Types of mass movement

Question 1

Soil Creep:

Answer 1

Common in humid climes with the movement of less than 1cm per year

Soil expands when it freezes, gets wet or is heated up in the sun

As the soil expands, it lifts at right angles to the slope

When the soil shrinks, it falls straight back down

Soil creep takes a long time because the soil moves only a millimetre to a few centimetres at a time

Question 2

Flow

Answer 2

Occurs on slopes between 5° and 15° with speeds between 1 to 15km per year

Usually happens after the soil has become saturated with a flow of water across the surface

Vegetation is flattened and carried away with the soil

Question 3

Slide

Answer 3

A movement of material ‘en-masse’ which remains together until hitting the bottom of a slope

Question 4

Fall

Answer 4

Slopes are steep and movement is rapid

Caused by a number of reasons:

Extreme weathering: Freeze-thaw action can loosen rocks that become unstable and collapse

Rainfall: Too much rain will soften the surface leading to the collapse of the slope

Earthquakes can dislodge unstable rocks

Hot weather can dry out soil causing it to shrink and allowing rocks to fall