PGP MCQs Day-1 (Geography)

Answer: C

Explanation:

Statement 1 and 2 are correct:

• • As per the plate tectonic theory, the surface of the earth and the interior are not static and motionless but are dynamic. The mobile rock beneath the rigid plates is believed to be moving circularly. The heated material rises to the surface, spreads, and begins to cool, and then sinks backs into deeper depths. This cycle is repeated over and over to generate what scientists call a convictive flow. Heat within the earth comes from two main sources: radioactive decay and residual heat.

Answer: D

Explanation:

• • Composite volcano is conical with a concave shape that is steeper near the top. These mountains commonly have snow-covered peaks standing high above the surrounding mountainous terrain. Composite volcanoes are large volcanoes (many thousands of feet or meters tall) generally composed of lava flows, pyroclastic deposits, and mudflow (lahar) deposits, as well as lava domes. Composite volcanoes are active over long periods (tens to hundreds of thousands of years) and erupt periodically. Example: Mount Rainier is an active volcano and the tallest peak in the Pacific Northwest.
  • Caldera – large depression formed when a volcano erupts and collapses. Example: Crater Lake in Oregon.
  • Mid Ocean ridge volcanoes is a seafloor mountain system formed by plate tectonics, typically has a depth of about 2,600 meters and rises about 2,000 meters above the deepest portion of an ocean basin. Examples: The Mid-Indian Ocean Ridge, Carlsberg Ridge, Pacific-Antarctic Ridge, and the East Pacific Rise.
  • A shield volcano is a type of volcano named for its low profile, resembling a warrior shield lying on the ground, highly fluid lava. Examples: Mauna Kea and Mauna Loa.

Answer: B

Explanation:

Types of Earthquakes

• • The most common ones are the tectonic earthquakes. These are generated due to sliding of rocks along a fault plane.
  • A special class of tectonic earthquakes is sometimes recognized as volcanic earthquakes. However, these are confined to areas of active volcanoes.
  • In the areas of intense mining activity, sometimes the roofs of underground mines collapse causing minor tremors. These are called collapse earthquakes.
  • Ground shaking may also occur due to the explosion of chemical or nuclear devices. Such tremors are called explosion earthquakes.
  • The earthquakes that occur in the areas of large reservoirs are referred to as reservoir induced earthquakes.

Answer: C

Explanation:

• • The terrestrial planets were formed in the close vicinity of the parent star where it was too warm for gases to condense to solid particles.
  • The solar wind was most intense nearer the sun; so, it blew off lots of gas and dust from the terrestrial planets.
  • The terrestrial planets are smaller, and their lower gravity could not hold the escaping gases.

Answer: D

Explanation:

• • Big Bang theory is also called the expanding universe hypothesis. Edwin Hubble, in 1920, provided evidence that the universe is expanding. As time passes, galaxies move further and further apart.
  • Space between the galaxies is increasing, but does not support the expansion of galaxies.
  • Primordial elements -hydrogen, helium and lithium – condense through gravity that formed early stars and galaxies.

Answer: A

Explanation:

• • Countries having large longitudinal spread can adopt several time zones. Like Russia, which extends through almost 165-degree of latitude, it is divided into 11 time zones. Similarly, the USA and Canada are divided into 5 time zones.
  • Countries with large latitudinal spread but limited longitudinal spread may adopt single time zones. Like India, which spread across almost 300-degree latitudes has adopted a single time zone. It has adopted 82.50 east for the standard time which is 5 hours and 30 minutes ahead of Greenwich meantime.
  • A country with very small latitudinal or longitudinal expense may have large altitudinal variation.
  • Location of a country with respect to the equator does not have any correlation with adoption of multiple time zones. One country in the arctic zone may adopt a single time zone if its longitudinal spread is small.

Answer: C

Explanation:

Residual mountains are the remnants of previously existing mountains that have been subjected to weathering and erosion for an extended period. The residual mountains owe their current shape to erosion by rivers, glaciers, wind, etc. Example: Girnar hills, Nilgiri hills, and Sierra of Spain.

• • All mountains of the peninsula with the exception of the Aravallis are relict mountains.
  • They form those portions of old plateau which have escaped weathering. The residual mountains stand alone in the surroundings area reduced in height. They may be part of an upland eroded to form a number of hills.

