NCERT Solutions for Class 11 Geography Chapter 2 - Structure and Physiography

76. Choose the right answer from the four alternatives given below.

(i) In which part of Himalayas do we find the Karewa formation?

(a) North-eastern Himalayas

(b) Himachal-Uttarakhand Himalayas

(c) Eastern Himalayas

(d) Kashmir Himalayas

Ans. (d) Kashmir Himalayas

(ii) In which of the following states is Loktak lake situated?

(a) Kerala

(b) Uttarakhand

(c) Manipur

(d) Rajasthan

Ans. (c) Manipur

(iii) Which one of the water bodies separates the Andaman from the Nicobar?

(a) 11° Channel

(b) Gulf of Mannar

(c) 10° Channel

(d) Andaman Sea

Ans. (c) 10° Channel

(iv) On which of the following hill range is the ‘Dodabeta’ peak situated?

(a) Nilgiri hills

(b) Anaimalai hills

(c) Cardamom hills

(d) Nallamala hills

Ans. (a) Nilgiri hills

77. Answer the following questions in about 30 words.

(i) If a person is to travel to Lakshadweep, from which coastal plain does he prefer and why?

Ans. In the Arabian Sea, there are group of islands known as Lakshadweep. These islands are situated between 280 and 480 kilometres off the coast of Kerala. It is closest to the Malabar Coast. As a result, we will arrive at the Lakshadweep islands from the Malabar Coast in the shortest period of time.

(ii) Where in India will you find a cold desert? Name some important ranges of this region.

Ans. The Kashmir Himalayas’ north-eastern region is a cold desert between the Greater Himalayas and the Karakoram mountains. Principal ranges of this region are Ladakh, the Karakoram, the Jasker, and the Pir Panjal.

(iii) Why the western coastal plain is devoid of any delta?

Ans. Rivers on the western shore have a fairly high incline. As a result, these rivers have a single, continuous flow. Therefore, they do not create a delta. Therefore, we are unable to locate any delta along the western shore.

78. Answer the following questions in not more than 125 words.

(i) Make a comparison of the island groups of the Arabian Sea and the Bay of Bengal.

Ans. Lakshadweep islands are located in the Arabian Sea, and Andaman and Nicobar islands are located in the Bay of Bengal.

(a) There are roughly 572 islands in the Bay of Bengal island groups. These are located between 92°E and 94°E and between 6°N and 14°N. T he two main island groups are are Labyrinth and Richie’s archipelago. The Andaman (north) and Nicobar islands comprise the entire group of islands (south). They are separated by the 10° Channel, a huge body of water. Some smaller islands were formed by volcanic activity. The Nicobar Islands contains a lonely island and India’s only active volcano the Barren Island.

(b) In the Arabian Sea there are the Lakshadweep Islands. They are dispersed between latitudes 71°E and 74°E and between 8°N and 12°N. These are situated between 280 and 480 kilometres inland from Kerala’s coast. The entire island chain is made of deposits of coral. There are around 36 of them, and 11 of them are inhabited. The largest island is Minicoy.

(ii) What are the important geomorphological features found in the river valley plains?

Ans. Alluvial fans are created when streams from higher elevations come down foot slope plains with a low gradient. Streams running across steep slopes typically carry relatively coarse loads. This burden eventually becomes too heavy for the streams to carry across milder gradients, so it is discharged and dispersed as an alluvial fan, a wide low to high cone-shaped deposit. Typically, streams that flow across fans are not kept in their original channels for very long. Instead, they move positions across the fan, creating a number of distributaries. In humid environments, alluvial fans generate low cones that are typically low with a gradual slope. Delta is similar to alluvial fans but forms in a different area. The rivers’ mass is stretched out and emptied into the ocean. This weight spreads and builds if it is not dispersed along the shore or taken far out to sea. These locations above flood plains include gritty sediments that were built up by abandoned or cut-off channels. Silt and clay are considerably finer materials carried  by the flood deposits of water spills. The term “delta plains” refers to the flood plains in a delta. A significant river depositing landform is the floodplain. Large-sized sediments are deposited first when the stream channel transitions into a moderate slope. As a result, fine-grained materials like sand, silt, and clay are typically carried by relatively slow-moving streams in gentler channels that are most often found on  the plains, where they are then dumped over the bed and during floods above the bed. The lush alluvial soil in these river valley plains supports a wide range of crops, including wheat, rice, sugarcane and jute, and as a result, it sustains a sizable population.

(iii) If you move from Badrinath to Sunderbans delta along the course of the river Ganga, what major geomorphological features will you
come across?

Ans. Along the Ganges River’s path from Badrinath to the Sunderbans Delta, we would come across the following significant geomorphological features:

(a) V-shaped Valleys: Valleys develop as small, narrow rills that gradually grow into long, wide gullies. The gullies then continue to deepen, expand, and extend to form V-shaped valleys.

(b) Gorge: A gorge is a deep valley with abruptly straight or extremely steep sides.

(c) Canyon: A canyon can be as deep as a gorge and is characterised by steep, step-like side slopes. A gorge is almost equal in width at its top as well as at its bottom.

(d) Waterfall: This natural phenomenon occurs when rivers in hilly areas begin to fall into holes.

(e) Plunge pools: After a tiny, shallow depression appears, stones and boulders gather there and are spun by the water, which causes the depressions to enlarge.
Such depressions gradually merge together in a sequence, deepening the stream valley. Large potholes that are fairly deep and wide also occur at the base of waterfalls as a result of the force of the water and the rotation of the stones.

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