Geomorphology MCQ Quiz - Objective Question with Answer for Geomorphology - Download Free PDF

• Statement 1: Incorrect – Mantle plumes are not caused by plate tectonics and do not originate at the lithosphere–asthenosphere boundary. They are believed to rise from the core–mantle boundary.
• Statement 2: Correct – The Réunion hotspot is associated with the formation of the Deccan Traps around 66 million years ago.
• Statement 3: Correct – Flood basalt volcanism due to mantle plumes can form large igneous provinces (LIPs), covering thousands of square kilometers.
• Statement 4: Correct – Unlike tectonic plates, mantle plumes are relatively fixed in position, which helps identify hotspot tracks like the Hawaiian Islands.

Key Points

• Mantle Plumes: Definition and Characteristics
  • Convection of abnormally hot rock (magma) within the Earth's mantle.
  • Position appears relatively fixed, unlike larger mantle convection cells.
  • Theorized to form at the core-mantle boundary where abnormally hot rock accumulates.
  • Shaped like a mushroom: a long conduit (tail) connects the bulbous head to its base.
  • The head expands as the plume rises.
  • Rises through the Earth's mantle, becoming a diapir (dome-like intrusion) in the upper mantle (lower lithosphere).
• Mantle Plumes and Flood Basalt Volcanism (Large Igneous Provinces)
  • Responsible for extensive accumulations of flood basalts on continents.
  • Mantle plumes are a few hundred kilometers in diameter and rise slowly.
  • When a plume head reaches the base of the lithosphere, it flattens out.
  • This flattening causes widespread decompression melting, forming large volumes of basalt magma.
  • Basaltic magma can then erupt onto the surface through fissures, creating large igneous provinces (LIPs).
  • LIPs often occupy several thousand square kilometers.
• Examples and Impacts of Large Igneous Provinces (LIPs)
  • Examples: Iceland, Siberian Traps, Deccan Traps, Ontong Java Plateau.
  • Extensive regions of basalts on a continental scale, resulting from flood basalt eruptions.
  • Large amounts of volcanic material can cover vast areas with lava and ash.
  • Can cause long-lasting climate change (e.g., triggering a small ice age).
  • The Réunion hotspot produced the Deccan Traps about 66 million years ago, coinciding with the Cretaceous–Paleogene extinction event (K-T extinction).
  • While a meteor impact (Chicxulub Crater) was the primary cause of this extinction, volcanic activity may have contributed to environmental stresses.
  • The largest flood basalt event, the Siberian Traps, occurred around 250 million years ago, coinciding with the Permian–Triassic extinction event (the largest mass extinction in history).
• Mantle Plumes and Volcanic Hotspots
  • A mantle plume provides a continuous supply of abnormally hot magma to a fixed location in the mantle, known as a hotspot.
  • The high heat of the hotspot facilitates the melting of rock at the base of the lithosphere.
  • The melted rock (magma), under high pressure, often pushes through cracks in the crust to form hotspot volcanoes (e.g., Mount Mauna Kea).

Key Points

• What is Exfoliation?
  • Exfoliation is a physical weathering process where the outer layers of rocks peel off in thin sheets due to temperature fluctuations or pressure release. This process is commonly referred to as "onion skin" weathering.
• How it Happens:
  • Thermal Stress: Repeated heating and cooling cause rocks to expand and contract. This expansion and contraction create stress in the outer layers, causing fractures and leading to peeling off.
  • Unloading: When erosion removes overlying rock layers, the pressure on the underlying rocks decreases. This reduction in pressure allows the rocks to expand, which results in cracks and peeling.
• The process breaks down rocks without changing their chemical composition.
• It is typically found in regions with moderate to high rainfall and significant temperature fluctuations.
• Exfoliation is most visible in granitic rocks, which have layered structures that are more susceptible to this process.
• Exfoliation domes and tors are important landforms formed as a result of this weathering process

The correct answer is Sandstone.

