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JC Geography practice questions

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Question 1The Earth's Surface and Processes

Which layer of the Earth's interior is composed mainly of solid iron and nickel and lies at the centre?

  1. The inner core Correct answer.
  2. The asthenosphere
  3. The outer core
  4. The lower mantle

Explanation

The inner core is the innermost zone of the Earth and is solid because of extremely high pressure, despite temperatures of several thousand degrees. Its composition is dominated by iron with some nickel. The outer core is also iron-rich but is liquid.

Question 2The Earth's Surface and Processes

The theory that continents have drifted across the Earth's surface over geological time was first proposed in the early twentieth century by which scientist?

  1. Harry Hess
  2. Alfred Wegener Correct answer.
  3. James Hutton
  4. Charles Lyell

Explanation

Alfred Wegener assembled evidence from matching coastlines, fossils and rock sequences to argue that continents had once been joined and later drifted apart. His idea of continental drift was later incorporated into plate tectonics. Hess, by contrast, proposed sea-floor spreading.

Question 3The Earth's Surface and Processes

A river flows from a steep upland into a wide lowland basin. Which change in the river's behaviour is most likely as it enters the lowland?

  1. Its load becomes entirely dissolved material
  2. Its discharge falls sharply because evaporation increases
  3. Its channel becomes narrower and more deeply incised
  4. Its gradient decreases and deposition becomes more dominant Correct answer.

Explanation

As gradient decreases in a lowland, flow velocity falls, reducing the river's competence to carry sediment. Deposition therefore becomes more important than erosion, building floodplains and levees. Discharge normally increases downstream as tributaries add water.

Question 4The Earth's Surface and Processes

Which term describes the downslope movement of a mass of rock and soil along a curved slip surface?

  1. A rockfall
  2. A rotational slump Correct answer.
  3. A debris flow
  4. A solifluction lobe

Explanation

A rotational slump involves a coherent block sliding along a concave, spoon-shaped shear plane, often leaving a back scar. The moving mass tends to rotate and pile up at its toe. Rockfall, solifluction and debris flow involve different mechanisms.

Question 5The Earth's Surface and Processes

Which type of plate boundary is associated with the formation of new oceanic lithosphere?

  1. A divergent boundary at a mid-ocean ridge Correct answer.
  2. A passive continental margin
  3. A transform boundary along a major fault
  4. A convergent boundary at an ocean trench

Explanation

At mid-ocean ridges, mantle upwelling and decompression melting create magma that solidifies to form new oceanic crust, so the plates move apart. This process, sea-floor spreading, adds lithosphere. Trenches and transform faults do not create new crust.

Question 6The Earth's Surface and Processes

Which process is the main way that groundwater erodes and dissolves limestone to form caves?

  1. Freeze-thaw weathering
  2. Carbonation solution Correct answer.
  3. Hydraulic action
  4. Abrasion by bed load

Explanation

Rainwater absorbs carbon dioxide from air and soil to form weak carbonic acid, which dissolves calcium carbonate in limestone along joints and bedding planes. This carbonation solution enlarges fissures into caves. The other processes act mainly on clastic rocks or in other environments.

Question 7The Earth's Surface and Processes

Which feature is produced by glacial deposition rather than glacial erosion?

  1. A U-shaped valley
  2. A cirque
  3. A terminal moraine Correct answer.
  4. A roche moutonnée

Explanation

Moraines are ridges of unsorted till deposited at the margin or beneath a glacier. They record where material was released as ice melted. Cirques, roche moutonnées and U-shaped valleys are all landforms carved by erosion.

Question 8The Earth's Surface and Processes

Which factor most directly increases the risk of a mass movement on a hillslope?

  1. Removal of vegetation from the slope by grazing
  2. Continued weathering of bedrock into clay
  3. A decrease in the slope angle
  4. Saturation of the regolith with water after heavy rain Correct answer.

