10.2 Weathering and mass movement Flashcards
What causes cliffs to collapse?
➢ Due to different types of weathering
What are the three types of weathering?
➢ Mechanical weathering
➢ Chemical weathering
➢ Biological weathering
What is mechanical weathering?
➢ The disintegration of rocks
➢ Piles of rocks fragments called scree can be found at the foot of cliffs
What is chemical weathering?
➢ Caused by chemical changes
➢ Rainwater which is slightly acidic - dissolves certain types of rocks
What is biological weathering?
➢ Due to the actions of flora and fauna
➢ Plant roots grow in cracks into the rocks
What are the 3 process of weathering?
➢ Freeze-thaw - mechanical
➢ Salt weathering - mechanical
➢ Carbonation - chemical
What is the process of freeze-thaw weathering?
➢ Water collects in cracks in the rock
➢ Water freezes to form ice at night
➢ When the temperature rises and ice thaws - water will seep deeper into the rock
➢ The expansion of the ice causes stresses and cracks are enlarged
➢ Rock fragments eventually break off due to repeated freeze-thawing
What is the process of salt weathering?
➢ Seawater contains salt. When the water evaporates it leaves behind salt crystals
➢ In cracks and holes, these salt crystals grow and expand
➢ This puts pressure on the rocks and flakes may eventually break off
What is the process of carbonation?
➢ Rainwater absorbs CO2 from the air and becomes slightly acidic
➢ Contact with alkaline rocks - such as chalk and limestone produces a chemical reaction causing the rocks to slowly dissolve
What is a rockfall?
➢ Fragments of rock break away from the cliff face, often due to freeze thaw weathering
What is a landslide?
➢ Blocks of rock slide downhill
What is a mudflow?
➢ Saturated soil and weak rock flow down a slope
What is mass movement?
➢ The downward movement or sliding of material under the influence of gravity
What are the 4 process of mass movement?
➢ Rockfall
➢ Mudflow
➢ landslide
➢ Rotational slip/slump
What is a rotational slip/slump?
➢ Slump of saturated soil and weak rocks along a curved surface
