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Cameroon GCE O-Level Geology study materials
Cameroon GCE O-Level Geology study resources

Cameroon GCE O-Level Geology practice questions

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Question 1Geology (O-Level subject content)

Which type of rock forms directly from the cooling and solidification of molten material?

  1. Metamorphic rock
  2. Igneous rock Correct answer.
  3. Bioclastic limestone
  4. Sedimentary rock

Explanation

Igneous rocks crystallise from magma or lava as it cools, so they are the primary products of solidification from a melt. Sedimentary rocks form by deposition and lithification of fragments or precipitates, and metamorphic rocks form by recrystallisation of pre-existing rocks under heat and pressure.

Question 2Geology (O-Level subject content)

A mineral has a well-developed cleavage in three directions at right angles to each other. Which mineral is most likely being described?

  1. Olivine
  2. Halite Correct answer.
  3. Quartz
  4. Muscovite

Explanation

Halite has cubic cleavage, breaking into blocks with three cleavages mutually at 90 degrees. Quartz shows conchoidal fracture with no true cleavage, muscovite has one perfect cleavage giving sheets, and olivine breaks with conchoidal fracture.

Question 3Geology (O-Level subject content)

Which term describes the process by which loose sediment is converted into solid rock?

  1. Lithification Correct answer.
  2. Metamorphism
  3. Foliation
  4. Erosion

Explanation

Lithification covers the compaction and cementation that turn loose sediment into coherent sedimentary rock. Erosion removes material, metamorphism recrystallises existing rock, and foliation is a metamorphic fabric.

Question 4Geology (O-Level subject content)

What is the name of the boundary where two tectonic plates move apart from each other?

  1. Subduction zone
  2. Convergent boundary
  3. Divergent boundary Correct answer.
  4. Transform boundary

Explanation

At a divergent boundary the plates separate and new lithosphere is created by upwelling magma, as along mid-ocean ridges. Convergent boundaries involve plates moving together, transform boundaries involve lateral sliding, and a subduction zone is a form of convergence.

Question 5Geology (O-Level subject content)

Which of the following is the hardest mineral on the Mohs scale?

  1. Corundum
  2. Topaz
  3. Quartz
  4. Diamond Correct answer.

Explanation

Diamond is assigned hardness 10, the top of the Mohs scale, because it scratches every other listed mineral. Corundum is 9, topaz is 8 and quartz is 7 on the same scale.

Question 6Geology (O-Level subject content)

Which layer of the Earth is composed mainly of solid iron and nickel and lies beneath the mantle?

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

Explanation

The inner core is solid iron-nickel alloy despite very high temperature because pressure is extreme. The outer core is also iron-nickel but liquid, the mantle is silicate rock, and the lithosphere is the rigid outer shell.

Question 7Geology (O-Level subject content)

Which of these features is characteristic of a sedimentary rock?

  1. Interlocking crystalline texture
  2. Layering or bedding Correct answer.
  3. Preferred alignment of platy minerals
  4. Glass-rich chilled margins

Explanation

Sedimentary rocks are deposited in layers, producing bedding that reflects successive episodes of deposition. Preferred alignment of platy minerals is a metamorphic fabric, interlocking crystals are typical of igneous and metamorphic rocks, and chilled margins occur in igneous bodies.

Question 8Geology (O-Level subject content)

Which type of weathering is the breakdown of rock by the growth of salt crystals in pores and cracks?

  1. Hydrolysis
  2. Biological weathering
  3. Carbonation
  4. Salt crystallisation Correct answer.

Explanation

Salt crystallisation is a physical process in which salts precipitating from pore water expand and prise rock apart. Carbonation and hydrolysis are chemical processes, and biological weathering involves the action of organisms.

Question 9Geology (O-Level subject content)

A river flows from a mountainous source to the sea. Which change in its load and channel is expected downstream?

  1. The load disappears completely and the channel deepens
  2. The load becomes finer and the channel becomes wider Correct answer.
  3. The load becomes coarser and the channel becomes narrower
  4. The load becomes coarser and the gradient steepens

Explanation

Downstream, the river's competence and energy per unit length fall, so coarse material is deposited upstream and finer material is carried further. Discharge increases downstream, so the channel typically widens and deepens and the gradient flattens.

