Mass Movement and Weathering

Question 1

Slump rotational Slide

Answer 1

A slump is a form of mass wasting that occurs when a coherent mass of loosely consolidated materials or rock layers moves a short distance down a slope. … Rotational slumps occur when a slump block, composed of sediment or rock, slides along a concave-upward slip surface with rotation about an axis parallel to the slope.

Question 2

Salt Crystallisation

Answer 2

This is when salt crystals are deposited in cracks and over time the salt accumulates and applies pressure to the crack (similar to freeze-thaw weathering)

Question 3

Soil Creep

Answer 3

Soil creep is a slow but continuous process. It typically occurs on most slopes over 5 degrees. Soil creep rarely exceeds speeds of 1cm per year. Creep occurs as the result of repeated expansion and contraction of material. Cycles of freeze thaw heave particles up on freezing and allow them to fall further down slope when the ice melts. Alternating hydration and dehydration have the same effect.

Question 4

Earth Flow

Answer 4

Earth flows tend to be faster than slow creep but less sporadic. Earthflows have a characteristic “hourglass” shape. The slope material liquefies and runs out, forming a bowl or depression at the head.

Question 5

Land Slides

Answer 5

This is the downslope movement of a large block of material that moves as a coherent mass. This means it retains its internal structure until hitting the base of the slope and fracturing into smaller pieces. It is more common over wet periods, on steep slopes and often occurs on coastlines.

Question 6

Mudflows

Answer 6

A mudflow is an earthflow consisting of material that is wet enough to flow rapidly and that contains at least 50 percent sand, silt, and clay-sized particles.

Question 7

Rock Fall

Answer 7

Rockfalls are usually associated with near vertical slopes. Only more resistant rock can sustain these angles on the coast. They are most commonly triggered by undercutting in the inter-tidal zone or freeze-thaw weathering.

Question 8

Run-off

Answer 8

Run-off has the ability to move fine material downslope, particularly where overland flow occurs as a thin, continuous layer (sheet flow) and washes silt and clay sized particles.

Question 9

Sub-aerial Processes

Answer 9

Sub-aerial processes are land based processes which alter the shape of a coastline. They’re a combination of both weathering and mass movement.

Question 10

Weathering

Answer 10

Weathering is the breaking down or dissolving of rocks and minerals on Earths surface