Lithology Flashcards
Lithology
Refers to physical properties of a rock, such as its resistance to erosion.
How does Lithology of the coast affect how quickly it is eroded?
Hard rocks e.g. Granite, are resistant to weathering and erosion so a coastline made of this type of rock will change more slowly. For example, Lands End.
Soft rocks e.g. Limestone, are more susceptible to weathering and erosion so these coastlines will change more quickly. For example, Dorset.
Description of a Concordant Coast
Alternating layers of soft and hard rock that run parallel to the coastline. Hard rock acts as a protective barrier to softer rock behind it, preventing erosion. Therefore Concordant coasts are eroded more slowly.
Landforms on a Concordant Coast
Few landforms due to constant layer of hard rock being difficult to erode. If hard rock is breached, softer rock is exposed and a cove forms, e.g. Lulworth Cove.
Description of a Discordant Coastline
Alternating layers of hard and soft rock are perpendicular to the coast.
Landforms on a Discordant Coastline
Soft rock and hard rock are both exposed. Soft rock is eroded faster than hard. Differential erosion occurs between different rock types, creating headlands and bays.
What are bedding layers?
When rocks are formed from layers of different rocks, it is known as beds.
How do bedding layers become more susceptible to erosion?
Beds are subject to tectonic forces that tilt and deform them so dip at an angle. The angle of the dip affects erosion and profile of resulting cliffs.
Horizontal beds
Produce steep cliffs with notches where differential erosion takes place.
Steep profile with softer rock beds will be eroded to notches.
Seaward Dip
Produce gentler cliffs that are less stable as material slides down in mass movements.
Landward dip
Produce stabler and steeper cliffs.