Question 10Geology (O-Level subject content)

A rock sample is dark, fine-grained and contains abundant ferromagnesian minerals. Which rock is it most likely to be?

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

Explanation

Basalt is a dark, fine-grained mafic volcanic rock rich in ferromagnesian minerals such as pyroxene and olivine. Granite is coarse-grained and felsic, limestone is a light-coloured carbonate sedimentary rock, and quartzite is a pale metamorphic rock dominated by quartz.

Question 11Geology (O-Level subject content)

Which pair of plate boundaries is most closely associated with the formation of fold mountains?

  1. Divergent boundaries between oceanic plates
  2. Transform boundaries between continental plates
  3. Divergent boundaries within a single plate
  4. Convergent boundaries between continental plates Correct answer.

Explanation

Fold mountains form where continental plates collide, compressing and thickening the crust so that strata are folded and uplifted. Divergence creates rifts and ridges, and transform boundaries produce strike-slip faulting rather than large-scale folding.

Question 12Geology (O-Level subject content)

A sequence of sedimentary beds shows a fining-upward trend from coarse sandstone to shale. What does this most likely indicate about the depositional environment?

  1. Increasing transport energy with time
  2. Rapid cooling of a magma body
  3. A period of intense metamorphism
  4. Decreasing transport energy with time Correct answer.

Explanation

A fining-upward sequence records a progressive fall in the energy of the transporting medium, so coarser grains settle first and finer material later. Metamorphism and magma cooling cannot produce a grain-size trend in sedimentary beds.

Question 13Geology (O-Level subject content)

Which property of a mineral is tested by observing the colour of its powdered form on an unglazed porcelain plate?

  1. Streak Correct answer.
  2. Lustre
  3. Specific gravity
  4. Cleavage

Explanation

Streak is the colour of the mineral's powder, obtained by rubbing it on a porcelain streak plate, and it is often more consistent than the colour of the bulk specimen. Lustre describes the way a surface reflects light, cleavage describes breakage planes, and specific gravity is a density ratio.

Question 14Geology (O-Level subject content)

Which of the following best describes the process of metamorphism?

  1. Recrystallisation of solid rock under changed heat and pressure Correct answer.
  2. Melting of rock followed by crystallisation
  3. Precipitation of salts from evaporating seawater
  4. Deposition of sediment in a river delta

Explanation

Metamorphism is the solid-state recrystallisation of a pre-existing rock in response to changed temperature, pressure or chemically active fluids. Melting produces magma and then igneous rock, while deposition and evaporation are sedimentary processes.

Question 15Geology (O-Level subject content)

An earthquake's epicentre is located far from a populated town, yet the town experiences strong shaking. Which factor best explains this?

  1. The town lies on soft, water-saturated alluvium that amplifies ground motion Correct answer.
  2. The earthquake had a very shallow focus beneath the town
  3. The town lies exactly above the focus of the earthquake
  4. The town is underlain by hard, continuous bedrock that transmits seismic waves efficiently

Explanation

Soft, water-saturated sediments can amplify seismic shaking, so a distant epicentre may still cause strong damage on such ground. Hard bedrock generally damps shaking, and the focus cannot lie beneath the town if the epicentre is far away.

Question 16Geology (O-Level subject content)

Which feature is produced by the deposition of material where a fast-flowing mountain stream enters a flatter valley?

  1. A gorge
  2. An alluvial fan Correct answer.
  3. A waterfall
  4. An oxbow lake

Explanation

When a steep stream loses gradient and velocity on entering flatter ground, its coarse load is deposited as a fan-shaped body called an alluvial fan. Waterfalls and gorges are erosional features, and oxbow lakes form on meandering lowland floodplains.

Question 17Geology (O-Level subject content)

Which of the following methods is the most reliable way to distinguish calcite from quartz in the field?

  1. Testing whether the mineral scratches glass
  2. Comparing the colour of the two specimens
  3. Measuring the size of the crystals
  4. Applying dilute hydrochloric acid to each specimen Correct answer.