Answer: A

Explanation:

• • The ‘Big Splat Event’ states that an object the size of mars collided with the early earth to create the moon.

Answer: D

Explanation:

Intrusive landforms are formed when magma cools down within the crust.

• • Intrusive features like batholith stocks, lapoliths, laccoliths, sills and dykes are formed. Its conduits are implied after an eruption they can collapse in the formation of caldera or remain as lava tubes and caves. The mass of cooling magma is called pluton and rock around is known as country rock.

Answer: D

Explanation:

• • The rocks equidistant on either side of the crest of mid-oceanic ridges show remarkable similarities in terms of period of formation, chemical compositions and magnetic properties.
  • Rocks closer to the mid-oceanic ridges have normal polarity and are the youngest. The age of the rocks increases as one moves away from the crest.
  • The ocean crust rocks are much younger than the continental rocks. The age of rocks in the oceanic crust is nowhere more than 200 million years old.
  • The sediments on the ocean floor are unexpectedly very thin. Scientists were expecting, if the ocean floors were as old as the continent.
  • The deep trenches have deep-seated earthquake occurrences while in the mid oceanic ridge areas, the quake foci have shallow depths.

Answer: B

Explanation:

• • Continental crust is mostly composed of different types of granites also referred to as SIAL (Silicon and Aluminum).
  • Oceanic crust is made up of SIMA (Silicon and Magnesium).
  • Mantle is made of silicon – a wide variety of compounds that share silicon and ocean structure and composition of over 50% of olivine and high pressure – Mg rich olivine. Therefore, the third pair is correct.
  • Core is made almost entirely of metal – specifically iron and nickel alloy is simply the element ‘chemical’ – NiFe. Therefore, the fourth pair is correct.

Answer: A

Explanation:

• • Mining drilling and volcanic eruptions are examples of direct sources. During the process of mining and drilling rocks and minerals are extracted which gives information that there is a layer system in the crust.
  • Volcanic eruption suggests that there is the same zone inside the earth which is very hot and liquid.
  • Seismic waves, gravitational fields, magnetic fields, falling meteors etc. are examples of indirect sources.

They are very important for knowing about the earth’ interior.

Answer: A

Explanation:

Refer to the image given below:

Answer: C

Explanation:

• • Igneous rocks form out of magma and lava from the interior of the earth, they are known as primary rocks.
  • Igneous rocks are classified based on texture. Texture depends upon size and arrangement of grains or other physical conditions of the materials.
  • Molten material is cooled slowly at great depths, mineral grains may be very large.
  • Granite, gabbro, pegmatite, basalt, volcanic breccia and tuff are some of the examples of igneous rocks.
  • Generally, rocks get metamorphosed when the crystal in the original rock gets recrystallized, hence option 1 is incorrect.

Answer: D

Explanation:

• • Nebular hypothesis – was first published by Immanuel Kant ‘Universal Natural History and Theory of Heavens’ (1755) and then modified by Pierre Laplace (1796).
  • He assumed that there was a massive and hot gaseous nebula somewhere in space. As a result of this assumption, he was able to address the nebula heat problem.
  • The massive and hot nebula was rotating or spinning on its own axis from the beginning, slowly reducing the heat.

Answer: B

Explanation:

Refer to the image given below:

Answer: B

Explanation:

• • There are two types of body waves. They are called P and S-waves.
  • P-waves move faster and are the first to arrive at the surface. These are also called ’primary waves’. The P-waves are similar to sound waves. They travel through gaseous, liquid, and solid materials.
  • S-waves arrive at the surface with some time lag.
  • S-waves are also called secondary waves. They can travel only through solid materials. This characteristic of S-waves helped scientists to understand the structure of the interior of the earth.

Answer: C

Explanation:

• • It was proposed by Alfred Wegner, hence statement 1 is incorrect.
  • According to continental drift theory there was one big landmass which he called Pangea, and which was covered by one big ocean called Panthalassa, hence statement 2 is correct.
  • He had given pole-fleeing force (due to centrifugal force caused by earth’s rotation) and buoyancy force (ship floats in water due to buoyant force offered by water) but later found that they were inadequate to explain the movement of continents.

