Geomorphology Questions and Answers

Answer: B

Volcanic eruptions are most frequent in the Circumpacific belt.

The Circum-Pacific belt, the 'Ring of Fire', runs around the edges of the Pacific Ocean, along the Andes, the Rockies, Japan, the Philippines and New Zealand. Here oceanic plates are subducted beneath other plates, and it holds roughly two-thirds of the world's active volcanoes.

The Mid-Atlantic ridge has volcanic activity, as in Iceland, but far less. Mid-continental and intraplate volcanoes, such as hotspots like Hawaii, are much fewer.

Answer: B

The process that does not come under diastrophism is Heterogenic.

Diastrophism covers all processes that move, raise or build up parts of the Earth's crust. The NCERT geography text lists them as orogenic processes (mountain building through severe folding), epeirogenic processes (uplift or warping of large parts of the crust), earthquakes (local, relatively minor movements) and plate tectonics (horizontal movements of crustal plates).

Orogenic, earthquakes and plate tectonics are therefore all diastrophic. 'Heterogenic' is not one of these processes; the term that belongs in the list is epeirogenic.

Answer: D

Molten rock below the surface is called Magma.

Magma forms where rock melts in the crust or upper mantle. When it reaches the surface through a volcano it is called lava, so the difference between the two terms is simply where the molten rock is.

Basalt is a solid volcanic rock formed when lava cools quickly. A laccolith is a dome-shaped intrusive body formed when magma pushes up the overlying layers and solidifies underground.

Answer: B

Only statement 2 is incorrect, so the answer is Only 2.

The Sea of Galilee (Lake Tiberias) in the Jordan Rift Valley is described in standard geography textbooks as a lake formed when lava flows blocked the valley, so statement 1 is accepted.

Statement 2 is wrong because the Tafilalet oasis is in south-eastern Morocco, on the edge of the Sahara, not in Libya. Textbooks describe it as walled against dust storms, and the hot dust-laden desert wind is the simoom, but the country is misplaced, which makes the statement incorrect.

Answer: A

The correct code is A-3, B-2, C-4, D-1.

• Mount Merapi, one of the most active volcanoes in the world, is in Java, Indonesia.
• Taal, a volcano inside a lake, is in Luzon, the Philippines.
• Kilauea is a shield volcano on the island of Hawaii, United States of America.
• Mount Erebus, the southernmost active volcano, is on Ross Island, Antarctica.

Option (c) swaps Merapi and Taal, the two Southeast Asian volcanoes, and the others misplace Erebus or Kilauea.

Answer: B

The correct code is A-1, B-3, C-2, D-4.

• The Himalayas rose from the collision of two continental plates, the Indian and Eurasian.
• The Andes formed where the oceanic Nazca plate is subducted beneath the continental South American plate.
• The Black Forest in Germany is a block mountain, a horst raised between faults, beside the down-dropped Rhine rift valley.
• The Scottish Highlands are residual mountains, the worn-down remnants of a once much higher range.

Option (a) swaps the Black Forest and the Scottish Highlands, the two older European examples.

Answer: A

The landform is a barchan.

A barchan is a crescent-shaped sand dune that forms where wind blows steadily from one direction and sand is limited. Its horns point downwind and the whole dune migrates in the direction of the wind.

A zeugen is a tabular rock ridge left by wind erosion of alternate hard and soft layers. A playa is a shallow, often salty lake bed in a desert basin. A moraine is a ridge of debris deposited by a glacier.

Answer: B

Such deposits are called Loess.

Loess is homogeneous, typically unstratified, wind-blown silt, often yellowish and able to stand in near-vertical cliffs. Thick loess blankets of the middle latitudes, such as the Loess Plateau of China and the Mississippi valley deposits, were blown from glacial outwash plains and deserts.

Ergs are sand seas, large areas covered by dunes. Draas are very large compound dunes. Eolianite is wind-deposited sand, usually carbonate, that has been cemented into rock; none of these is unstratified silt.

Answer: D

Stream competence depends primarily on Flow velocity.

Competence is the size of the largest particle a stream can move. It rises very steeply with velocity: the maximum particle weight that can be moved is often stated to vary roughly with the sixth power of velocity, so a doubling of speed during a flood can move boulders that were immobile before.

The amount of suspended load relates to capacity (how much material is carried), not to the largest grain size. Water temperature and channel shape have only secondary effects, mainly through their influence on velocity and turbulence.

Answer: D

A hydrograph plots discharge against Time.

A stream hydrograph shows how the discharge (volume per unit time) at a gauging station rises after rainfall to a peak and then falls back along the recession limb. Reading it gives the lag time between peak rainfall and peak discharge and the shape of the flood wave.

Channel width, depth and velocity are components used to calculate discharge (discharge = width × depth × velocity), not the horizontal axis of a hydrograph.