Test: Geography - 1 - UPSC MCQ

• 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 in a circular manner.

  • The heated material rises to the surface, spreads and begins to cool, and then sinks back into deeper depths. This cycle is repeated over and over to generate what scientists call a convection cell or convective flow. Heat within the Earth comes from two main sources: radioactive decay and residual heat.

  • The radioactive decay of naturally occurring chemical elements - most notably uranium, thorium, and potassium - releases energy in the form of heat, which slowly migrates toward the Earth's surface. Residual heat is gravitational energy left over from the formation of the Earth - 4.6 billion years ago - by the "falling together" and compression of cosmic debris.

This is a typical confusing question that is based upon a simple paragraph as follows- The primary criteria for selection of sites for Biosphere Reserves as laid down in the Guidelines issued by the Government are ,a site that must contain an effectively protected and minimally disturbed core area of value of nature conservation and should include additional land and water suitable for research and demonstration of sustainable methods of research and management and the core area should be typical of a biogeographical unit and large enough to sustain viable populations representing all trophic levels in the ecosystem. The secondary criteria are areas having rare and endangered species, areas having diversity of soil and micro-climatic conditions and indigenous varieties of biota and areas potential for preservation of traditional tribal or rural modes of living for harmonious use of environment.

o There are two rain-bearing systems in India.

• First originates in the Bay of Bengal causing rainfall over the plains of north India.

• Second is the Arabian Sea current of the southwest monsoon which brings rain to the west coast of India.

The flow of water through well-defined channels is known as 'drainage' and the network of such channels is called a 'drainage system'.

1. The drainage pattern of an area is the outcome of the geological time period, nature and structure of rocks, topography, slope, amount of water flowing and the periodicity of the flow. Hence, all the options are correct.
2. Some of the different types of drainage patterns are:
   • Dendritic: The drainage pattern resembling the branches of a tree is known as Dendritic. It is formed in areas of gently sloping land. Himalayan rivers follow Dendritic pattern
   • Radial: When the rivers originate from a hill and flow in all directions, the drainage pattern is known as Radial. The rivers originating from the Amarkantak range present a good example of it.
   • Trellis: When the primary tributaries of rivers flow parallel to each other and secondary tributaries join them at right angles, the pattern is known as Trellis. Rivers in the upper part of the Himalayan region form a trellis pattern
   • Centripetal: When the rivers discharge their waters from all directions in a lake or depression, the pattern is known as Centripetal pattern. For example, Loktak

• Statement 1 is correct: When the Earth’s crust bends folding occurs, but when it cracks, faulting takes place. Block mountains are created when large areas or blocks of Earth are broken and displaced vertically.

Rift Vallc\

Escarpment

• Fault-block mountains are formed by the movement of large crustal blocks when forces in the Earth’s crust pull it apart (Tension), bedrock is split into two parts by tectonic activity. The faulted edges are very steep.

Block Mountains are formed when two tectonic plates move away from each other causing cracks on the surface of the Earth. When parallel cracks or faults occur, the strip of land or the block of land between them may be raised resulting in the formation of block mountains.Examples, Black forest and the Vosges of Rhineland.

• lock mountains are also formed when the crust of the Earth sinks (Compression) on both sides of two parallel faults. Therefore, a block mountain can be found between two rift valleys. The land which sinks is known as graben. Examples, East African rift valleys.
• Statement 2 is not correct: The Vosges and the Black Forest of the Rhineland, Great African Rift Valley system are the best examples.Mt. Monadnock in U.S.A is an example of a residual mountain.

compression

Horst Graben

Block mountains are also called fault block mountains since they are formed due to faulting as a result of tensile and compressive forces. Block mountains are surrounded by faults on either side of rift valleys or grabens. The uplifted blocks are termed as horsts and the lowered blocks are called graben

Panda is there in the logo of World Wildlife fund. The inspiration for the WWF logo came from Chi-Chi, a giant panda that was living at the London Zoo in 1961,which is the same year WWF was created. WWF’s founders wanted a strong, recognizable symbol that would overcome all language barriers.

Bars, Barriers and Spits are depositional landforms formed by the action of waves and currents.

o A ridge of sand and shingle formed in the sea in the off-shore zone (from the position of low tide waterline to seaward) lying approximately parallel to the coast is called an off-shore bar.

o An off-shore bar which is exposed due to further addition of sand is termed a barrier bar. The off-shore bars and barriers commonly form across the mouth of a river or at the entrance of a bay. Sometimes such barrier bars get keyed up to one end of the bay when they are called spits. Spits may also develop attached to headlands/hills.

o The barriers, bars and spits at the mouth of the bay gradually extend leaving only a small opening of the bay into the sea and the bay will eventually develop into a lagoon. The lagoons get filled up gradually by sediment coming from the land or from the beach itself (aided by wind) and a broad and wide coastal plain may develop replacing a lagoon.

