Geomorphology Questions and Answers

Answer: C

The lateral planation theory of pediment formation was proposed by Gilbert. G.K. Gilbert argued in the 1870s from his work in the Henry Mountains that streams issuing from a mountain front swing from side to side and bevel the rock into a gently sloping surface, the pediment.

Davis is associated with the cycle of erosion and the peneplain, not with a pediment theory. Lawson is linked to the sheetflood and rain-wash ideas of pediment formation in arid regions, and McGee to the sheetflood concept for desert slopes. Lateral stream swinging is Gilbert's contribution to the question.

Answer: A

The correct matching is a-iii, b-iv, c-ii and d-i. Geomorphology is the textbook by Lobeck (Geomorphology: An Introduction to the Study of Landscapes), Essays in Geomorphology is by Dury, Physical Geography is by Strahler, and An Outline of Geomorphology is by Wooldridge and Morgan.

Every other option pairs at least one of these books with a wrong author, for example giving Strahler the Geomorphology title or Dury the outline of Geomorphology, so only the first set of codes matches all four correctly.

Answer: A

According to the official key, the feature that is strongly presumptive of a fault-line scarp is superimposed drainage across a fault. A fault-line scarp is formed by erosion along a fault and is not the scarp of the original fault movement, so the evidence offered is about the drainage and rock structure, not the movement itself.

Frequent severe earthquakes only show tectonic activity in a region. A poor correlation between rock resistance and topographic forms points to a structural cause but does not single out a fault-line scarp. Actual identification of a fault plane along a scarp would show a true fault scarp, not a scarp that has been formed by erosion after the faulting. This item rests on the key and a reviewer may wish to check it.

Answer: D

Paternoster lakes are features typical of glacial troughs. They are a chain of small lakes strung along the floor of a glaciated valley, like beads on a rosary, and fill hollows scooped out by the ice or dammed by moraines and rock steps.

Lava plains, piedmonts and deserts have no such chain of lakes along a trough. Piedmont and desert surfaces are shaped by running water and wind, and lava plains by volcanic outpouring, so only the glacial trough fits.

Answer: A

The correct matching is a-i, b-iv, c-ii and d-iii: the two-cycle theory of cavern formation is by Davis, the water table theory by Swinnerton, the static water zone theory by Garner, and the invasion theory by Malott.

The other options give at least one theory to the wrong scholar, for example crediting Swinnerton with the static zone theory or Malott with the water table theory, so only the first set of codes is entirely right.

Caves in limestone form where groundwater dissolves the rock along joints and bedding planes, and the scholars named here differ over whether this happens above, at or below the water table.

Answer: A

Plucking (quarrying) is the process typical of glacial erosion: ice freezes onto jointed rock, and as the glacier moves it tears blocks away, which is why glacial valleys have rock steps and rough floors.

Hydraulic action is the force of moving water on rock and is a river or marine process. Deflation is the removal of loose material by wind, and corrosion is the chemical or abrasive wearing of rock by water, so none of them is typical of glaciers.

Answer: A

Both statements are true and the Reason explains the Assertion. Chemical weathering depends on water and heat, so in the humid tropics, where rain is heavy and temperatures high all year, rocks decay chemically to great depths.

The second statement is not a separate fact but the cause of the first: an abundance of water and high temperatures speed up reactions such as hydrolysis and oxidation. Hence the options saying the reason is not the explanation, or that one statement is false, are wrong.

Answer: B

Crickmay, disagreeing with Davis, used the term panplane in place of peneplain. His idea was that lateral stream planation widens valleys and produces a plane surface by the sideways cutting of streams, instead of the general down-wearing of the whole land assumed by Davis.

Pediplain is the term of L.C. King, and etchplain is linked to the deep weathering and stripping idea. A structural plain is a surface formed by a resistant bed and not a term for a worn-down surface.

Answer: C

Vasudhara Tal is a Glacial lake.

Vasudhara Tal lies in the upper Dhauliganga basin of Chamoli at a height of about 4,700 m, fed by the meltwater of the surrounding glaciers and dammed by glacial deposits. Such lakes are watched closely because a breach can cause a glacial lake outburst flood.

Landslide lakes form when debris blocks a river, volcanic lakes fill craters, and solution lakes form where water dissolves limestone; none applies here.

Answer: B

Both statements are correct, so the answer is Both (1) and (2).

The Shiwaliks (outer Himalaya) are separated from the Lesser (Middle) Himalaya to their north by the Main Boundary Thrust, a major fault along which the older rocks of the Lesser Himalaya are pushed over the Shiwalik sediments.

The Shiwaliks are also the youngest range of the Himalaya, built from the debris carried down by rivers from the rising mountains and uplifted only in the late Tertiary.