Explanation

Calcite reacts with dilute hydrochloric acid, effervescing as carbon dioxide is released, whereas quartz does not react. Colour varies widely and is unreliable, crystal size depends on growth conditions, and both minerals can scratch glass, so that test does not separate them.

Question 18Geology (O-Level subject content)

A magma body intrudes between existing sedimentary layers and solidifies parallel to them. Which term describes the resulting igneous body?

  1. Batholith
  2. Volcanic neck
  3. Sill Correct answer.
  4. Dyke

Explanation

A sill is a tabular intrusion concordant with the layering of the host rock, whereas a dyke cuts across the layers. A batholith is a very large, deep-seated intrusion, and a volcanic neck is the solidified conduit of a former volcano.

Question 19Geology (O-Level subject content)

Which sequence correctly orders the processes that form a clastic sedimentary rock from a granite source?

  1. Transport, metamorphism, deposition, cementation
  2. Melting, crystallisation, weathering, deposition
  3. Deposition, weathering, compaction, metamorphism
  4. Weathering, transport, deposition, compaction and cementation Correct answer.

Explanation

Granite is broken down by weathering, the debris is transported, deposited, then compacted and cemented to form a clastic sedimentary rock. Melting and metamorphism belong to other parts of the rock cycle and do not lie on this pathway.

Question 20Geology (O-Level subject content)

A region shows deep, intensely weathered soils, abundant chemical weathering of feldspar, and rapid stream runoff. Which climate is most consistent with these observations?

  1. Hot and humid Correct answer.
  2. Cold and dry
  3. Polar and glacial
  4. Temperate and arid

Explanation

Hot, humid conditions supply abundant water and high temperatures that accelerate hydrolysis of feldspar and deep chemical weathering. Cold, dry or arid climates limit chemical reaction and favour physical breakdown instead.

Question 21Geology (O-Level subject content)

Which statement best explains why oceanic lithosphere is subducted beneath continental lithosphere at a convergent boundary?

  1. Oceanic lithosphere is hotter than continental lithosphere
  2. Oceanic lithosphere is older than continental lithosphere
  3. Oceanic lithosphere is denser than continental lithosphere Correct answer.
  4. Oceanic lithosphere is thicker than continental lithosphere

Explanation

Oceanic lithosphere is composed of mafic rock and is denser than the thicker, more felsic continental lithosphere, so it sinks into the mantle when the two converge. Thickness, temperature and age are not the controlling reason in this comparison.

Question 22Geology (O-Level subject content)

In a graded bed, the grains become coarser upward. Which interpretation is most defensible?

  1. The bed was deposited from a melt that cooled slowly
  2. The bed was deposited by a single turbidity current that waned over time
  3. The sediment was deposited by a current whose energy increased over time Correct answer.
  4. The bed was metamorphosed after deposition

Explanation

Normal grading, with coarse grains at the base and fine grains at the top, records a waning current. A coarsening-upward bed therefore records the reverse, a current whose energy increased during deposition. Slow cooling of a melt and later metamorphism cannot produce a sedimentary grain-size gradient of this kind.

Question 23Geology (O-Level subject content)

A rock contains aligned platy minerals and shows a silky sheen with closely spaced cleavage surfaces. Which rock and grade are most consistent with these features?

  1. Slate, low-grade metamorphism Correct answer.
  2. Gneiss, high-grade metamorphism
  3. Marble, contact metamorphism
  4. Hornfels, contact metamorphism

Explanation

Slate is a low-grade metamorphic rock in which fine mica flakes are aligned to give slaty cleavage and a silky sheen. Gneiss shows coarse banding at high grade, marble is a non-foliated carbonate rock, and hornfels is a non-foliated contact-metamorphic rock.

Question 24Geology (O-Level subject content)

A mineral specimen is scratched by a copper coin but not by a fingernail, and it is not scratched by a steel file. Which statement about its hardness is most accurate?

  1. Its hardness cannot be estimated from these tests
  2. Its hardness is greater than that of a steel file
  3. Its hardness lies between that of a copper coin and a steel file Correct answer.
  4. Its hardness lies between that of a fingernail and a copper coin, and it is softer than steel

Explanation

The specimen resists a fingernail and a copper coin but is scratched by neither, while a steel file does scratch it, so its hardness falls between copper and steel on the Mohs scale. The tests bracket the value from both sides, which allows a reliable estimate.