• Sandstone is NOT a metamorphic rock.

Key Points

• Metamorphic rocks are rocks that have become changed by intense heat or pressure while forming.
  • In the very hot and pressured conditions deep inside the Earth's crust, both sedimentary and igneous rocks can be changed into metamorphic rock.
  • ​Metamorphic rock can be formed locally when rock is heated by the intrusion of hot molten rock called magma from the Earth's interior.
    • Some examples of metamorphic rocks are gneiss, slate, marble, schist, and quartzite.
  • Marble, Slate, and quartz are formed after metamorphism. They changed in their original form due to extreme temperatures and pressure.
  • The three types of metamorphism are Contact, Regional, and Dynamic metamorphism.
  • Contact Metamorphism occurs when magma comes in contact with an already existing body of rock.

Additional Information

• Sandstone :
  • Sandstone is a sedimentary rock composed of sand-size grains of mineral, rock, or organic material.
    • It also contains a cementing material that binds the sand grains together and may contain a matrix of silt- or clay-size particles that occupy the spaces between the sand grains.
  • Sandstone is a sedimentary rock composed mostly of quartz sand, but it can also contain significant amounts of feldspar, and sometimes silt and clay.
  • Sandstone that contains more than 90% quartz is called quartzose sandstone.

The correct answer is aquifer.

Key Points

• The groundwater stored between layers of hard rock below the water table is called aquifer.
• An aquifer is a saturated zone beneath the water table.
• It is a body of porous rock or sediment saturated with groundwater.
• Groundwater enters an aquifer as precipitation seeps through the soil.
• It can move through the aquifer and resurface through springs and wells.
• There are two general types of aquifers: confined and unconfined.
  • Confined aquifers have a layer of impenetrable rock or clay above them, while unconfined aquifers lie below a permeable layer of soil. 
• Aquifers are typically made up of gravel, sand, sandstone, or fractured rock, like limestone.
• Water can move through these materials because they have large connected spaces that make them permeable.

Additional Information

• Groundwater resources:
  • ​It is the water found underground in the cracks and spaces in soil, sand, and rocks.
  • It is stored in and moves slowly through the geological formation of soil, sand, and rocks called aquifers.
  • The total replenishable groundwater resources in the country are about 432 cubic km.

The correct answer is coffee.

Key Points

• There are over 100 species of the genus Coffee in the world, and all are native to tropical Africa and some Indian Ocean islands.
• Two species, C. arabica and C. canephora, are commonly grown commercially.
  • Coffea canephora is commonly referred to as “robusta” and makes up about 25 to 40% of the coffee grown for consumption.
• Robusta grows in hotter (22 to 26ºC), more humid climates than arabica coffee (18–21ºC), and at lower elevations (from about 200 to 900 m).
• Robusta has a higher caffeine content (30 to 50% more) than arabica.
• Arabica coffee is self-pollinating, robusta requires cross-pollination by insects or wind.

Additional Information

•  Santos port in Brazil is known as "Coffee Port of the world".
• It is located in state of Sao Paulo.

The correct answer is outer core.

Important Points

• The interior of the earth is divided into three parts namely Crust, Mantle, and Core.
• The core is the innermost layer of the earth.
• The radius of the innermost layer(core) is about 3500 km.
• The core is made up of material constituted by nickel and iron.
• The temperature and pressure of the central core are very high.

Key Points

• The core is further subdivided into two layers called the outer core and inner core.
• The outer core of the earth is in a liquid state.
• The inner core is in solid-state
• The outer core is responsible for the earth's magnetic field.

Additional Information

• The crust is the outermost of the earth.
  • It is brittle in nature.
  • it the thinnest layer of Earth.
  • The thickness of the crust varies under the oceanic and continental areas.
• The mantle is the second layer in the interior of the earth.
  • The mantle extends from Moho’s discontinuity to a depth of 2,900 km.
  • The upper portion of the mantle is called the asthenosphere.

