Comp 2 EQ2 Flashcards
What is the difference between a concordant and a disconcordant coastline?
A concordant coastline is when the rock type is parallel to the sea and the rock is constant across it. A disconcordant coast is when the rock layers are perpendicular to the beach.
What are some features of a disconcordant coast?
Headlands and bays are common to disconcordant beaches as the softer layers of rock are eroded much faster for in the bays in between the more resistant rock forming the headlands.
What are some features of concordant coastlines?
Coves are often common as water gets through cracks and erode the less resistant rock behind much faster. If sand covers a cove by long shore drift it becomes a lagoon.
How are headlands eroded?
Joints in the rock (vertical cracks) are opened up by hydraulic action, they are then eroded into caves which eventually break through the headland forming an arch. The arch eventually splits creating a stack separated from the cliff which erodes into a stump.
What makes waves more powerful?
Wind speed and the fetch (the distance of uninterrupted contact between the sea and the wind) and how long the wind has been blowing are all factors that effect power of the waves.
Define a constructive wave
A small wave usually in the warmer months when there is less strong wind. It brings sediment up the beach with its swash but has a weak backwash so the sediment is deposited.
Destructive waves.
Waves in the winter are much stronger, because of the wind, and pull sediment away with a strong backwash.
What are the three types of cliff erosion?
Hydraulic action, abrasion and attrition.
What is hydraulic action?
Water is forced into cracks which compresses air so when the water leaves the air explodes outwards, widening the cracks.
What is abrasion?
Abrasion is when lose sediment is thrown against the cliff and chisels away at the rocks.
What is attrition?
When sediment is thrown together in the waves and grinds together making all the sediment smaller and rounder.
What is long shore drift?
Long shore drift is when sediment is moved by waves hitting the beach diagonally, the swash moves it up the beach and the backwash pulls it back down along the beach until it is deposited often in the mouth of a river or across a cove.
What features can longshore drift create?
Long shore drift can create a lagoon by cutting of the entrance and creating a bar in between the cove and the beach as well as a split in a river mouth. This is created when the sand pushed up the river by the sea at high tide and down by the river at low tide causing a curve that holds water still. In both places salt marshes can form.
