Geomorphology Questions and Answers

Answer: B

Both statements are false, so the answer is Both (i) and (ii) are false.

The statements describe the processes correctly but attach the wrong names. A beach that receives sand faster than it loses it widens and builds seaward; that is progradation, not retrogradation as statement i says. A beach that loses sand faster than it gains it narrows as the shoreline moves landward; that is retrogradation, not progradation as statement ii says.

Because the two terms have been swapped, neither statement is true, which rules out the other options.

Answer: D

By area the terrestrial environment is dominated by landforms made by fluvial action.

Running water acts on almost every land surface that receives rain, carving valleys and building floodplains, deltas and fans, so river-made landforms cover the greatest share of the continents. Even deserts carry many fluvial features such as wadis and alluvial fans.

Wave and current landforms are limited to coasts, wind landforms to arid regions, and glacial landforms today to high latitudes and high mountains (though once more extensive), so each covers less area than fluvial landforms.

Answer: A

The evidence of seafloor spreading is Palaeomagnetism (Magnetic Anomalies).

Rocks on the ocean floor record the direction of the earth's magnetic field when they cooled. In the early 1960s Vine, Matthews and Morley showed that these records form stripes of normal and reversed polarity lying symmetrically on either side of the mid-ocean ridges, exactly as Hess's hypothesis predicted if new crust forms at the ridge and moves outward.

Upwelling of magma at the ridges is the mechanism of spreading, and continental drift and plate movement are the theories it supports, not the evidence for it.

Answer: B

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

• Horizontal forces act tangentially, compressing or stretching the crust into folds and faults.
• Epeirogenetic forces cause slow vertical uplift or subsidence of large areas.
• Catastrophic forces, such as earthquakes and volcanic eruptions, are sudden.
• Exogenetic forces (weathering, erosion) are destructional, wearing down relief.

Option A gives catastrophic forces vertical movement, C pairs horizontal forces with vertical movement, and D makes horizontal forces destructional.

Answer: C

The order of mineral stability is given by (1) and (3), the Goldich dissolution series and Bowen's reaction series.

Bowen's reaction series gives the order in which silicate minerals crystallise from a cooling magma, from olivine at high temperature to quartz at low temperature. Goldich (1938) showed that minerals weather in the same order: those formed at the highest temperatures, such as olivine, are least stable at the surface, while quartz is the most resistant.

Penck and Holmes are not the authors of any such series, so every option including (2) or (4) is wrong.

Answer: C

(A) is true but (R) is false.

Rejuvenation is the renewal of a river's erosive power when its base level falls or the land is uplifted. The river cuts down again, producing knickpoints, river terraces and incised meanders, so the assertion is true.

The reason is false: rejuvenation does not shorten the cycle of erosion. It interrupts it and starts a new cycle, so the old landscape is never carried through to a peneplain and the time needed to reach that end stage is lengthened. Since (R) is false, options A, B and D fail.

Answer: A

A sag pond is related to an active strike slip fault.

Where two blocks slide past each other along a strike-slip fault, bends and steps in the fault leave small sections of ground pulled apart and sunk. Water collects in these depressions, forming sag ponds, which are a classic sign of an active fault, as along the San Andreas Fault in California.

A meandering river leaves oxbow lakes, coastal processes form lagoons, and wind deflation hollows out basins; none of these is called a sag pond.

Answer: A

From lower to higher, the order is (4), (2), (3), (1).

The standard hillslope profile (Wood 1942, adopted by L.C. King) has four elements from the crest down: the convex waxing slope at the top, the steep rock free face, the constant slope of debris below it, and the concave waning slope at the foot. Reading upward from the base gives waning, constant, free face, waxing.

The other codes misplace the free face above the waxing slope, start from the constant slope, or put the free face below the constant slope.

Answer: C

A nappe is formed by Only (1) and (2), thrust faulting and recumbent folding.

A nappe is a large sheet of rock carried many kilometres over younger rocks. It develops when compression folds strata into a recumbent fold lying on its side, and the fold then breaks along a low-angle thrust fault so that the upper limb is pushed forward. The Alps are the classic example.

Jointing is cracking of rock without movement, so it plays no part. Options naming only one of the two processes leave out half of the mechanism.

Answer: C

Kame terraces are assigned to glacio-fluvial processes.

A kame terrace forms along a valley side where meltwater streams flow between the edge of a melting valley glacier and the valley wall. The streams deposit sorted, stratified sand and gravel in this trough; when the ice melts away, the deposit is left as a flat-topped terrace on the hillside. Deposition by meltwater is glacio-fluvial.

Glacio-lacustrine deposits are fine, varved silts and clays laid down in ice-dammed lakes. Aeolian processes are wind-driven, such as loess. Glacio-eustatic refers to world-wide sea-level change caused by the growth and melting of ice sheets, not a landform-building process.