The correct answer is 4.

Important Points

• Based on historical seismic activity, the Bureau of Indian Standards has categorized regions in India into four seismic zones: zones II, III, IV and V.
• Of these, the most seismically active area is Zone V and the least active is Zone II. 
• There is a history of devastating earthquakes on the Indian subcontinent.
• The key cause for the high frequency and severity of earthquakes is that the Indian plate is driving into Asia at a rate of roughly 47 mm/year.
• India's geological figures indicate that about 54 percent of the land is prone to earthquakes.
• Research by the World Bank and the United Nations predicts that by 2050, about 200 million urban dwellers in India will be vulnerable to storms and earthquakes.
• The most recent edition of India's seismic zoning map given in India's earthquake-resistant design code [IS 1893 (Part 1) 2002] assigns four degrees of seismicity in terms of zone factors for India.
• In other words, unlike its previous edition, which consisted of five or six zones for the region, India's earthquake zoning map divides India into four seismic zones (Zone 2, 3, 4, and 5).
• According to the new zoning map, the maximum degree of seismicity is predicted in Zone 5, while the lowest level of seismicity is correlated with Zone 2.

Revised earthquake hazard zone map of India

Option 2 is correct, i.e. Aluminium.

Key Points

• Aluminium is the most plentiful (most abundant) of metals in the crust of the earth.
• Aluminium is around 8.1 per cent of the total metals on the surface of the earth.

Important Points

• The most plentiful non-metal in the earth's surface is Oxygen.
• The most plentiful metalloid in the crust of the earth is Silicon.
• O > Si > Al > Fe > Ca are the most abundant elements in the earth crust.

• Block mountains are the type of mountains in which the middle part of the mountain is lower and the parts on both sides are higher. 
• The middle part is known as the rift valley. 
• Black Forest (Germany), Salt Range (Pakistan), Vindhya and Satpura (India) are examples of block mountains. 
• The Ural is a fold mountain. Fold mountains are formed because of folds in the rocks due to the internal movements of the earth. 
• Block mountains - 

The correct answer is L waves.

Key Points

• L waves, or Love waves, are one type of surface wave in seismic activity.
  • Named after British mathematician A.E.H. Love, who first mathematically predicted their existence.
  • Love waves move the ground from side to side in a horizontal plane perpendicular to the direction of propagation.
  • As they travel along the Earth's surface, they cause horizontal shearing and produce entirely horizontal motion.
  • L waves are the slowest of all seismic waves and therefore the last to be recorded by seismographs.
  • These waves are particularly damaging to the foundations of structures due to their horizontal motion.

Additional Information

• P waves:
  • P waves, or Primary waves, are body waves that travel through the interior of the Earth.
  • They are the fastest seismic waves and thus the first to be detected by seismographs.
  • P waves cause particles to move in the same direction as the waves, creating a push-and-pull motion.
• S waves:
  • S waves, or Secondary waves, are also body waves that move through the Earth's interior.
  • They are slower than P waves but faster than surface waves.
  • S waves cause particles to move perpendicular to the wave direction, creating an up-and-down or side-to-side motion.
• R waves:
  • Also known as the Rayleigh wave.
  • It has both compressional and shear motions.
  • These waves result from the interaction of P-waves and vertically polarized S-waves with the surface and can exist in any solid medium.

The correct answer is 30 km.

Key Points

• Earth’s crust:
  • The interior of the earth is made up of several concentric layers which are the crust, the mantle, the outer core and the inner core.
  • The crust is the outermost layer of the earth making up 0.5-1.0% of the earth’s volume and less than 1% of Earth’s mass.
  • Materials that initially stayed in their liquid phase during this process, called “incompatible elements,” ultimately became Earth's brittle crust. 
  • The lower layer of the crust consists of basaltic and ultra-basic rocks.
  • Density increases with depth, and the average density is about 2.7 g/cm3 (the average density of the earth is 5.51 g/cm³).
  • The thickness of the crust varies in the range of 5-30 km in the case of the oceanic crust and 50-70 km in the case of the continental crust.
  • The mean thickness of the oceanic crust is approximately 7 km, while the mean thickness of the continental crust is about 35-40 km.

