as liquid-saturated materials surge through steep channels. Rock avalanches are catastrophic and move fastest (> 50 m/s) because air trapped beneath the plunging rock mass drastically reduces friction.

Step-by-Step Solution

1
Identify the slowest mass wasting process governed by microscopic particle shifting.
Soil creep operates imperceptibly (rates < 1 cm/year) due to alternating freeze-thaw or wet-dry particle expansion and contraction.
It involves dry-to-moist diffuse mantle displacement across low-to-moderate gradients.
2
Identify the slow viscous flow process restricted to saturated surface layers.
Solifluction moves at rates of several centimeters to meters per year as water-logged soil flows over impermeable permafrost or clay hardpans.
High pore-water pressure reduces shear strength, but movement remains constrained by ground thermal conditions.
3
Identify the rapid fluid-like channelized flow mass movement.
Debris flows travel rapidly down steep channels at velocities from 1 m/s to over 10 m/s following intense precipitation events.
Liquefaction and fluid displacement transform the material into a fast-moving slurry.
4
Identify the extremely rapid high-energy slope collapse event.
Rock avalanches move at extreme velocities exceeding 50 to 100 meters per second.
Catastrophic rock slope failure generates air entrapment beneath the sliding debris mass, drastically eliminating friction.

Key Concept

Classification of mass wasting processes based on movement mechanics and velocity spectrum
Question 150Question →

Arrange the following structural layers of the Earth in sequence from the outermost surface layer down to the Earth's center.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct order from the Earth's surface descending to its center is Sial, Sima, Asthenosphere, Lower Mantle, and Barysphere.
The structural layers of the Earth arranged from the outermost surface to the center follow a progression based on increasing density and depth: Sial (upper continental crust), Sima (lower crust/oceanic basin floor), Asthenosphere (ductile upper mantle zone), Lower Mantle (solid silicate interior), and Barysphere (innermost metallic core).

Step-by-Step Solution

1
Identify the outermost crustal layers based on composition and density.
Sial forms the upper continental crust, lying directly above the denser Sima layer.
Sial has a lower average density (2.7 g/cm32.7\text{ g/cm}^3) than Sima (3.0 g/cm33.0\text{ g/cm}^3), allowing it to float on top of the sima layer.
2
Determine the position of mantle layers relative to the crust.
The semi-fluid Asthenosphere lies in the upper mantle beneath the crust, followed by the rigid Lower Mantle below it.
The lithosphere (crust and uppermost solid mantle) rests upon the ductile asthenosphere, which transitions into the deeper, solid lower mantle.
3
Locate the central core region of the Earth.
The Barysphere occupies the innermost portion of the Earth.
The metallic core (Barysphere) possesses the highest density (10.0–13.0 g/cm310.0\text{--}13.0\text{ g/cm}^3) and occupies the central interior of the planet.

Key Concept

Concentric internal layering of the Earth from surface to center
Question 151Question →

Arrange the stages of barchan dune formation in an arid environment in sequential order from initial sand accumulation to the fully developed landform.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence begins with sand encountering an obstacle and depositing, followed by the formation of a sand mound with a leeward slip face, the extension of lateral horns downwind by wind eddies, and finally the migration of a mature crescent-shaped barchan dune.
The correct sequence follows the physical progression of aeolian deposition: wind-blown sand first accumulates around an obstacle, forms an asymmetrical sand mound with a leeward slip face, develops two downwind-pointing horns as marginal sand moves faster than the center, and ultimately becomes a mobile crescent barchan dune.

Step-by-Step Solution

1
Identify the initial trigger for wind deposition.
Sand carried by saltation is trapped by an obstacle on the desert surface.
Aeolian deposition requires a physical barrier or reduction in wind energy.
2
Determine the initial structural dune development.
Sand accumulates into an asymmetrical mound with a gentle windward side and steep leeward slip face.
Sand accumulates on the windward slope and avalanches down the leeward side when it exceeds the angle of repose.
3
Trace the development of characteristic lateral features.
Lighter sand loads at the lateral margins move faster downwind, forming two pointed horns.
Eddy currents and lower resistance at the edges push the sides forward faster than the thick central core.
4
Identify the final landform state.
A fully formed crescent-shaped barchan dune migrates in the direction of the prevailing wind.
Ongoing wind action continually recycles sand over the crest, causing the entire dune to advance.

Key Concept

Barchan Dune Formation and Aeolian Deposition Processes
Question 152Question →

Which of the following landforms is formed in the upper course of a river primarily by active vertical erosion?