Explanation

Water saturating the regolith raises pore-water pressure and adds weight, both of which reduce shear strength and increase shear stress, so failure becomes likely. Slope angle change, vegetation removal and weathering affect stability but are not the immediate trigger in the same direct way.

Question 9The Earth's Surface and Processes

A fast-flowing river carrying a heavy suspended load enters a lake. Which deposit is most likely to form where the river meets the lake?

  1. A delta of coarse sediment dropping out first Correct answer.
  2. A deep-sea turbidite fan
  3. An alluvial fan on the hillslope
  4. A point bar on the inner bend

Explanation

When a river enters standing water, velocity falls abruptly and the bed load and coarser suspended load are deposited first, building a delta. The finest sediment is carried farther into the lake. Turbidites, alluvial fans and point bars form in other settings.

Question 10The Earth's Surface and Processes

Which combination of plate boundary and process best explains the deep ocean trench and volcanic island arc of the western Pacific?

  1. Ocean-ocean convergence with subduction Correct answer.
  2. Divergence at a mid-ocean ridge
  3. Continental collision with folding
  4. Transform faulting with lateral slip

Explanation

Where two oceanic plates converge, the older, denser plate subducts, producing a trench. Water released from the descending slab lowers the melting point of the overlying mantle, generating magma that rises to form an island arc. Continental collision, divergence and transform faulting produce different features.

Question 11The Earth's Surface and Processes

Which statement best explains why freeze-thaw weathering is most effective in upland temperate and periglacial environments?

  1. Frequent cycles of freezing and thawing allow water in cracks to expand repeatedly Correct answer.
  2. Constant rainfall removes weathered material faster than it forms
  3. High temperatures cause rapid chemical reaction with rock minerals
  4. Thick vegetation produces organic acids that dissolve bedrock

Explanation

Freeze-thaw requires water in joints to freeze and expand, then thaw and drain, so repeated cycles pry the rock apart. Such cycles are frequent where temperatures fluctuate around the freezing point, as in uplands and periglacial zones. The other options describe chemical or biological weathering.

Question 12The Earth's Surface and Processes

A coastline experiences strong onshore winds and abundant sand supply. Which landform is most likely to develop parallel to the shore?

  1. A sea stack and stump
  2. A sandy beach backed by dunes Correct answer.
  3. A wave-cut notch
  4. A blowhole in a cliff

Explanation

Onshore winds move dry sand inland from the beach, building dunes, while wave action and longshore drift maintain the beach. The beach and dune system therefore lies parallel to the shore. Sea stacks, blowholes and wave-cut notches are erosional features of rocky coasts.

Question 13The Earth's Surface and Processes

Which sequence correctly describes the development of a karst cave system from surface drainage?

  1. Glacial plucking, deposition of till, then meltwater erosion
  2. Wind abrasion, deflation, then dune formation
  3. Wave attack, cliff retreat, then arch formation
  4. Joint widening by solution, underground drainage, cave enlargement and collapse Correct answer.

Explanation

Carbonation solution widens joints on the limestone surface, allowing water to sink underground. Continued solution along the water table enlarges passages into caves, and eventual roof collapse may create a gorge or collapse doline. The other sequences describe glacial, aeolian and coastal processes.

Question 14The Earth's Surface and Processes

Which evidence best supports the theory of sea-floor spreading?

  1. The occurrence of earthquakes at shallow depths only
  2. The presence of folded mountain belts at continental interiors
  3. Symmetrical magnetic striping on either side of a mid-ocean ridge Correct answer.
  4. Matching fossil plants on now-separated continents

Explanation

As new crust forms at a ridge, magnetic minerals record the prevailing field direction, producing parallel stripes of normal and reversed polarity on both sides. Their symmetry shows that crust has moved away from the ridge over time. Continental fossil matches support drift but not spreading directly.

Question 15The Earth's Surface and Processes

Which landform is characteristic of a glaciated upland and is formed by erosion at the head of a valley?

