Coastal and River landforms Flashcards
What is a beach
A depostional landform made by sand or pebbles
What do waves transport
Material up and down the beach and if they approach at an angle spits can form
What is a headland and bay
Features of discordant coastlines of different rock types
How are Caves Arches and Stacks formed
Joints and faults are vulnerable to erosion
Hydraulic action and abrasion widens them which forms a cave
Further erosion of back to back caves breaks through the headland forming an arch
The arch is eroded and weathered eventually collapsing
Which leaves an isolated stack
Further erosion of the stack leads to its collapse leaving a stump
Define longshore drift
The zig zag movement of sediment along the cost caused by waves going up a beach at an angle
What is a spit
A ridge of sand formed by longshore drift
What is an ox-bow lake
a crescent shaped lake formed when a river meander is cut off from the river and isolated
How are meanders formed
As the river gains more velocity, the water is pushed to the outside of the river causing more erosion on the outside bend, which forms a steep river cliff. This is achieved through processes like hydraulic action and abrasion.
How are meanders formed
The current is faster on the outside bend because the river channel is deeper
So more erosion takes place on the outside of the bend forming river cliffs
The current is slower on the inside bend because it is shallower
So eroded material is deposited on the inside bend forming slip off slopes
How do meanders get larger
Over time erosion like abrasion and hyrdaulic action wear down the outside of the meander
How do oxbow lakes form
Erosion causes the outside bend to get closer
Until there is only a small but of land between the bends
The river breaks through this land usually during a flood
And the river flows along the shortest course
Deposition eventually cuts of the meander forming an ox bow lake
