Geomorphology Questions and Answers

Answer: D

The hills of debris are called moraine.

A glacier carries a load of unsorted rock debris. Where the ice front stays in one place for a while as it retreats, that debris piles up as a ridge or hill across the valley, a terminal or recessional moraine; debris along the sides forms lateral moraines.

Glacial till is the unsorted material itself, not the landform it builds. Outwash deposits are sorted sands and gravels laid down by meltwater streams beyond the ice, usually as plains. Drumlins are smooth, elongated mounds shaped under moving ice, not dumped as the glacier retreats.

Answer: B

The one that is not an island arc is the Hawaiian chain.

Island arcs form where one oceanic plate subducts beneath another: magma rising from the subducting plate builds a curved line of volcanic islands beside a deep trench. The Aleutian, Philippine and Japanese islands are all of this kind, around the Pacific Ring of Fire.

The Hawaiian Islands lie in the middle of the Pacific plate, far from any plate boundary. They formed as the plate moved over a stationary hotspot, producing a straight chain of volcanoes that grow older to the northwest, not an arc above a subduction zone.

Answer: B

The key gives L. C. King as the critic who said that the senile man talked about the senile landscape of W. M. Davis.

Davis described a landscape as passing through youth, maturity and old age, ending in a low, nearly flat peneplain, which he called the stage of 'senility'. Lester C. King, the South African geomorphologist, was one of the sharpest opponents of this scheme: he argued that scarps retreat in parallel and that landscapes evolve by pediplanation, not by down-wearing to a peneplain. That fits a sarcastic remark about 'senile landscapes'.

Walther Penck also opposed Davis, but his objection was that uplift and denudation go on together. R. J. Chorley wrote a critical history of Davis's ideas, and Wooldridge worked in the English Davisian tradition, so neither suits as well. I could not trace the exact remark to a named source, so the attribution to King rests on the official key and on King's known stance; treat it as the keyed reading, not a quotation confirmed from the original.

Answer: B

The one influenced by Darwin was W. M. Davis.

Davis's cycle of erosion (1899) carries Darwin's evolutionary thinking into landforms: a landscape is born by uplift and then passes through orderly stages of youth, maturity and old age, each landform 'evolving' from the one before. Davis himself acknowledged the influence of Darwin's ideas of gradual change through time.

Walther Penck (spelt Penk here) and L. C. King developed models of slope development based on the relation between uplift and erosion, largely as alternatives to Davis, and James Dana was a geologist known for mountain-building and coral reef studies.

Answer: D

The feature is a barrier spit.

A spit is a ridge of sand or shingle deposited by longshore drift that is attached to the mainland at one end and extends into open water at the other, often curving landward at its tip (recurves). When it partly closes the mouth of a bay or lagoon, with the lagoon or marsh behind it, it is called a barrier spit.

A chenier ridge is a beach ridge resting on marsh or mudflat deposits and is not attached at one end. A beach berm is the nearly flat terrace on the backshore, and a fringing reef is a coral reef growing next to the shore, not a depositional barrier.

Answer: C

The correct sequence is cliff - notch - cave - arch - stack.

Waves attacking a headland first undercut the base of the cliff, forming a wave-cut notch. Continued erosion along joints and weaknesses enlarges the notch into a cave. Caves cut from both sides of a headland meet to form an arch. When the roof of the arch collapses, the seaward part is left standing as an isolated stack, which may later be worn down to a stump.

The other orders put the stack before the arch or the cave before the notch, which reverses how the erosion proceeds, and the last option runs the whole sequence backwards.

Answer: C

A narrow gap through which water flows across a ridge is a water gap.

A water gap is cut by a river that maintains its course across a rising ridge (antecedent drainage) or that was superimposed from overlying rocks, so the river still flows through the notch it carved.

A wind gap is the same kind of notch from which the river has since been diverted, usually by river capture, so no water flows through it now. A dry valley is a valley without a permanent stream, and a col is a low pass or saddle between two peaks, not a gap carrying a river.

Answer: B

The pair that does not include weathering products is ventifacts-erratics (printed 'Vertifacts').

Ventifacts are stones faceted and polished by wind-blown sand, a product of wind abrasion, an erosional process. Erratics are boulders carried by glaciers and left far from their source, a product of glacial transport. Neither is produced by weathering in place.

The other pairs are weathering products: tafoni and alveoli are cavernous hollows produced by salt and granular weathering, saprolite is rock chemically rotted in place, and laterite is the iron- and aluminium-rich residue of intense tropical weathering.

Answer: C

Loess and stone pavements both result mainly from deflation.

Deflation is the removal of loose fine particles by the wind. The silt and dust it lifts are carried away and deposited elsewhere as loess, while the coarse pebbles left behind become concentrated at the surface as a stone (desert) pavement that protects the ground beneath.

Abrasion is the wearing of rock by wind-blown sand and produces ventifacts and yardangs. Cavitation (printed 'Caritation') is erosion by collapsing bubbles in fast-flowing water, and cavernous weathering produces tafoni. None of these explains a dust deposit and a lag of stones.

Answer: B

The streamlined wind-aligned ridges are yardangs.

Yardangs are elongated ridges carved by wind abrasion and deflation in soft, cohesive rock or sediment. They are aligned parallel to the prevailing wind, with a blunt upwind end and a tapering downwind end, so they look like an upturned boat hull.

Deflation hollows are depressions, not ridges. Drumlins and roches moutonnees are glacial landforms shaped by moving ice: a drumlin is a streamlined hill of till, and a roche moutonnee is a bedrock knob smoothed on the up-ice side and plucked on the down-ice side.