Coasts Flashcards
(39 cards)
Weathering
Exposed rocks along a coastline are broken down by weathering.
Three types of weathering
Physical, Biological, chemical
Freeze-thaw weathering
Freeze-thaw weathering occurs when the rocks are permeable or porous. The water enters, freezed and expands, melts and the water goes deeper, and repeats until rock splits
Biological weathering
Roots enter small crack in the rocks, at roots grow and the crack expands, rocks break away
Chemical weathering
Softer rocks can be dissolved by acids in the water
Coastal Processes
Erosion, Transportation, Deposition
Two types of waves
Destructive, constructive
Destructive waves
Weak swash, strong backwash. Removes material from the beach. Steep and close together (high wave frequency)
Constructive waves
Strong swash and weak backwash. Builds up the beach. Low wave frequency
Types of Erosion
Hydraulic action, abrasion, attrition, corrosion
Hydraulic action
the power of the wave forces water and air into cracks, pressuring the rock to split apart
Abrasion
Waves pick up rocks from the seabed and throw them at the cliff
Attrition
Rocks in the sea knock against eachother: they break apart to become smaller and rounder
Corrosion
salts or chemicals in the water act to dissolve the rocks they touch
4 types of Transportation
Solution, suspension, saltation, traction
Solution
When minerals are dissolved in sea water- load is not visible
Suspension
Small particles like clay and slits are suspended in water flow
Saltation
Small pieces of rock or shingle are bounced along the sea bed
Traction
where pebbles and larger material are rolled along the sea bed
Longshore drift
The moving of sediment along the coastline. Waves approach at an angle and then the backwash brings the material straight back down the beach. This causes longshore drift
Landforms of coastal erosion
Headlands and bays, cliffs wave-cut notches and platforms, caves arches stacks and stumps
Headlands and Bays
Discordant coastlines with different types f rocks erode at different paces. Soft rocks (limestone, clay) erode faster creating a bay, while harder rocks take longer, forming headlands
Ciffs, Wave-cut Notches, and Wave-cut Platforms
The base of the cliff erodes in to an undercut, called a wave-cut notch. Overtime the cliff collapses as nothing is holding it up. Where the cliff previously was is now a wave-cut platform
Caves
Waves erode a crack in a headland. This crack, overtime, become larger and deeper to form a cave