Question 25Geology (O-Level subject content)

Two rock samples come from the same lava flow. One is glassy with a chilled margin, the other is coarse-grained. Which explanation is most consistent with igneous processes?

  1. Both samples cooled at identical rates but differed in water content
  2. The coarse sample is sedimentary and the glassy sample is metamorphic
  3. The glassy sample cooled rapidly at the surface and the coarse sample cooled slowly at depth Correct answer.
  4. The coarse sample cooled rapidly at the surface and the glassy sample cooled slowly at depth

Explanation

Cooling rate controls crystal size: rapid cooling at or near the surface produces fine-grained or glassy rock, while slow cooling at depth allows large crystals to grow. Differences in water content or rock type do not explain the observed textures within a single flow.

Question 26Geology (O-Level subject content)

Which term describes the surface along which two rock masses have moved past one another during an earthquake?

  1. Fault plane Correct answer.
  2. Fold axis
  3. Cleavage plane
  4. Bedding plane

Explanation

A fault is a fracture along which displacement has occurred, and the fault plane is the surface of that displacement. Bedding and cleavage are planar structures formed during deposition and deformation respectively, not by slip.

Question 27Geology (O-Level subject content)

Which gas is most abundant in the Earth's present atmosphere and is released mainly by volcanic degassing?

  1. Argon
  2. Nitrogen Correct answer.
  3. Carbon dioxide
  4. Oxygen

Explanation

Nitrogen makes up about 78 percent of the modern atmosphere and is the main volcanic gas after water vapour. Oxygen is produced largely by photosynthesis, while carbon dioxide and argon are far less abundant.

Question 28Geology (O-Level subject content)

A crystal of a mineral shows smooth flat surfaces that reflect light and meet at definite angles. Which term describes these surfaces?

  1. Lustre planes
  2. Fracture surfaces
  3. Crystal faces Correct answer.
  4. Cleavage faces

Explanation

Crystal faces are the natural flat surfaces that bound a crystal and grow with the ordered internal lattice, meeting at characteristic angles. Cleavage is a breakage property, and fracture describes irregular breakage.

Question 29Geology (O-Level subject content)

Which soil horizon is richest in decomposed organic matter and is usually dark in colour?

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

Explanation

The A horizon is the topsoil, where humus accumulates from decaying plant and animal remains, giving it a dark colour. The B horizon is a zone of accumulation of clay and iron, the C horizon is weathered parent material, and the R horizon is solid bedrock.

Question 30Geology (O-Level subject content)

Which process transports dissolved ions such as calcium and bicarbonate in a river?

  1. Traction
  2. Suspension
  3. Solution Correct answer.
  4. Saltation

Explanation

Solution is the transport of material dissolved in water, so the load is invisible and cannot settle until conditions change chemically. Traction and saltation move solid grains along the bed, and suspension carries fine grains within the water column.

Question 31Geology (O-Level subject content)

Which type of unconformity separates tilted older sedimentary beds from flat-lying younger beds above them?

  1. Paraconformity
  2. Disconformity
  3. Nonconformity
  4. Angular unconformity Correct answer.

Explanation

An angular unconformity forms when older beds are tilted or folded, eroded to a flat surface, and then buried by younger horizontal beds. A disconformity involves erosion between parallel beds, and a nonconformity lies on igneous or metamorphic rock.

Question 32Geology (O-Level subject content)

Which mineral is the commonest constituent of beach sand and is hard enough to resist abrasion during transport?

  1. Calcite
  2. Quartz Correct answer.
  3. Halite
  4. Gypsum

Explanation

Quartz is hard, chemically stable and resistant to weathering, so it survives repeated transport and concentrates in sandy deposits. Calcite, gypsum and halite are softer and dissolve or abrade readily.

Question 33Geology (O-Level subject content)

Which dating method uses the known decay of an isotope in a mineral to give an absolute age in years?