Answer: C

Explanation:

• • Tropical cyclones are known with different names: typhons, tropical storm, cyclonic storm, hurricane and tropical depression.
  • A source of warm, moist air drives from tropical oceans with the surface temperature normally in the region of, or in excess, of 27⁰
  • The eye of the cyclones is a region of calm and subsiding air.
  • Tropical cyclones do not form over the equator because the Coriolis force is zero at the equator. Even though the equator is a zone of wind convergence, it has nothing to do with tropical cyclones as such.
  • The Coriolis effect made by the earth rotation causes the wind to rotate and warm air rises quickly.

Answer: B

Explanation:

• • Sections of plate boundaries that have not ruptured in the recent past.
  • A seismic gap is a segment of an active fault known to produce significant earthquakes that has not slipped in an unusually long time, compared with other segments along the same structure.
  • It is known that there are numbers of “seismic gaps” in the Himalaya with a potential to slip and produce greater than 7.5 magnitude earthquakes.

Answer: D

Explanation:

Option D is correct.

Olivine is the name of a group of rock-forming minerals that are typically found in mafic and ultramafic igneous rocks such as basalt, gabbro, dunite, diabase, and peridotite. Most olivine found at Earth’s surface is in dark-colored igneous rocks. It usually crystallizes in the presence of plagioclase and pyroxene to form gabbro or basalt. These types of rocks are most common at divergent plate boundaries and at hot spots within the centers of tectonic plates. Olivine has a very high crystallization temperature compared to other minerals. That makes it one of the first minerals to crystallize from a magma. Magnesium, iron and silica are major elements of olivine. It is used in jewellery. It is usually a greenish crystal, often found in basaltic rocks.

Answer: B

Explanation:

• • From the surface of the earth towards the centre, density of rocks, temperature and pressure increases.

Answer: C

Explanation:

Quartz is one of the important components of sand and granite. It consists of silica. It is a hard mineral virtually insoluble in water. It is white or colourless and used in radio and radar. It is also one of the most important components of granite.

Answer: D

Explanation:

Types of earthquake:

1. The most common ones are the tectonic earthquakes. These are generated due to sliding of rocks along a fault plane.

2. A special class of tectonic earthquakes is sometimes recognised as volcanic earthquakes. However, these are confined to areas of active volcanoes.

3. In the areas of intense mining activity, sometimes the roofs of underground mines collapse causing minor tremors. These are called collapse earthquakes.

4. Ground shaking may also occur due to the explosion of chemical or nuclear devices. Such tremors are called explosion earthquakes.

5. The earthquakes that occur in the areas of large reservoirs are referred to as reservoir induced earthquakes.

Answer: C

Explanation: Sedimentary rocks are formed from sediment accumulated over long periods, usually underwater. They are distinguished from the other rock types in their characteristic layer formation and are termed stratified rocks.

• • Examples of metamorphic rocks: Gneissoid, granite, syenite, slate, schist, marble, quartzite.
  • Examples of Igneous rocks: Granite, gabbro, pegmatite, basalt, volcanic breccia and tuff.
  • Examples of sedimentary rocks: (i) mechanically formed — sandstone, conglomerate, limestone, shale, loess etc. are examples; (ii) organically formed — geyserite, chalk, limestone, coal etc. are some examples; (iii) chemically formed —chert, limestone, halite, potash.

Answer: A

Explanation:

• • The earthquake events are scaled either according to the magnitude or intensity of the shock. The magnitude scale is known as the Richter scale. The magnitude relates to the energy released during the quake. The magnitude is expressed in numbers, 0-10. The intensity scale is named after Mercalli, an Italian seismologist. The intensity scale takes into account the visible damage caused by the event. The range of intensity scale is from 1-12.
  • If a high magnitude earthquake happens in a place where there is no human habitation, there will be very less or no loss to human life and property. Therefore, such earthquakes will have higher value on the Richter scale but low value on Mercalli scale.

Answer: C

Explanation:

Please refer to the table given below:

Answer: B

Explanation:

Refer to the table of most abundant elements in the Earth’s Crust given below:

Answer: C

Explanation:

• • Statement 1 is correct: Rocks closer to the Mid-oceanic ridge are younger. The age of the rocks increases as one moves away from the crest of the ridge.
  • Statement 2 is correct: Rocks closer to the Mid-oceanic ridge have normal polarity.
  • Statement 3 is incorrect: Ocean crust rocks are younger than continental rocks. The age of rocks in the oceanic crust is nowhere more than 200 million years old. Some of the continental rock formations are as old as 3,200 million years.
  • Statement 4 is correct: Oceanic crust is thinner as compared to the continental crust. The mean thickness of oceanic crust is 5 km whereas that of the continental is around 30 km. The continental crust is thicker in the areas of major mountain systems. It is as much as 70 km thick in the Himalayan region.