Statements 1 and 2 are correct : Two major island groups in India are present in the Bay of Bengal and the other in the Arabian Sea. The Bay of Bengal island groups consist of about 572 islands/islets. These are situated roughly between 6°N-14°N and 92°E -94°E. The two principal groups of islets include the Ritchie's archipelago and the Labyrinth island.

A characteristic feature of rainfall in India is its variability. The variability of rainfall is computed with the help of the following formula:

C.V. = Standard Deviation x 100/ Mean; where C.V. is the coefficient of variation, o The values of coefficient of variation show the change from the mean values of rainfall. The actual rainfall in some places deviates from 20-50 per cent. The values of coefficient of variation show variability of rainfall in India.

o A variability of less than 25 per cent exists on the western coasts, Western Ghats,

northeastern Peninsula, eastern plains of the Ganga, northeastern India, Uttarakhand and Himachal Pradesh and south-western part of Jammu and Kashmir. These areas have an annual rainfall of over 100 cm.

o A variability of over 50 per cent exists in the western part of Rajasthan, northern part of Jammu and Kashmir and interior parts of the Deccan plateau. These areas have an annual rainfall of less than 50 cm. o Rest of India (including Punjab plains) has a variability of 25-50 per cent and these areas receive an annual rainfall between 50-100 cm. Hence the correct answer is option (b).

• The retreating southwest monsoon season is marked by clear skies and rise in temperature. The land is still moist. Owing to the conditions of high temperature and humidity, the weather becomes rather oppressive. This is commonly known as the "October heat'. Hence option (b) is the correct answer

• In the second half of October, the mercury begins to fall rapidly, particularly in northern India. The weather in the retreating monsoon is dry in north India but it is associated with rain in the eastern part of the Peninsula. Here, October and November are the rainiest months of the year.

• Hydrological Drought: It results when the availability of water in different storages and reservoirs like aquifers, lakes, reservoirs, etc. falls below what the precipitation can replenish. Hence option (b) is the correct answer.

• Meteorological Drought: It is a situation when there is a prolonged period of inadequate rainfall marked with mal-distribution of the same over time and space.

• Agricultural Drought: It is also known as soil moisture drought, characterised by low soil moisture that is necessary to support the crops, thereby resulting in crop failures. Moreover, if an area has more than 30 per cent of its gross cropped area under irrigation, the area is excluded from the drought-prone category.

• Ecological Drought: When the productivity of a natural ecosystem fails due to the shortage of water and as a consequence of ecological distress, damages are induced in the ecosystem.

• Geological time is an important metric for analysis events. The period is the basic unit of geological time in which a single type of rock system is formed. Two or more periods comprise a geological Era. Two or more Eras form an Eon, the largest division of geologic time. Some periods are divided into epochs.

• The descending sequence from Eon to Age is – Eon > Era > Period > Epoch > Age. Hence option (a) is the correct answer.

• Recently, three more ages have been added by the scientists to the Holocene epoch. The Holocene epoch commenced 11,700 years ago after the end of the last ice age. Since that time, the Earth’s Climate has continued to fluctuate.

• First, there was a warm period that lasted from 11,700 to about 8,300 years ago. Scientists have named this age the Greenlandian age. Next, the Earth went through a gradual cooling period from about 8,300 to 4,200 years ago, and this is now known as the Northgrippian age. The last age of the Holocene began 4,200 years ago during a worldwide megadrought, and it has been named the Meghalayan age.

Dissected plateaus are formed as a consequence of the continual process of weathering and erosion by running water and winds where high and extensive plateaus are gradually worn down, and their surfaces made irregular.

In drier countries, vertical corrasion by rivers and abrasion by winds will dissect the plateau into steep - sided tabular masses which are termed as Mesas and Buttes, intersected by deep canyons. Buttes were once part of flat, elevated areas of land known as mesas or plateaus. In fact, the only difference between a mesa and a butte is its size. Most geographers say a butte is taller than it is wide, while a mesa is a much larger, slightly less elevated feature. This is a common feature of arid and semi-arid areas. For e.g. In the South-Western USA. Hence, option (a) is the correct answer.

There are three main reasons for the excessive cold in north India during the winter season :

• Continentality- States like Punjab, Haryana and Rajasthan being far away from the moderating influence of sea experience continental Climate.

• The snowfall in the nearby Himalayan ranges creates a cold wave situation.