Show answer & explanation

Answer: V-shaped valley

Answer

V-shaped valley
In the upper course of a river, steep slopes cause rapid streamflow that drives energetic vertical erosion. As the river deepens its bed, weathering and mass wasting loosen materials along the sides, producing a steep-sided V-shaped valley profile.

Step-by-Step Solution

1
Identify the dominant river process and course stage
The upper course stage features steep gradients, fast flow velocity, and downward channel incision (vertical erosion).
River kinetic energy in the upper course is mainly directed toward deepening the valley bed.
2
Determine the resulting morphological feature
Deepening of the stream bed combined with weathering of upper valley sides produces a narrow V-shaped valley.
Vertical hydraulic action and corrasion cut downward while mass movement slumps the valley slopes inward.

Key Concept

Upper river course erosion and landform development
Question 153Question →

In Karst geomorphology, subterranean dissolution of limestone leads to distinct underground and surface landforms. Arrange the following stages of subterranean cavern and collapse feature evolution in their correct chronological order from earliest to latest.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence begins with carbonated water percolating through joints, followed by fracture widening into conduit networks, horizontal cavern development at the water table, speleothem deposition and column growth, and culminates in roof collapse forming karst windows.
The sequence correctly reflects the geomorphological progression from microscopic chemical infiltration of carbonated water into limestone joints, through sub-surface conduit and cavern chamber dissolution at the water table, followed by speleothem dripstone growth inside aerated caverns, ending with cavern roof breakdown resulting in karst windows.

Step-by-Step Solution

1
Identify the initial chemical weathering action.
Rainwater absorbing carbon dioxide forms weak carbonic acid that infiltrates limestone bedding planes and vertical joints.
Chemical dissolution cannot occur underground without initial acidic water entry into rock fractures.
2
Trace the subterranean conduit formation.
Acidic groundwater widens joints and bedding planes into vertical shafts and narrow conduit networks.
Initial dissolution follows structural weaknesses before forming large subterranean chambers.
3
Determine cavern chamber creation at the water table.
Lateral water movement at the phreatic boundary dissolves massive subterranean chambers.
Horizontal flow at the water table concentrates dissolution laterally rather than vertically.
4
Sequence the secondary depositional speleothem features.
Degassing of carbon dioxide in subterranean air spaces deposits calcite stalactites, stalagmites, and coalescing columns.
Depositional dripstone features require air-filled cavern vaults created during water table lowering or vadose flow.
5
Identify the final structural collapse landform stage.
Cavern roof collapse exposes the subterranean river flow as a karst window or collapsed sinkhole gorge.
Extreme underground enlargement coupled with roof thinning causes mechanical instability and ceiling breakdown.

Key Concept

Subterranean cavern evolution and cave roof collapse dynamics in karst topography
Estimated Time:2m 0s
Question 154Question →

Geophysical and structural evaluations of the Earth distinguish between compositional layers (crust, mantle, core) and mechanical zones (lithosphere, asthenosphere). Which of the following statements accurately characterizes the compositional and structural relationships between the continental crust, oceanic crust, and the underlying mantle zones?

Show answer & explanation

Answer: The continental crust (sial) is predominantly granitic and lighter than the continuous basaltic layer (sima), which forms the oceanic floor and rests above the plastic asthenosphere.

Answer

The continental crust (sial) is predominantly granitic and lighter than the continuous basaltic layer (sima), which forms the oceanic floor and rests above the plastic asthenosphere.
The continental crust (sial) is rich in silica and aluminium, making it less dense and predominantly granitic. It sits upon the denser, continuous basaltic layer rich in silica and magnesium (sima), which underlies ocean basins and overlies the partially molten, ductile asthenosphere in the upper mantle.

Step-by-Step Solution

1
Analyze Earth's crustal composition
Sial (silica-aluminium, granitic) forms continental blocks with lower density (~2.7 g/cm³), while Sima (silica-magnesium, basaltic) forms oceanic crust and underlying basement with higher density (~3.0 g/cm³).
Establishing correct density and composition relationships between sial and sima.
2
Evaluate mantle mechanical zone relationship
The rigid lithosphere (crust + upper mantle) floats and moves over the ductile, semi-fluid asthenosphere.
Connecting compositional layers to mechanical behavior.
3
Eliminate options containing geological process misconceptions
Distractors confuse surface weathering with mass movement or igneous/metamorphic rock formation with sedimentary processes.
Validating the unique accuracy of the correct option.