  1. An esker
  2. A kame terrace
  3. A drumlin field
  4. A cirque with a tarn Correct answer.

Explanation

A cirque is an armchair-shaped hollow eroded by a small glacier at the head of a valley, and it may later hold a tarn. Drumlins, eskers and kame terraces are all depositional features.

Question 16The Earth's Surface and Processes

A slope consists of permeable sandstone overlying impermeable clay. After prolonged rainfall, which condition most increases the likelihood of failure along the contact?

  1. The sandstone becomes denser and more resistant to sliding
  2. The clay layer expands and binds the overlying rock
  3. Water percolating to the clay layer raises pore pressure and lubricates the contact Correct answer.
  4. Rainfall removes the sandstone by solution

Explanation

Percolating water reaches the impermeable clay and accumulates, raising pore-water pressure along the contact. This reduces effective normal stress and friction, while the added weight increases shear stress, promoting sliding. Sandstone is not dissolved by rainfall on this scale.

Question 17The Earth's Surface and Processes

Which statement correctly distinguishes weathering from erosion?

  1. Erosion is chemical only, whereas weathering is physical only
  2. Weathering transports material, whereas erosion only breaks it down
  3. Weathering breaks rock down in situ, whereas erosion involves transport of the debris Correct answer.
  4. Both terms describe the same process of rock decay

Explanation

Weathering is the disintegration or decomposition of rock in place, producing regolith without movement. Erosion involves the detachment and transport of that material by agents such as water, ice or wind. The two processes are related but distinct.

Question 18The Earth's Surface and Processes

Which factor most strongly determines the shape of a river delta?

  1. The balance between river sediment supply and wave or tidal energy Correct answer.
  2. The temperature of the river water
  3. The depth of the underlying bedrock only
  4. The number of meanders upstream

Explanation

Where river discharge and sediment supply dominate over wave and tidal reworking, deltas protrude as bird's-foot forms. Where waves or tides are strong, sediment is redistributed into smoother, cuspate or estuarine shapes. Water temperature and upstream meanders have little direct influence.

Question 19The Earth's Surface and Processes

Which feature is formed by longshore drift?

  1. A blowhole
  2. A sea arch
  3. A wave-cut platform
  4. A spit extending across a bay mouth Correct answer.

Explanation

Longshore drift moves sediment along the coast in the direction of the prevailing swash. Where the coastline changes direction, the drifting sediment may build a spit across the bay. Platforms, arches and blowholes are all erosional features.

Question 20The Earth's Surface and Processes

Which statement best explains why steep, unvegetated slopes in semi-arid regions experience rapid runoff and gully erosion?

  1. Rock is dissolved rapidly by carbonation
  2. Sparse vegetation and thin soil reduce infiltration, so overland flow is concentrated Correct answer.
  3. Wind removes all the soil before rain falls
  4. High rainfall intensity is the only controlling factor

Explanation

In semi-arid regions, vegetation cover is sparse and soils are thin, so little rain infiltrates. During intense storms, overland flow concentrates in rills and enlarges them into gullies. Rainfall intensity matters, but infiltration capacity and cover are the key controls.

Question 21The Earth's Surface and Processes

A geologist finds pillow lavas and sheeted dyke complexes in an ancient mountain belt. Which interpretation is most consistent with these rocks?

  1. They were erupted explosively on a continental interior
  2. They formed at an ancient spreading ridge later incorporated into the mountain belt Correct answer.
  3. They were deposited by glacial meltwater on a continental shelf
  4. They formed by chemical precipitation in a shallow lake

Explanation

Pillow lavas form when lava is erupted under water, and sheeted dyke complexes are characteristic of oceanic crust created at spreading ridges. Their presence in a mountain belt indicates that a fragment of oceanic crust was obducted or accreted during convergence. Glacial, continental and lacustrine settings cannot produce this association.

Question 22The Earth's Surface and Processes

A cliff of alternating hard and soft rock beds retreats under wave attack. Which resulting coastline profile is most likely?