  1. Faunal succession
  2. Law of superposition
  3. Cross-cutting relationships
  4. Radiometric dating Correct answer.

Explanation

Radiometric dating measures the ratio of parent to daughter isotopes in a mineral and converts it into an age using the decay constant. The other choices establish relative order only.

Question 34Geology (O-Level subject content)

A lava flow has a ropy, wrinkled surface produced by the flow of viscous lava. Which term is used for this surface?

  1. Pahoehoe Correct answer.
  2. A'a
  3. Columnar jointing
  4. Pillow

Explanation

Pahoehoe is a smooth, ropy basaltic lava surface formed when fluid lava continues to move beneath a chilled skin. A'a is a rough, blocky surface, pillows form under water, and columnar joints are cooling fractures.

Question 35Geology (O-Level subject content)

A breccia differs from a conglomerate mainly because breccia consists of clasts that are:

  1. well rounded and sorted
  2. angular and poorly sorted Correct answer.
  3. chemically precipitated
  4. made of shell fragments

Explanation

Both rocks are coarse clastic rocks, but the clast shape records transport history. Angular, poorly sorted fragments in breccia indicate little transport, whereas rounded clasts in conglomerate indicate abrasion during longer transport.

Question 36Geology (O-Level subject content)

A river's discharge doubles while its channel cross-section stays the same. What happens to its average flow velocity?

  1. It stays the same
  2. It doubles Correct answer.
  3. It halves
  4. It falls to one quarter

Explanation

Discharge equals cross-sectional area multiplied by average velocity. If the area is unchanged, velocity must rise in the same proportion as discharge, so doubling discharge doubles velocity.

Question 37Geology (O-Level subject content)

A rock is made of interlocking crystals of quartz, feldspar and mica, with no preferred orientation. Which rock type is this?

  1. Evaporite
  2. Clastic sedimentary
  3. Non-foliated igneous Correct answer.
  4. Foliated metamorphic

Explanation

Interlocking crystals of igneous minerals with random orientation indicate crystallisation from a melt without directed stress. Foliated metamorphic rocks show alignment, clastic rocks are made of grains, and evaporites are chemical precipitates.

Question 38Geology (O-Level subject content)

Which feature best indicates that a magma was highly viscous during eruption?

  1. A steep-sided dome or thick lava flow Correct answer.
  2. Widespread flood basalt
  3. A broad shield profile
  4. Pillow lava on the sea floor

Explanation

High viscosity prevents lava from flowing far, so it piles up near the vent as a steep dome or short thick flow. Low-viscosity basalt spreads widely to give shields, flood basalt fields and pillow lavas.

Question 39Geology (O-Level subject content)

Which of these is a direct method of investigating the Earth's internal structure?

  1. Studying seismic wave paths
  2. Measuring gravity variations
  3. Interpreting magnetic anomalies
  4. Examining rocks in a deep borehole Correct answer.

Explanation

Direct methods sample the Earth itself, such as boreholes, mines and volcanic ejecta. Seismic, gravity and magnetic studies are indirect geophysical methods that infer structure from measurements at the surface.

Question 40Geology (O-Level subject content)

A mineral leaves a pale streak on a porcelain plate even though the hand specimen is dark. What does this show?

  1. The mineral is very hard
  2. The streak colour is more reliable than the specimen colour Correct answer.
  3. The mineral has metallic lustre
  4. The mineral has perfect cleavage

Explanation

Streak is the colour of the powdered mineral and is generally more constant than the colour of the hand specimen, which can vary with impurities or weathering. It gives no information about hardness or cleavage.

Question 41Geology (O-Level subject content)

A rock is composed almost entirely of interlocking calcite crystals and fizzes vigorously in dilute acid. Which rock is it?

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

Explanation

Marble is the metamorphosed product of limestone and consists of recrystallised calcite, which reacts strongly with dilute acid. Quartzite, slate and gneiss are dominated by silicate minerals that do not fizz.

Question 42Geology (O-Level subject content)

A coastline has a series of groynes built across the beach. Which change is most likely immediately downdrift of the groynes?

