Geomorphology Questions and Answers

Answer: D

The basic goal was to provide systematic description of landforms and genetic classification of landforms.

W.M. Davis described every landscape as a function of structure, process and stage, and traced landforms through a sequence of youth, maturity and old age ending in a peneplain. The model was meant as a framework for describing landforms systematically and classifying them by their origin and stage of development.

Erosional landforms were the material of the model, not its aim. Davis assumed rapid uplift followed by stillstand, so the causes of crustal movement and the history of climatic change lay outside what the cycle set out to explain.

Answer: A

From lowest to highest the order is (4) (3) (2) (1): abyssal plain, guyot, ridges and runnels, sea-cliff.

The abyssal plain is the flat deep-ocean floor, generally 3,000 to 6,000 m below sea level. A guyot is a flat-topped seamount that rises from the ocean floor but whose top is still submerged, often hundreds of metres down. Ridges and runnels are low sand ridges and troughs on the intertidal beach, around sea level. A sea-cliff rises above the shore at the landward edge.

Options starting with the guyot or with the sea-cliff put a feature higher or lower than it actually lies.

Answer: A

The correct matching is a-(1), b-(3), c-(2), d-(4).

In Anthony Young's terminology for slope profiles, a segment is a part of the slope on which the angle stays roughly constant (a straight stretch), while an element is a part on which the curvature stays roughly constant.

A convex element is one on which the angle increases downslope, as on the rounded upper part of a hillside. A concave element is one on which the angle decreases downslope, as at the foot of a slope. The other codes swap segment with element or convex with concave.

Answer: A

The correct relation is L < S < P.

Primary (P) waves are compressional and travel fastest, about 6 km/s in the crust, so they arrive first. Secondary (S) waves are shear waves, about 3.5 km/s in the crust, and arrive second. Surface (L, Love) waves travel along the surface and are the slowest, though they do the most damage.

The other relations either put the S or L waves above P, or rank L above S, which contradicts the order in which seismographs record them.

Answer: D

The term not applicable to weathering is slump.

A slump is a form of mass movement: a block of earth or rock slides down along a curved, spoon-shaped surface and rotates backwards as it moves. It is a transport process acting on material that weathering has already prepared.

The other three belong to weathering. Regolith is the layer of loose weathered material over bedrock, saprolite is rock chemically weathered in place that keeps its original structure, and chelation is a chemical weathering process in which organic compounds bind and remove metal ions from minerals.

Answer: A

The most common volcanic cone is the composite cone.

Composite cones, or stratovolcanoes, are built of alternating layers of lava and pyroclastic material such as ash and cinders. They form the steep, symmetrical peaks of subduction zones around the Pacific Ring of Fire, such as Fuji, Mayon and Vesuvius, and are the typical volcano of popular imagination.

A caldera is a large depression formed when a volcano collapses after an eruption, not a cone. Ash or cinder cones are small, short-lived cones, and lava domes are bulging masses of viscous lava. All are less common than composite cones.

Answer: A

Both (A) and (R) are correct and (R) is the correct explanation of (A).

Large avalanches most often start on slopes of roughly 30° to 50°. On gentler slopes the snow does not slide readily, and on steeper slopes it cannot build up, because it sloughs off in small amounts as it falls.

That is what (R) states: the 30° to 50° range is where enough snow can accumulate and still become unstable. Because snow accumulation on such slopes is the condition for a large avalanche, (R) explains (A).

Answer: A

The answer is the diapir.

A diapir is an anticlinal fold or dome in which a mobile core, such as salt, gypsum or magma, rises and pierces or arches the overlying rock layers. The intruding material pushes upward because it is lighter or more plastic than the rocks above.

A salt plug is one kind of diapir in which salt has pierced right through, but the general term for the fold is diapir. A salt glacier is salt flowing out over the surface, and dip is the angle of inclination of a rock layer, not a fold.

Answer: C

Both statements are correct.

Slopes are classed by which process limits their development. On weathering-limited (weathering-controlled) slopes, transport could remove material faster than weathering produces it, so the actual rate of regolith production is less than the potential rate of removal, and bare rock is common (I).

On transport-limited slopes, weathering produces regolith faster than the transport processes can remove it, so a thick soil cover builds up (II). The two statements are the standard definitions, so options rejecting either are wrong.

Answer: B

The incorrect statement is Primary waves are highly destructive.

Primary (P) waves are the fastest seismic waves and arrive first, but they are compressional waves of small amplitude and do relatively little damage. The most destructive are the surface waves, which arrive last and shake the ground with large, long-period motion.

The other statements are correct: P waves travel through solids, liquids and gases; secondary (S) waves are transverse and cannot pass through liquids, which is how the liquid outer core was discovered; and surface waves are long waves.