Answer: B

Explanation:

Statement 1 is incorrect: Igneous, Sedimentary and metamorphic rocks when exposed to denudational agents are broken up into various sizes of fragments. Such fragments when transported by various exogenous agencies and deposited forms the sedimentary rocks in a process called Lithification.

Statement 2 is correct: In many sedimentary rocks, the layers of deposits retain their characteristics even after lithification which we can observe in the layers of varying thickness in the sedimentary rocks like sandstone, shale etc.

Answer: B

Explanation:

Please refer to the table given below:

Answer: A

Explanation:

The word metamorphic means ‘change of form’. These rocks form under the action of pressure, volume and temperature (PVT) changes. Metamorphism occurs when rocks are forced down to lower levels by tectonic processes or when molten magma rising through the crust comes in contact with the crustal rocks or the underlying rocks are subjected to great amounts of pressure by overlying rocks. (Hence, statement 2 is incorrect).

Metamorphism is a process by which already consolidated rocks undergo recrystallisation and reorganisation of materials within original rocks (Hence, statement 1 is correct).

Mechanical disruption and reorganization of the original minerals within rocks due to breaking and crushing without any appreciable chemical changes is called dynamic metamorphism. (Hence, statement 3 is incorrect). The materials of rocks chemically alter and recrystallise due to thermal metamorphism.

Answer: A

Explanation:

• • The Appalachians first formed roughly 480 million years ago during the Ordovician Period.
  • Continental collisions gave rise to the Urals between 250 and 300 million years ago.
  • The Rocky Mountains were created during the Laramide orogeny, a period of mountain building which started 80 million years ago, and ended 50 million years ago.
  • Himalayas are formed in the Tertiary period. Indian plate collided with Asian plate about 40-50 million years ago causing rapid uplift of the Himalayas.

Answer: B

Explanation:

All processes that move, elevate or build up portions of the earth’s crust come under diastrophism. Diastrophism and Volcanism are the endogenic geomorphic processes (Hence statement 1 is correct). Diastrophism include: (i) orogenic processes involving mountain building through severe folding and affecting long and narrow belts of the earth’s crust; (ii) epeirogenic processes involving uplift or warping of large parts of the earth’s crust; (iii) earthquakes involving local relatively minor movements; (iv) plate tectonics involving horizontal movements of crustal plates. (Hence statement 2 is correct).

In the process of orogeny, the crust is severely deformed into folds. Due to epeirogeny, there may be simple deformation. Orogeny is a mountain building process whereas epeirogeny is continental building process. Through the processes of orogeny, epeirogeny, earthquakes and plate tectonics, there can be faulting and fracturing of the crust. All these processes cause pressure, volume and temperature (PVT) changes which in turn induce metamorphism of rocks. (Hence statement 3 is incorrect).

Answer: C

Explanation:

• • The entire zone beyond 103° does not receive S-waves, and hence this zone is identified as the shadow zone of S-waves. This observation led to the discovery of the liquid outer core. However, the seismographs located beyond 142° from the epicenter, record the arrival of P-waves, but not that of S-waves. This gives clues about the solid inner core.

Answer: A

Explanation:

• • The forces responsible for movement of land masses given by theory were inadequate.
  • The evidence in support of the theory was not fool
  • The idea that continental crust floats freely over oceanic crust was proved wrong by Plate Tectonic theory.
  • The idea of horizontal movement of land masses was carried forward and retained by Plate Tectonic Theory which provides satisfactory answers to almost all questions related to past and present day distributions of oceans and continents.

Answer: C

Explanation:

• • Cocos plate – Between Central America and Pacific Plate
  • Nazca plate – Between South America and Pacific Plate
  • Philippines plate – Between Asiatic and Pacific Plate

Answer: D

Explanation:

• • Exfoliation domes and tors result due to unloading and thermal expansion respectively.

