Geography · General Awareness

Geology and Earth Structure

1,268 Questions

Geology and Earth Structure explores the physical composition of the planet, including its layers, tectonic plates, and seismic activity. This topic is a core component of geography and general science sections in various competitive exams. Reviewing these concepts builds a solid foundation for answering questions related to natural phenomena.

Layers of the EarthTectonic PlatesEarthquakes and VolcanoesGeomagnetism ApplicationsGeophysical MethodsLandform Formation

Geology and Earth Structure Questions

Multiple choice

The passage says that early instruments for measuring earthquakes were

Directions: Read the following passage and answer the given question.

An earthquake comes like a thief in the night, without warning. It was necessary, therefore, to invent instruments that neither slumbered nor slept. Some devices were quite simple. One, for instance, consisted of rods of various lengths and thicknesses which would stand up on end like ninepins. When a shock came it shook the rigid table upon which these stood. If it were gentle, only the more unstable rods fell. If it were severe, they all fell. Thus, the rods by falling and by the direction in which they fell, recorded for the slumbering scientist, the strength of a shock that was too weak to waken him and the direction from which it came.

But, instruments far more delicate than that were needed if any really serious advance was to be made. The ideal to be aimed at was to devise an instrument that could record with a pen on paper the movements, of the ground or of the table, as the quake passed by. While I write, my pen moves but the paper keeps still. With practice, no doubt, I could, in time, learn to write by holding the pen still while the paper moved. That sounds a silly suggestion, but that was precisely the idea adopted in some of the early instruments (seismometers) for recording earthquake waves. But when table, penholder and paper are all moving, how is it possible to write legibly? The key to a solution of that problem lay in an everyday observation. Why does a person standing in a bus or train tend to fall when a sudden start is made? It is because his feet move on, but his head stays still.

  1. faulty in design

  2. expensive

  3. not sturdy

  4. not sensitive enough
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

"But, instruments far more delicate than that were needed..."

Multiple choice

The early seismometers adopted the idea that in order to record the earthquake, it is

Directions: Read the following passage and answer the given question.

An earthquake comes like a thief in the night, without warning. It was necessary, therefore, to invent instruments that neither slumbered nor slept. Some devices were quite simple. One, for instance, consisted of rods of various lengths and thicknesses which would stand up on end like ninepins. When a shock came it shook the rigid table upon which these stood. If it were gentle, only the more unstable rods fell. If it were severe, they all fell. Thus, the rods by falling and by the direction in which they fell, recorded for the slumbering scientist, the strength of a shock that was too weak to waken him and the direction from which it came.

But, instruments far more delicate than that were needed if any really serious advance was to be made. The ideal to be aimed at was to devise an instrument that could record with a pen on paper the movements, of the ground or of the table, as the quake passed by. While I write, my pen moves but the paper keeps still. With practice, no doubt, I could, in time, learn to write by holding the pen still while the paper moved. That sounds a silly suggestion, but that was precisely the idea adopted in some of the early instruments (seismometers) for recording earthquake waves. But when table, penholder and paper are all moving, how is it possible to write legibly? The key to a solution of that problem lay in an everyday observation. Why does a person standing in a bus or train tend to fall when a sudden start is made? It is because his feet move on, but his head stays still.

  1. the pen that should move just as it moves when we write on paper

  2. the pen that should stay still and the paper should move

  3. both the pen and the paper that should move

  4. neither the pen nor the paper that should move
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

"While I write, my pen moves but the paper keeps still." 

Multiple choice

Why was it necessary to invent instruments to observe an earthquake?

Directions: Read the following passage and answer the given question.

An earthquake comes like a thief in the night, without warning. It was necessary, therefore, to invent instruments that neither slumbered nor slept. Some devices were quite simple. One, for instance, consisted of rods of various lengths and thicknesses which would stand up on end like ninepins. When a shock came it shook the rigid table upon which these stood. If it were gentle, only the more unstable rods fell. If it were severe, they all fell. Thus, the rods by falling and by the direction in which they fell, recorded for the slumbering scientist, the strength of a shock that was too weak to waken him and the direction from which it came.

But, instruments far more delicate than that were needed if any really serious advance was to be made. The ideal to be aimed at was to devise an instrument that could record with a pen on paper the movements, of the ground or of the table, as the quake passed by. While I write, my pen moves but the paper keeps still. With practice, no doubt, I could, in time, learn to write by holding the pen still while the paper moved. That sounds a silly suggestion, but that was precisely the idea adopted in some of the early instruments (seismometers) for recording earthquake waves. But when table, penholder and paper are all moving, how is it possible to write legibly? The key to a solution of that problem lay in an everyday observation. Why does a person standing in a bus or train tend to fall when a sudden start is made? It is because his feet move on, but his head stays still.