  1. A smooth sandy beach with no headlands
  2. Bays eroded into soft rock separated by headlands of hard rock Correct answer.
  3. A wide marshy plain extending far inland
  4. A perfectly straight cliff line of uniform height

Explanation

Differential erosion occurs because soft beds are worn back faster than resistant beds, producing indented coastlines of bays and headlands. The headlands then experience wave refraction and further erosion. Uniform or marshy coasts require different geological and energy conditions.

Question 23The Earth's Surface and Processes

Which explanation best accounts for the high seismicity and volcanism along the Pacific Ring of Fire?

  1. Mantle plumes fixed beneath the ocean floor
  2. Uniform sea-floor spreading at the ocean centre
  3. A single transform fault crossing the entire ocean
  4. A series of subduction zones around the Pacific margin Correct answer.

Explanation

The Ring of Fire follows convergent margins where oceanic plates subduct beneath continental or oceanic plates. Subduction generates deep earthquakes and magma, producing chains of volcanoes. A single transform fault, uniform spreading or fixed plumes cannot explain the ring-shaped distribution.

Question 24The Earth's Surface and Processes

A river's long profile shows a concave shape with a steep upper course and gentle lower course. Which combination of processes best explains this profile?

  1. Deposition dominant upstream and erosion dominant downstream
  2. Uniform erosion along the entire course
  3. Erosion dominant in the upper course and deposition dominant in the lower course over time Correct answer.
  4. Tectonic uplift at the mouth and subsidence at the source

Explanation

Rivers erode vigorously where gradients are steep, lowering the upper profile, while deposition in lowland reaches raises the bed. Over time these processes smooth the profile towards a graded, concave form. Uniform erosion or uplift at the mouth would not produce this shape.

Question 25The Earth's Surface and Processes

Which evidence would most strongly indicate that a landscape was formerly glaciated rather than shaped only by rivers?

  1. Alluvial fans at the foot of a mountain front
  2. Meanders with point bars on a floodplain
  3. Hanging valleys and truncated spurs along a broad U-shaped trough Correct answer.
  4. V-shaped valleys with interlocking spurs

Explanation

Glacial erosion deepens and widens valleys into U-shaped troughs and truncates spurs, while tributary valleys are left hanging above the main trough. V-shaped valleys with interlocking spurs, meanders and alluvial fans are typical of fluvial processes. The association of these glacial features is diagnostic.

Question 26The Earth's Surface and Processes

Which term describes the downslope movement of weathered material under the direct influence of gravity, without the primary involvement of water, wind, or ice as transporting agents?

  1. Erosion
  2. Mass wasting Correct answer.
  3. Weathering
  4. Deposition

Explanation

Mass wasting is the geomorphic process by which soil and rock move downslope under the force of gravity. Although water can reduce friction and trigger failure, the transport itself is gravity-driven. Erosion involves transport by a mobile agent such as water, wind, or ice, and weathering is the breakdown of rock in situ.

Question 27The Earth's Surface and Processes

Which process is the primary cause of coastal erosion in a sea cave that eventually forms a blowhole?

  1. Abrasion
  2. Solution
  3. Hydraulic action Correct answer.
  4. Attrition

Explanation

Hydraulic action is the force of waves compressing air in joints and cracks, which can eventually force a passage upward to the surface. This compressed air explosively enlarges the crack, creating a blowhole. Abrasion, attrition, and solution act more gradually and are not the primary mechanism for blowhole formation.

Question 28The Earth's Surface and Processes

Which factor most directly controls the angle of repose of a pile of dry sand?

  1. Grain size and shape Correct answer.
  2. Vegetation cover
  3. Slope aspect
  4. Rainfall intensity

Explanation

The angle of repose is the steepest angle at which a granular material remains stable. It depends primarily on grain size, shape, and sorting: angular, coarser grains interlock and support steeper angles than rounded, finer grains. Aspect, vegetation, and rainfall affect stability but do not define the angle of repose of dry sand.

