3.6 Weathering And Mass Movement At The Coast

Question 1

Sub-aerial processes

Answer 1

Weathering and mass movement.

Question 2

Weathering

Answer 2

Gradual breakdown of rock. Divided into 3 categories: biological, chemical and mechanical. Can also increase rate of erosion

Question 3

Mass movement

Answer 3

Movement of weathered material down slop as a result of gravity

Question 4

Freeze-thaw weathering

Answer 4

Mechanical. Rain > water in crack freeze > ice expands > widens crack > cycle continues

Question 5

Scree

Answer 5

Collection of loose rock found on sides of hills and mountains

Question 6

Salt-weathering

Answer 6

Mechanical. Salt water evaporates > leaves salt crystals > grows time causing cracks > can also corrode rock

Question 7

Wetting and drying

Answer 7

Mechanical. Rocks rich in clay expand when wet and contract when dry. Causes cracks and breaking

Question 8

Biological weathering occurrences

Answer 8

Plant roots in rock widening. Water running through vegetation becomes acidic. Animals burrowing into rock. Marine organisms secreting acid (limpets)

Question 9

Carbonation

Answer 9

Chemical weathering. Process of rock minerals reacting with carbonic acid. Dissolves minerals.

Question 10

Mass movement factors

Answer 10

Slope of cliff.
Rock type and structure.
Vegetation cover.
Antecedent conditions.

Question 11

Soil creep

Answer 11

Mass movement. Slowest form. Downhill movement of individual particles.

Question 12

Solifluction

Answer 12

Mass movement. Occurs mainly in tundra areas, where ground is frozen. Top layer thaws, surface layer becomes saturated and flows over frozen subsoil.

Question 13

Earth flows and mudflows

Answer 13

Increase in water amount reduces friction. Earth and mud flows over underlying bedrock

Question 14

Rock falls

Answer 14

Occurs on slopes over 40⁰. Material, when broken, falls vertically.

Question 15

Rock/debris slides

Answer 15

Slabs of rock sliding over a slide or slip plane. Increase in water reduces friction

Question 16

Slumps

Answer 16

Often occurs in saturated conditions. Rotational movement in slumps. Moderate or steep. Causes rotational scars.