Geological Structure And Cliff Profiles Flashcards
What are cliff profiles influenced by
Influenced by geology, especially the resistance to erosion of the rock, and the dip of rock strata in relation to the coastline
What are joints
Fractures in rocks created without displacement
When do joints form in igneous rock
As magma contracts as it looses heat
When do joints form in sedimentary rock
When rock is subject to compression or stretching by tectonic forces or weight of overlying rock
How can jointing increase erosion
Jointing increases erosion rates by creating fissures which erosional processes such as hydraulic action can exploit
What are faults
Major fractures in rocks created without created by tectonic forces, with displacement of rocks either side of the fault line
How do faults increase rate of erosion
Due to zones of faulted rock being much more easily eroded
What are folds and how are they formed
Folds are bends in rocks and formed by sedimentary rock layers being squeezed by tectonic forces or weight
How do folds lead to rock becoming more easily eroded
Due to folds often being heavily fissured and jointed and increasing angle of dip
What is the dip
Dip is the angle of inclination of the rock strata from the horizontal
What are micro features
Small scale features such as caves or wave cut notches which form part of a cliff profile
Where do micro features form
In areas weakened by heavy jointing, which have faster erosion rates therefore enlarging the joints to form a sea cave
What are the ways lithology affects resistance
Mineral composition, rock class, structure, dip of strata
How does mineral composition affect resistance
Some rocks contain reactive minerals easily broken down by chemical weathering. Other minerals are more inert that chemically weather more slowly, if at all