Question 29The Earth's Surface and Processes

Which feature is a depositional landform created by a glacier?

  1. U-shaped valley
  2. Terminal moraine Correct answer.
  3. Cirque
  4. Arete

Explanation

A terminal moraine is a ridge of unsorted glacial till deposited at the maximum extent of a glacier. It is built up from material carried and then dropped by the ice. Cirques, aretes, and U-shaped valleys are all formed by glacial erosion.

Question 30The Earth's Surface and Processes

Which rock type is most likely to be exposed at the surface along a mid-ocean ridge?

  1. Shale
  2. Limestone
  3. Basalt Correct answer.
  4. Granite

Explanation

Mid-ocean ridges are divergent plate boundaries where basaltic magma rises to form new oceanic crust. Basalt is the dominant rock of the oceanic crust. Granite is typical of continental crust, and limestone and shale are sedimentary rocks not normally found at mid-ocean ridges.

Question 31The Earth's Surface and Processes

A slope consists of permeable sandstone overlying impermeable clay. After prolonged rainfall, which condition most increases the likelihood of slope failure?

  1. Water saturates the sandstone, raising pore pressure at the clay interface Correct answer.
  2. Rainwater infiltrates the clay and lubricates the bedding plane
  3. Clay expands and pushes the sandstone upwards
  4. Sandstone dissolves and removes support

Explanation

Prolonged rainfall infiltrates the permeable sandstone and percolates down to the impermeable clay. Water accumulates, increasing pore water pressure and reducing effective stress. This can trigger failure along the interface. Clay expansion, sandstone dissolution, and clay infiltration are less likely or incorrect.

Question 32The Earth's Surface and Processes

Which type of plate boundary is associated with the formation of new oceanic crust along a mid-ocean ridge?

  1. Passive margin
  2. Divergent boundary Correct answer.
  3. Transform boundary
  4. Convergent boundary

Explanation

At a divergent boundary, two plates move apart and magma rises to fill the gap, cooling to form new oceanic crust. This process, known as sea-floor spreading, builds the ridge system. Convergent and transform boundaries involve crust being destroyed or sliding past, not created.

Question 33The Earth's Surface and Processes

Which seismic wave type travels fastest and is the first to be recorded at a seismograph station?

  1. Primary (P) waves Correct answer.
  2. Rayleigh waves
  3. Love waves
  4. Secondary (S) waves

Explanation

P waves are compressional waves that travel through both solids and liquids at the highest velocity, so they arrive first. S waves are slower shear waves that cannot pass through liquids. Love and Rayleigh waves are surface waves and are the slowest arrivals.

Question 34The Earth's Surface and Processes

Which mineral property is defined as the colour of a powdered mineral sample rubbed on unglazed porcelain?

  1. Lustre
  2. Cleavage
  3. Hardness
  4. Streak Correct answer.

Explanation

Streak describes the colour of the powder left when a mineral is rubbed across a porcelain streak plate. It is often more reliable than the mineral's surface colour, which can vary with impurities. Lustre, cleavage and hardness describe how light reflects, how a mineral breaks, and resistance to scratching.

Question 35The Earth's Surface and Processes

Which rock is formed when limestone is subjected to high heat and pressure during metamorphism?

  1. Gneiss
  2. Marble Correct answer.
  3. Quartzite
  4. Slate

Explanation

Marble is the metamorphic product of limestone, recrystallised under heat and pressure. Slate derives from shale, quartzite from sandstone, and gneiss from high-grade metamorphism of various rocks such as granite or shale.

Question 36The Earth's Surface and Processes

Which layer of the atmosphere contains most of the weather systems and clouds affecting the Earth's surface?

  1. Mesosphere
  2. Troposphere Correct answer.
  3. Stratosphere
  4. Thermosphere

Explanation

The troposphere is the lowest atmospheric layer and holds most of the atmosphere's water vapour, so clouds and weather occur there. The stratosphere contains the ozone layer, the mesosphere is where meteors burn up, and the thermosphere is the upper, very thin layer.