  1. Because an earthquake comes like a thief in the night

  2. To make people alert about earthquakes during their conscious as well as unconscious hours

  3. To prove that we are technically advanced

  4. To experiment with the control of man over nature
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

"It was necessary, therefore, to invent instruments that neither slumbered nor slept."

Multiple choice

Which of the following is the area most susceptible to earthquakes?

  1. Himalayan belt

  2. Circum-Pacific belt

  3. Mexican belt

  4. Mediterranean belt
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The Circum-Pacific belt, also known as the Pacific Ring of Fire, is the most earthquake-prone region on Earth. About 90% of the world's earthquakes and 75% of its volcanoes occur along this belt where tectonic plates converge around the Pacific Ocean. While the Himalayan belt and Mediterranean belt are also seismically active, they are not as active as the Pacific Ring of Fire.

Multiple choice

Seismograph is used to record the

  1. temperature of the sun

  2. earthquake shocks

  3. pressure of air at high altitude

  4. accurate time
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A seismograph is a scientific instrument designed to detect and record seismic waves caused by earthquakes, volcanic eruptions, or other ground vibrations. The correct answer is 'earthquake shocks' because that is precisely what seismographs measure - the ground motion produced by seismic events.

Multiple choice

Connard Discontinuity separates

  1. upper continental crust from the lower one

  2. crust from the mantle

  3. upper mantle from the lower one

  4. outer core from the inner core
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Conrad Discontinuity (named after S. Connard) is a boundary within the continental crust that separates the upper continental crust (felsic, granitic rocks) from the lower continental crust (more mafic rocks). It occurs at depths of 15-20 km and is detected by seismic velocity changes. The Mohorovicic discontinuity separates crust from mantle, Gutenberg separates mantle from core, and the core-mantle boundary separates outer core from inner core.

Multiple choice

Which of the following factors leads to the movement of earth's crustal plates?

  1. Variation in pressure in different layers of the earth's interior.

  2. Radioactive decay in the core of the earth.

  3. Convectional current that occurs in the crust.

  4. The earth's interior.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This is a tricky question. Most of the students may wrongly mark option 3 as their answer, but it should be noted that convectional currents occur in the mantle, and not in the crust.

The movement of the earth's crustal plates is believed to be due to convection currents which occur in the semi-molten mantle. These convection currents are created by heat from within the earth - much of which is generated by radioactive decay in the core. 

Multiple choice

Which of the following statements is true about the interior of the earth?

  1. Crust forms the largest fraction of the earth’s volume.

  2. Mantle forms the largest fraction of the earth’s volume.

  3. Core forms the largest fraction of the earth’s volume.

  4. Mantle and core form about 80 percent of the earth’s volume.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The planet Earth is made up of three main shells: very thin and brittle crust, mantle and core. Mantle and core are each divided into two parts. Although core and mantle are equal in thickness, core actually forms only 15 percent of the earth's volume, whereas mantle occupies 84 percent. The crust makes up the remaining 1 percent.

Multiple choice

A rift valley is a linear-shaped lowland between highlands or mountain ranges created by the action of a geologic rift or fault, which is subsequently further deepened by the forces of erosion. In this context, which of the following statements is/are true?

  1. World's largest fresh water lakes are typically rift valleys.
  2. The most extensive rift valley is located along the crest of the mid-ocean ridge system and is the result of sea floor spreading.

  1. Only 1

  2. Only 2

  3. Both 1 and 2

  4. Neither 1 nor 2
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A rift valley is linear-shaped lowland between highlands or mountain ranges created by the action of a geologic rift or fault. This action is manifest as crustal extension, a spreading apart of the surface which is subsequently further deepened by the forces of erosion. When the tensional forces are strong enough to cause the plate to split apart, it will do so such that a center block will drop down relative to its flanking blocks. The largest freshwater lakes in the world are all located in rift valleys. The most extensive rift valley is located along the crest of the mid-ocean ridge system and is the result of sea floor spreading. Examples of this type of rift include the Mid-Atlantic Ridge and the East Pacific Rise. 

Multiple choice

Which of the following is related to the origin of the earth?

  1. Thermal-convection Hypothesis

  2. Tetrahedral Hypothesis

  3. Planetesimal Hypothesis

  4. Drift Hypothesis
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Planetesimal Hypothesis (Chamberlin and Moulton, 1905) proposes that planets formed from small solid bodies called planetesimals, which were created from material pulled from the sun by a passing star. This is a theory about Earth's origin. The other options: Thermal-convection relates to mantle dynamics, Tetrahedral is about Earth's shape, and Drift relates to continental movement, not origin.

Multiple choice

Which of these is an earthquake that occurs before a larger seismic event?

  1. Earthquake storm

  2. Earthquake swarms

  3. Foreshock

  4. Remotely triggered earthquakes

  5. Shear wave splitting
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A foreshock is an earthquake that occurs before a larger seismic event (the main shock) and is related to it in both time and space. The designation of an earthquake as fore shock, main shock or after shock is only possible after the event.