• Around February, the cold winds coming from the Caspian Sea and Turkmenistan bring cold wave along with frost and fog over the northwestern parts of India.

• The easterly jet stream sets in along 15°N latitude only after the western jet stream has withdrawn itself from the region,i.e.around June. This easterly jet stream is held responsible for the burst of the monsoon in India. It does not play a role in an extremely cold climate in North India during the winter season.

Hence, all the options are correct.

o Cumulus: This is a vertical cloud with a rounded top and horizontal base, typical of humid tropical regions, associated with up-rising convectional currents. Its great white globular masses may look grey against the sun but it is a fair-weather cloud. Hence, option (b) is correct.

o Cirrus: This looks fibrous and appears like wisps in the blue sky; it is often called' mares'tails'. It indicates fair weather and often gives a brilliant sunset.

o Nimbostratus: This is a dark, dull cloud, clearly layered, and is also known as a 'rain cloud', It brings continuous rain, snow or sleet.

o Cumulonimbus: This is, in fact, an overgrown cumulus cloud, extending for a tremendous vertical height from a base of 2,000 feet to over 30,000 feet. Its black and white globular masses take a fantastic range of shapes. Its cauliflower top often spreads out like an anvil. This is frequently seen in tropical afternoons. It is also referred to as a 'thunder-cloud' and brings convectional rain, accompanied by lightning and thunder.

Statement 1 is not correct: Igneous rocks form out of magma and lava from the Earth's interior and known as primary rocks. The igneous rocks are formed when magma cools and solidifies. When magma in its upward movement cools and turns into the solid form it is called igneous rock. The process of cooling and solidification can happen in the ear th's crust or on the surface of the Earth.

o Statement 2 is correct: Igneous rocks are classified based on texture. The texture depends upon the size and arrangement of grains or other physical conditions of the materials. If molten material is cooled slowly at great depths, mineral grains may be very large. Sudden cooling (at the surface) results in small and smooth grains. Intermediate conditions of cooling would result in intermediate sizes of grains making up igneous rocks.

o Statement 3 is correct: Granite, gabbro, pegmatite, basalt, volcanic breccia and tuff are some of the examples of igneous rocks.

o In our country, debris avalanches and landslides occur very frequently in the Himalayas. There are many reasons for this. One, the Himalayas are tectonically active. They are mostly made up of sedimentary rocks and unconsolidated and semi-consolidated deposits. The slopes are very steep.

o Compared to the Himalayas, the Nilgiris bordering Tamil Nadu, Karnataka, Kerala and the Western Ghats along the west coast are relatively tectonically stable and are mostly made up of very hard rocks; but, still, debris avalanches and landslides occur though not as frequently as in the Himalayas, in these hills because.

• Many slopes are steeper with almost vertical cliffs and escarpments in the Western Ghats and Nilgiris.

• Mechanical weathering due to temperature changes and ranges is pronounced.

• They receive heavy amounts of rainfall over short periods.

o So, there is almost direct rock fall quite frequently in these places along with landslides and debris avalanches.

o Comparison between the Himalayan and the Peninsular Rivers:

• Himalayan rivers originate from the lofty Himalayan ranges while Peninsular Rivers originate in the Peninsular Plateau.

• Himalayan rivers have large basins and catchment areas while Peninsular rivers have small basins and catchment areas.

• Himalayan rivers flow through deep V-shaped valleys called gorges. These gorges have been carved out by down cutting carried on side by side with the uplift of the Himalayas. While the Peninsular rivers flow in comparatively shallow valleys. These are more or less completely graded valleys. The rivers have little erosional activity to perform.

• The Himalayan rivers are perennial in nature, i.e., water flows throughout the year in these rivers. These rivers receive water both from the monsoons and snow-melt. The Peninsular rivers receive water only from rainfall and water flows in these rivers in rainy season only. Therefore, these rivers are seasonal or non-perennial. Hence, statement 1 is correct.

• Himalayan rivers flow across the young fold mountains and are still in a youthful stage, while Peninsular rivers have been flowing in one of the world's oldest plateaus and have reached maturity. Hence, statement 2 is not correct.

• When Himalayan rivers enter the plains, there is a sudden reduction in the speed of water flow, which forms meanders and shifts their beds. In the case of Peninsular rivers, the hard rock surface and non-alluvial character of the plateau permits little scope for the formation of meanders. As such, the rivers of the Peninsular Plateau follow more or less straight courses. Hence, statement 3 is correct.

• Southern Oscillation is a coherent interannual fluctuation of atmospheric pressure over the tropical Indo-Pacific region. Hence option (c) is the correct answer.
• It is the atmospheric component of a single large-scale coupled interaction called the El Nino/Southern Oscillation (ENSO). The phase of the Southern Oscillation at a given point in time may be understood using the Southern Oscillation Index (SOI), which compares the difference in atmospheric pressure over Australia and Indonesia with that of the eastern South Pacific.