Answer: C

Explanation:

Mountains may be classified as:

• • Fold mountains like the Himalayas, the Rockies, the Andes.
  • Block mountains like Vosges mountains in France, the Black Forest in Germany, Vindhya and Satpura in India.
  • Volcanic mountains like Cascade Range in the USA, Mount Kenya, Mount Kilimanjaro, Mount Fujiyama.

Note: Earthquakes do not result in mountains, although it can change the nature of landscape.

Answer: A

Explanation:

• • In geology, a nappe or thrust sheet is a large sheetlike body of rock that has been moved more than 2 km or 5 km above a thrust fault from its original position. Nappes form in compressional tectonic settings like continental collision zones or on the overriding plate in active subduction zones.
  • In the Himalayas, over folds and recumbent folds are often found detached from their roots and carried a few hundred kilometres away by the tectonic forces. These detached folds are called ‘nappe.’

Answer: A

Explanation:

Basaltic Magma flows out along the divergent plate boundary. It has less silica, and hence it is less viscous. It flows over a long-distance causing seafloor spreading but not volcanic islands.

While, andesitic or acidic magma flows out along the convergent boundary. Andesitic or acidic magma has more silica content, and hence it has higher viscosity. It doesn’t move quickly and also solidifies faster. This helps in building a layer over layer on a confined region giving rise to a volcanic mountain.

Answer: C

Explanation:

• • Mount Stromboli – Composite volcano
  • Hawaiian volcano – Shield volcano
  • Deccan traps – Flood Basalt volcano

Answer: D

Explanation:

Hotspot volcanism is a type of volcanism that typically occurs at the interior parts of the lithospheric plates. E.g. Hawaiian Hotspot, the Yellowstone Hotspot, the Reunion Hotspot.

• • Plate Tectonic Theory failed to satisfactorily explain Hotspot volcanism. Statement 1 is not correct.
  • A mantle plume is convection of abnormally hot rock (magma) within the Earth’s mantle. Mantle plumes are formed at the core-mantle boundary where an abnormally hot plume of rock accumulates. Statement 2 is not correct.
  • The mantle plume provides a continuous supply of abnormally hot magma to a fixed location in the mantle referred to as a hotspot.
  • A huge eruption of this Reunion hotspot 66 million years ago is thought to have formed the Deccan Traps. Statement 3 is correct.

Answer: A

Explanation:

Tsunami waves are not noticed by ships far out at sea because their amplitude is negligible when compared with their wavelength, and hence the waves go unnoticed in deep oceans. When tsunamis approach shallow water, the wave amplitude increases.

Answer: D

Explanation:

The following are the immediate hazardous effects of earthquake:

• • Ground Shaking
  • Differential ground settlement
  • Land and mudslides
  • Soil liquefaction
  • Ground lurching
  • Avalanches
  • Ground displacement
  • Floods from dam and levee failures
  • Fires
  • Structural collapse
  • Falling objects
  • Tsunami

Answer: A

Explanation:

Statement 1 is incorrect: Shallow focus earthquakes are located along divergent plate boundaries. Deep focus earthquakes are located along the convergent plate boundaries.

Statement 2 is correct: Shallow focus earthquakes are common all along the mid-oceanic ridge.

Statement 3 is correct: Shallow focus earthquakes are more damaging than deep focus earthquakes. Seismic waves from deep quakes have to travel farther to the surface, losing energy along the way.

Answer: B

Explanation:

Answer: D

Explanation:

The crust forms only 1 per cent of the volume of the earth, 84 per cent consists of the mantle and 15 per cent makes the core.

Answer: A

Explanation:

Andesitic/Acidic lava:

• • Highly viscous with a high melting point.
  • Light-coloured, low density and high percentage of silica.
  • Flow slowly and seldom travel far before solidifying. Therefore, the resultant volcanic cone is stratified (hence the name stratovolcano) and steep-sided.
  • Occurs mostly along the destructive plate boundaries.

Basaltic/Basic lava:

• • Hottest of all lavas and are highly fluid.
  • Dark coloured basalt, rich in iron and magnesium but poor in silica.
  • Flow out of volcanic vents quietly and are not very explosive.
  • Affect extensive areas, spreading out as thin sheets over great distances before they solidify.
  • Common along the constructive plate boundaries.

Answer: D

Explanation:

The Earth is wider at the equator than from pole to pole, mainly because the centrifugal forces of its rotation make it bulge outwards.