Key Concept

Earth's Internal Structure (Sial, Sima, Lithosphere, and Asthenosphere)
Estimated Time:1m 30s
Question 155Question →

Block disintegration is a mechanical weathering process prevalent in arid desert regions. What is the correct chronological sequence of steps in the breakdown of rocks by block disintegration?

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence begins with daytime thermal expansion of the rock, followed by nighttime thermal contraction, leading to repeated stress along joints, and culminating in the rock fracturing into angular blocks.
Block disintegration occurs due to large diurnal temperature variations in arid regions. Heating during the day leads to expansion, while cooling at night leads to contraction. Over time, these recurring cycles generate stresses along joint lines, eventually causing the rock to fragment into large rectangular or angular blocks in-situ.

Step-by-Step Solution

1
Identify the initial thermal trigger in desert weathering.
Intense solar radiation during the day causes the rock to absorb heat and expand.
Rocks are poor conductors of heat, so daytime heating affects the outer layers first, causing localized expansion.
2
Determine the atmospheric response during the night.
Clear skies in arid regions lead to rapid nocturnal cooling, causing the expanded rock to contract.
Desert environments experience high diurnal temperature ranges.
3
Analyze the long-term mechanical impact of these temperature fluctuations.
Alternating expansion and contraction create differential stress along joint planes.
Repeated mechanical stress weakens the structural integrity of the rock along existing joints.
4
Identify the final physical outcome of the process.
The rock mass completely separates into distinct angular blocks.
When stress exceeds the strength of the rock, complete disintegration occurs along the joints.

Key Concept

Thermal expansion and contraction (block disintegration) in physical weathering
Question 156Question →

Coastal processes shape coastal environments through marine erosion, transportation, and deposition. Which of the following features is created primarily by coastal deposition?

Show answer & explanation

Answer: Beach

Answer

Beach
Beaches are temporary or permanent accumulations of sediment (sand, gravel, or pebbles) deposited along the coast by constructive waves where wave energy is low.

Step-by-Step Solution

1
Identify the primary agent of coastal deposition
Constructive waves build up landforms by depositing sediments like sand and pebbles along the shoreline.
Coastal landforms are classified into erosional features (like sea cliffs, arches, stacks) and depositional features (like beaches, spits, bars).
2
Evaluate the landform options against coastal deposition
Beaches consist of accumulated sand and shingle deposited by swash-dominated wave action.
Distinguish coastal marine landforms from river landforms, slope weathering features, and rock metamorphic structures.

Key Concept

Coastal Depositional Landforms
Question 157Question →

Pair each rock listed on the left with its corresponding origin, texture, and practical utilization on the right.

Click a left item, then click its matching right item

Items

Rock Salt
Gabbro
Slate
Chalk

Matches

Show answer & explanation

Answer

Rock Salt matches the chemical evaporite used in industrial chemical synthesis; Gabbro matches the coarse-grained intrusive igneous rock used as heavy aggregate; Slate matches the fine-grained foliated metamorphic rock used for roofing material; Chalk matches the soft, porous organic sedimentary rock used in cement manufacturing.
Each rock is matched according to its fundamental mode of origin and practical industrial importance: Rock Salt is a chemical evaporite; Gabbro is an intrusive mafic igneous rock; Slate is a foliated metamorphic rock derived from shale; Chalk is an organic sedimentary rock composed of microscopic shells.

Step-by-Step Solution

1
Determine the genesis and industrial utility of Rock Salt.
Rock salt is a chemical sedimentary rock created by water evaporation, utilized primarily in chemical processes and food preservation.
Evaporites form when mineral-saturated solutions evaporate in dry environments.
2
Determine the genesis and industrial utility of Gabbro.
Gabbro is a plutonic igneous rock with large crystals, widely extracted for crushed stone and heavy construction projects.
Slow cooling of mafic magma underground leads to a coarse crystalline texture.
3
Determine the genesis and industrial utility of Slate.
Slate originates from clay or shale subjected to low-grade metamorphic compression, creating planar cleavage useful for roofing sheets.
Regional pressure rearranges clay minerals perpendicular to stress directions.
4
Determine the genesis and industrial utility of Chalk.
Chalk is a variety of limestone composed of microscopic calcium carbonate shells, extensively quarried for manufacturing cement.
Organic accumulation of calcareous microorganisms creates soft, porous limestone beds.

