Rock types and rates of erosion

Question 1

Hardness

Answer 1

Igneous rocks formed through heating and compression are more resistant to erosion and form many high cliffs in the Northwest of Britain

Soft rocks such as unconsolidated sands and clays are effected more by erosional processes and of lead to the formation of mud slides and slumps

Question 2

Chemical Composition

Answer 2

Some rocks such as quartzite and most sandstones are made almost completely of silica which makes them less susceptible to chemical erosion processes and builds up the resistance of rock

Iron compounds oxidise in some sandstones and feldspars are altered into clay by hydrolysis which makes the rocks vulnerable to sub aerial processes and marine processes

Question 3

Permeability

Answer 3

An open textured limestone and cracks or joints in chalk or lime stone allow surface waters to seep through the cracks and make the rocks less susceptible to sub aerial processes and explains why chalk cliffs are almost vertical like the white cliffs of Dover in Kent