Important Points

The correct answer is Increases

Key Points

• A rise in temperature with an increase in depth is observed in mines and deep wells.
• These evidence along with molten lava erupted from the earth’s interior supports that the temperature increases towards the centre of the earth.
• While in the upper 100kms, the increase in temperature is at the rate of 120C per km and in the next 300kms, it is 200C per km. But going further deep, this rate reduces to a mere 100C per km.
• It is assumed that the rate of increase in the temperature beneath the surface is decreasing towards the centre.
• Temperature is always increasing from the earth’s surface towards the centre.
• The temperature at the centre is estimated to lie somewhere between 30000C and 50000C, maybe that much higher due to the chemical reactions under high-pressure conditions.

​

The correct answer is Sandstone.

• Sandstone is NOT a metamorphic rock.

Key Points

• Metamorphic rocks are rocks that have become changed by intense heat or pressure while forming.
  • In the very hot and pressured conditions deep inside the Earth's crust, both sedimentary and igneous rocks can be changed into metamorphic rock.
  • ​Metamorphic rock can be formed locally when rock is heated by the intrusion of hot molten rock called magma from the Earth's interior.
    • Some examples of metamorphic rocks are gneiss, slate, marble, schist, and quartzite.
  • Marble, Slate, and quartz are formed after metamorphism. They changed in their original form due to extreme temperatures and pressure.
  • The three types of metamorphism are Contact, Regional, and Dynamic metamorphism.
  • Contact Metamorphism occurs when magma comes in contact with an already existing body of rock.

Additional Information

• Sandstone :
  • Sandstone is a sedimentary rock composed of sand-size grains of mineral, rock, or organic material.
    • It also contains a cementing material that binds the sand grains together and may contain a matrix of silt- or clay-size particles that occupy the spaces between the sand grains.
  • Sandstone is a sedimentary rock composed mostly of quartz sand, but it can also contain significant amounts of feldspar, and sometimes silt and clay.
  • Sandstone that contains more than 90% quartz is called quartzose sandstone.

The correct answer is sedimentary rock.

Important Points

• Sedimentary rocks are formed by deposition, sedimentation, and lithification of sediments over a long period of time.
• Sedimentary rocks may also contain fossils of plants, animals that once lived on them.
• The word ‘sedimentary’ is derived from the Latin word "sedimentum".
• Shale, limestone, and conglomerate are some other examples of sedimentary rocks.

Key Points

• Sandstone is an example of sedimentary rock.
• Sandstone is made from grains of sand.

Additional Information 

• A rock is an aggregate of one or more minerals.
• Igneous rock is formed due to the cooling, solidification, and crystallization of hot and molten magma.
  • Granite, Basalt, Gabbro are examples of Igneous rocks.
• Metamorphic rocks are made up of sedimentary rock and igneous rock which have been subjected to high pressure and temperature.
  • Clay changes into slate and limestone into marble are the examples of metamorphic rocks.
• Marble and quartzite are examples of non-foliated metamorphic rocks.

The correct answer is Tethys Sea.

Important Points

• India is a part of Gondwana land.
• Around 200 million years ago, the large landmass called Panagea started splitting into two large continental masses called Laurasia and Gondwana.
• Gondwana was a supercontinent.
• It existed from the Neoproterozoic period until the Jurassic period.
• Laurasia is a continental mass in the Northern Hemisphere.
• It includes North America, Europe, and Asia except peninsular India.
• The Tethys Sea was an ocean during the Mesozoic era.

Additional Information

• The Black Sea separates Europe and Asia.
• The Red Sea lies between Africa and Arabia.
• The pacific ocean extends from the Arctic Ocean in the North to the Southern Ocean in the South.