Key Concept

Classification, textures, formation processes, and economic applications of major rock types.
Question 158Question →

In alpine and high-latitude environments, mechanical weathering continuously alters exposed rock slopes through freeze-thaw action. Arrange the following sequential stages of frost wedging in the correct chronological order from initial water accumulation to final downslope accumulation.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct chronological sequence of frost wedging starts with meltwater infiltration into rock fractures, followed by freezing as temperatures drop, volumetric expansion exerting outward pressure on joint walls, and culminating in repeated freeze-thaw cycles splitting the rock into scree at the mountain base.
Frost wedging follows a precise physical progression: liquid water infiltrates open joint lines, freezes when temperatures fall below 0°C, expands by ~9% in volume to exert immense pressure on surrounding rock walls, and ultimately fractures the rock completely over repeated cycles to form scree deposits at the base.

Step-by-Step Solution

1
Identify the initial process leading to frost wedging.
Liquid meltwater must first enter pre-existing cracks and joints within exposed rock surfaces during daytime or warmer seasons.
Without liquid water infiltration into rock voids, freeze-thaw action cannot initiate.
2
Determine the thermal change leading to phase transition.
Temperatures drop below the freezing threshold (0°C), converting the trapped water into ice.
Cooling is necessary for the phase change from liquid water to solid ice within the confined space.
3
Analyze the mechanical stress generated by the phase change.
Water expands by about 9% upon freezing, generating heavy outward lateral pressure against internal rock walls.
The volumetric expansion of ice directly generates mechanical stress within rock joints.
4
Identify the cumulative landform result of repeated stress.
Frequent oscillation around freezing point breaks jointed blocks apart, causing them to fall downslope to form talus/scree slopes.
Repeated stress cycles eventually overcome rock cohesion, resulting in fragment detachment and gravity-driven accumulation.

Key Concept

Frost Wedging Mechanics and Scree Formation
Question 159Question →

Match each landform created by running water or groundwater processes with its correct defining characteristic.

Click a left item, then click its matching right item

Items

Polje
Plunge pool
Braided channel
Stalagmite

Matches

Show answer & explanation

Answer

Polje matches with the large flat-bottomed depression in limestone regions; Plunge pool matches with the deep basin at the base of a waterfall; Braided channel matches with the wide, shallow river network with mid-channel bars; Stalagmite matches with the calcite pillar growing upwards from a cave floor.
Each feature is correctly matched to its formation mechanism: a polje is a large solution depression in karst topography; a plunge pool is carved at a waterfall base by turbulent water action; a braided channel is formed by sediment deposition splitting river flow; and a stalagmite is an upward-growing cave deposit of calcium carbonate.

Step-by-Step Solution

1
Identify the karst surface feature formed by massive solution and cavern collapse.
Polje matches the description of a large flat-bottomed depression in limestone landforms.
Poljes represent an advanced stage of karst landform evolution where subterranean rivers and solution hollows coalesce into a wide flat plain.
2
Analyze the upper-course fluvial feature located beneath vertical drops in water channels.
Plunge pool matches the deep basin formed at the base of a waterfall.
Hydraulic action and abrasion by swirling sediments rapidly deepen the channel floor directly below waterfalls.
3
Classify the depositional fluvial channel form containing mid-stream islands or bars.
Braided channel matches the shallow network created by heavy sediment deposition.
When stream energy drops relative to its heavy sediment load, channels split and recombine around sediment bars.
4
Determine the subterranean dripstone feature that builds upward from cave floors.
Stalagmite matches the upward-growing calcite pillar.
Dripping water loses carbon dioxide upon entering the cavern atmosphere, precipitating calcium carbonate on the floor beneath the drip point.

Key Concept

Classification of Fluvial and Karst Geomorphic Features
Estimated Time:1m 30s
Question 160Question →

Which of the following landforms is created primarily by wind deposition in arid environments?

Show answer & explanation

Answer: Barchan dune

Answer

The barchan dune is a landform formed by wind deposition in arid environments.
The barchan dune is a characteristic crescent-shaped dune formed by aeolian deposition where wind direction is dominant and sand supply is moderate.

Step-by-Step Solution

1
Identify the primary geomorphic agent requested in the question stem.
The agent specified is wind (aeolian process) operating in an arid environment via deposition.
Differentiating between erosional and depositional aeolian landforms is necessary to isolate the correct feature.
2
Evaluate the landform choices based on their active process and shaping agent.
Barchans are crescent-shaped sand dunes formed when wind deposits sand grains. Oxbow lakes and levees are fluvial landforms created by running water, while scree slopes are produced by mechanical weathering and mass wasting.
Classifying each landform eliminates fluvial and mass wasting distractors.

Key Concept

Aeolian Depositional Landforms
Estimated Time:45s
PreviousPage 8 / 14Next