Question 37The Earth's Surface and Processes

Which factor is the primary control on the rate of chemical weathering of limestone in a humid region?

  1. Colour of the rock surface
  2. Availability of carbonic acid in water Correct answer.
  3. Grain size of quartz crystals
  4. Wind speed at the surface

Explanation

Limestone weathers mainly by carbonation, in which carbonic acid dissolved in water reacts with calcium carbonate. The amount of carbonic acid available, controlled by rainfall and organic activity, therefore dominates the rate. Wind speed, quartz grain size and surface colour have little direct influence on this chemical reaction.

Question 38The Earth's Surface and Processes

A river flows from a steep upland onto a flat plain. Which change in its channel and load is most expected as it enters the plain?

  1. Increased turbulence and reduced deposition
  2. Increased gradient and increased competence
  3. Decreased gradient, reduced competence and more deposition Correct answer.
  4. Decreased discharge and increased erosion

Explanation

As gradient falls on entering a plain, flow velocity and turbulence decrease, so the river can carry less coarse material. Competence therefore drops and deposition of sediment begins. Erosion and turbulence do not increase when the gradient decreases.

Question 39The Earth's Surface and Processes

A meander loop is eventually cut off from the main channel. Which landform results?

  1. Floodplain terrace
  2. Oxbow lake Correct answer.
  3. Braided channel
  4. Levee

Explanation

When erosion on the outer bank and deposition on the inner bank cause a meander neck to be breached, the abandoned loop becomes an oxbow lake. Braided channels form where sediment load exceeds transport capacity, levees are raised banks of deposited sediment, and terraces are former floodplain levels left by incision.

Question 40The Earth's Surface and Processes

Which condition most favours the formation of a waterfall in a river's course?

  1. A wide, gently sloping floodplain
  2. A river channel with no vertical change in gradient
  3. Uniformly soft sediment along the bed
  4. A band of resistant rock overlying softer rock Correct answer.

Explanation

A waterfall commonly forms where a resistant rock band lies above softer rock; the softer rock erodes faster, creating a step and a vertical drop. Uniformly soft beds or gentle floodplains lack the differential erosion needed to create a fall.

Question 41The Earth's Surface and Processes

Which process is mainly responsible for the formation of an alluvial fan at the foot of a mountain front?

  1. Chemical dissolution of limestone
  2. Sudden loss of channel gradient and spreading of flow Correct answer.
  3. Wind deflation of loose sand
  4. Glacial plucking of bedrock

Explanation

A stream leaving a steep mountain front spreads out and loses velocity abruptly, so its sediment load is deposited as a fan. Glacial plucking, chemical dissolution and wind deflation produce different landforms such as cirques, karst and deflation hollows.

Question 42The Earth's Surface and Processes

Which soil horizon is typically the zone of greatest organic matter accumulation and biological activity?

  1. O horizon Correct answer.
  2. R horizon
  3. B horizon
  4. C horizon

Explanation

The O horizon is the surface layer of organic litter and humus where decomposition and biological activity are most concentrated. The B horizon is a subsoil zone of accumulation, the C horizon is weathered parent material, and the R horizon is unweathered bedrock.

Question 43The Earth's Surface and Processes

Which combination of conditions produces the greatest potential for mass movement on a hillside?

  1. Concave slope, coarse gravel and strong winds
  2. Flat ground, bedrock and low rainfall
  3. Steep slope, clay-rich soil and heavy rainfall Correct answer.
  4. Gentle slope, sandy soil and dry weather

Explanation

Mass movement is favoured where the driving force of gravity on a steep slope exceeds resisting friction. Clay-rich soil absorbs water, becomes heavier and may lose cohesion, while heavy rainfall adds weight and pore pressure. Gentle, flat or dry conditions reduce the driving stress.