  1. Rapid deposition of sand
  2. Increased erosion of the beach Correct answer.
  3. Deepening of an offshore trench
  4. Growth of a coral reef

Explanation

Groynes trap sediment moving along the shore, so the beach grows on the updrift side but is starved of sand, and therefore eroded, on the downdrift side. Reef and trench formation are unrelated to groynes.

Question 43Geology (O-Level subject content)

Two sites lie at the same latitude, but one is at 200 m and the other at 2 000 m above sea level. Which difference is expected?

  1. The high site is warmer and wetter
  2. Both sites have identical temperature
  3. The high site is cooler and more exposed Correct answer.
  4. The high site has no rainfall

Explanation

Temperature falls with altitude at roughly 6.5 degrees Celsius per kilometre in the troposphere, and higher ground is more exposed to wind and orographic cloud. Latitude alone does not determine temperature.

Question 44Geology (O-Level subject content)

A sedimentary bed contains fragments of an underlying granite. What can be concluded about the ages of the two units?

  1. The bed is older than the granite
  2. Both formed at the same time
  3. The granite must be younger
  4. The granite is older than the bed Correct answer.

Explanation

Inclusions within a rock must already exist when the host material forms, so the included granite is older than the sedimentary bed that contains its fragments. This is the principle of included fragments.

Question 45Geology (O-Level subject content)

A fold has its limbs dipping away from a central axis and the oldest beds occur in the core. Which structure is described?

  1. Fault scarp
  2. Anticline Correct answer.
  3. Monocline
  4. Syncline

Explanation

An anticline is an upfold with limbs dipping away from the axis and the oldest strata exposed in the core. A syncline is a downfold with the youngest beds in the core.

Question 46Geology (O-Level subject content)

Why do transform faults generate earthquakes but little or no volcanic activity?

  1. Subduction destroys all magma
  2. Magma is generated but trapped at depth
  3. The rocks there are too cold to fracture
  4. Plates slide past each other without significant magma generation Correct answer.

Explanation

At a transform boundary the plates move horizontally past one another, so there is no addition or loss of lithosphere and no decompression melting. Friction between the blocks builds stress that is released as earthquakes.

Question 47Geology (O-Level subject content)

A sandstone bed shows large-scale cross-bedding with foresets dipping steeply to the south. What does this indicate about the depositional environment?

  1. Deposition by currents flowing towards the south Correct answer.
  2. Deposition from a quiet, still water body
  3. Deposition from a glacier
  4. Chemical precipitation in a lake

Explanation

Cross-bedding forms as migrating bedforms advance, and the foresets dip in the direction of current flow. Steep foresets indicate transport by relatively strong currents, here towards the south.

Question 48Geology (O-Level subject content)

During regional metamorphism, a shale is buried progressively deeper. Which sequence of rocks is expected with increasing grade?

  1. Gneiss, schist, phyllite, slate
  2. Slate, phyllite, schist, gneiss Correct answer.
  3. Schist, slate, gneiss, phyllite
  4. Marble, quartzite, slate, schist

Explanation

Increasing temperature and pressure cause clay minerals in shale to recrystallise and coarsen, producing slate, then phyllite, then schist and finally gneiss. The other sequences run against the metamorphic grade.

Question 49Geology (O-Level subject content)

A confined aquifer is capped by an impermeable layer and its potentiometric surface lies above the ground surface. What happens when a well is drilled into it?

  1. Water must be pumped from great depth
  2. Water flows downwards into the aquifer
  3. Water rises above the ground surface without pumping Correct answer.
  4. The well remains dry

Explanation

In a confined aquifer the water is under pressure because the recharge area is higher than the well head. If the potentiometric surface lies above ground level, the well is artesian and water rises unaided.

Question 50Geology (O-Level subject content)

A seismograph records P waves arriving 20 seconds before S waves. If the difference in arrival time increases to 40 seconds at a second station, what does this indicate?

  1. The second station is closer to the epicentre
  2. The earthquake was stronger at the second station
  3. The second station is farther from the epicentre Correct answer.
  4. The second station lies on harder rock

Explanation

The interval between P and S arrivals grows with distance from the focus because the slower S waves fall progressively further behind. A 40-second gap therefore indicates a greater distance than a 20-second gap.