Volcanoes are classified on the basis of nature of eruption and the form developed at the surface. Major types of volcanoes are as follows:

• Shield Volcanoes

• Barring the basalt flows, the shield volcanoes are the largest of all the volcanoes on the Earth. The Hawaiian volcanoes are the most famous examples. These volcanoes are mostly made up of basalt, a very fluid type when erupted. For this reason, these volcanoes are not steep. They become explosive if somehow water gets into the vent; otherwise, they are characterised by low-explosivity. The upcoming lava moves in the form of a fountain and throws out the cone at the top of the vent and develops into cinder cone. Hence option (c) is the correct answer.

• Composite Volcanoes

• These volcanoes are characterised by eruptions of cooler and more viscous lavas than basalt. These volcanoes often result in explosive eruptions. Along with lava, large quantities of pyroclastic material and ashes find their way to the ground. This material accumulates in the vent openings' vicinity, leading to formation of layers, which makes the mounts appear as composite volcanoes.

• Caldera

• These are the most explosive of the Earth's volcanoes. They are usually so explosive that they tend to collapse on themselves rather than building any tall structure when they erupt. The collapsed depressions are called calderas. Their explosiveness indicates that the magma chamber supplying the lava is huge and in close vicinity.

• Flood Basalt Provinces

• These volcanoes outpour highly fluid lava that flows for long distances. Some parts of the world are covered by thousands of sq. km of thick basalt lava flows. There can be a series of flows with some flows attaining thickness of more than 50 m. Individual flows may extend for hundreds of km. The Deccan Traps from India, presently covering most of the Maharashtra plateau, are a much larger flood basalt province. It is believed that initially the trap formations covered a much larger area than the present.

• Mid-Ocean Ridge Volcanoes

• These volcanoes occur in the oceanic areas. There is a system of mid-ocean ridges more than 70,000 km long that stretches through all the ocean basins. The central portion of this ridge experiences frequent eruptions.

Types of Earthquakes:

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

• A special class of tectonic earthquake is sometimes recognised as a volcanic earthquake. 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.

o Tsunami is the effect of an earthquake, not a cause of it.

Dry hot deserts are good places for sand dune formation. Obstacles to initiate dune formation are equally important. There can be a great variety of dune forms.o Crescent-shaped dunes called barchans with the points or wings directed away from wind direction i.e., downwind, form where the wind direction is constant and moderate and where the original surface over which sand is moving is almost uniform. Hence, statement 1 is not correct, o Parabolic dunes form when sandy surfaces are partially covered with vegetation. That means parabolic dunes are reversed barchans with wind direction being the same, o Seif is similar to barchan with a small difference. Seif has only one wing or point. This happens when there is shift in wind conditions. The lone wings of seifs can grow very long and high. Hence, statement 2 is correct.

o Longitudinal dunes form when the supply of sand is poor and wind direction is constant. They appear as long ridges of considerable length but low in height. Hence, statement 3 is correct, o Transverse dunes are aligned perpendicular to the wind direction. These dunes form when the wind direction is constant and the source of sand is an elongated feature at right angles to the wind direction. They may be very long and low in height.

o When sand is plenty, quite often, the regular shaped dunes coalesce and lose their individual characteristics.

o Most of the dunes in the deserts shift and a few of them will get stabilised especially near human habitations.

A catchment is an area of land where water collects when it rains, often bounded by hills. As the water flows over the landscape it finds its way into streams and down into the soil, eventually feeding the river. Some of this water stays underground and continues to slowly feed the river in times of low rainfall.

o The sources of information about the interior of the Earth are divided into direct sources and indirect sources:

• Direct Sources

• The most easily available solid earth material is surface rock or the rocks we get from mining areas. Gold mines in South Africa are as deep as 3 - 4 km.

• Volcanic eruption forms another source of obtaining direct information. As and when the molten material (magma) is thrown onto the surface of the Earth, during volcanic eruption it becomes available for laboratory analysis.

• Indirect Sources

• Mining activity provides us with information about temperature and pressure which increases with the increasing distance from the surface towards the interior in deeper depths.

• Another source of information are the meteors that at times reach the Earth. However, it may be noted that the material that becomes available for analysis from meteors, is not from the interior of the Earth. The material and the structure observed in the meteors are similar to that of the Earth.

The other indirect sources include gravitation, magnetic field, and seismic activity (earthquakes). Seismic activity helps us in analysing the composition of the interior of the Earth based on the seismic waves.