Question 44The Earth's Surface and Processes

Which coastal process is chiefly responsible for the sorting of beach sediment so that finer material lies further offshore?

  1. Wind deposition of dust
  2. Glacial abrasion of bedrock
  3. Waves washing sediment of different sizes to different depths Correct answer.
  4. Chemical solution of calcium carbonate

Explanation

As waves shoal and break, they move sediment, and finer particles remain suspended longer and settle in deeper water offshore. Coarser material is deposited nearer the shore. Glacial abrasion, chemical solution and wind deposition do not produce this size sorting across a beach profile.

Question 45The Earth's Surface and Processes

Which feature forms where a river enters the sea and its sediment is deposited faster than it can be removed by tides and waves?

  1. Estuary
  2. Fjord
  3. Delta Correct answer.
  4. Ria

Explanation

A delta builds where a river's sediment supply exceeds the ability of tides and waves to disperse it at the mouth. Estuaries, rias and fjords are drowned river or glacial valleys formed by rising sea level or subsidence, not by sediment build-up.

Question 46The Earth's Surface and Processes

Which interpretation best explains a series of parallel ridges of glacial till running across a lowland?

  1. Wind deposition of loess over time
  2. Erosion by a river meandering across the plain
  3. Chemical weathering of limestone bedrock
  4. Deposition at the margin of a former ice sheet Correct answer.

Explanation

Parallel ridges of unsorted till mark former ice-margin positions, where material was deposited as the ice front paused or retreated. River meandering erodes and deposits alluvium in channels, chemical weathering dissolves bedrock, and loess is wind-blown silt forming blankets rather than till ridges.

Question 47The Earth's Surface and Processes

A region has high temperature and high rainfall throughout the year. Which weathering regime is most likely to dominate?

  1. Minimal weathering due to dry conditions
  2. Dominant freeze-thaw shattering of bedrock
  3. Dominant salt crystallisation in dry air
  4. Rapid chemical weathering with deep soil development Correct answer.

Explanation

High temperature accelerates chemical reaction rates, and abundant rainfall supplies the water needed for hydrolysis and carbonation, producing deep, leached soils. Freeze-thaw shattering requires repeated freezing, salt crystallisation requires dry conditions, and minimal weathering requires aridity.

Question 48The Earth's Surface and Processes

Two adjacent drainage basins are separated by a ridge. Which term describes the boundary between them?

  1. Tributary
  2. Catchment outlet
  3. Watershed Correct answer.
  4. Confluence

Explanation

A watershed, or drainage divide, is the ridge of high ground separating one drainage basin from another. A confluence is where two streams join, a tributary is a smaller stream feeding a larger one, and the outlet is the point where a basin's water leaves.

Question 49The Earth's Surface and Processes

A sedimentary sequence contains coarse conglomerate at the base, grading upward into sandstone and then shale. Which interpretation is most consistent with this pattern?

  1. A gradual decrease in depositional energy over time Correct answer.
  2. A sudden increase in current strength over time
  3. Deposition from a glacier without sorting
  4. Chemical precipitation from evaporating seawater

Explanation

A fining-upward sequence indicates that the energy of the transporting medium declined, allowing progressively finer sediment to settle. Conglomerate requires high energy, sandstone moderate energy, and shale low energy. A sudden increase in current strength would produce a coarsening-upward sequence instead.

Question 50The Earth's Surface and Processes

Which evidence best supports the interpretation that a valley was carved by a glacier rather than a river?

  1. A U-shaped cross-profile with truncated spurs Correct answer.
  2. A narrow V-shaped cross-profile with interlocking spurs
  3. A delta at the valley mouth
  4. A meandering channel on a floodplain

Explanation

Glaciers erode broad U-shaped troughs and truncate the spurs that rivers would leave interlocking, so a U-profile with truncated spurs indicates glacial erosion. V-shaped profiles, meanders and deltas reflect fluvial processes.