Coasts EQ 1 Part 3 Flashcards
How are notches formed?
- waves repeatedly pound against the rock surface
- weakens the rocks through erosional processes (hydraulic action and abrasion)
- A crack or joint on the rock surface will gradually enlarge due to the erosional processes -> notch.
How are cliffs formed
roof of the cave becomes unstable with further erosion, and eventually collapses into the sea, forming a steep cliff. The collapsed material will be deposited at the foot of the cliff.
define cliff
A cliff refers to a steep and near- vertical rock surface found along coasts.
How are caves fomed?
notch may be further eroded to form a bigger hollow space called a cave.
Some coasts are made up of rocks with different levels of resistance. How do the 2 types coexist? and what happens during erosion to them?
Resistant rocks, such as granite, may occur in alternate bands with less resistant rocks, such as shale. The rocks form bands at right angles to the coast, which exposes them to continual wave erosion.
What is a wave-cut platform?
a gentle sloping platform appears at the base where the cliff used to be. This platform is called a shore platform/ wave-cut platform, which is submerged during high tides.
how are wave-cut platforms formed?
- Some of the materials may be carried by waves and thrown against the base of the cliff
- undercutting the cliff through the process of abrasion.
- the cliff will retreat inland and a gentle sloping platform appears at the base where the cliff used to be.
another word for wave-cut platform?
short platform
how are cliffs formed? give me the 3 steps.
notch - cave - cliff
Resistant rocks are less likely to erode and stay as?
Headlands which extends outwards into the sea
what happens to less resistant rocks which are easier to erode?
They erode away to form bays.
wave erosion along such coastlines cannot carry on indefinitely. SO what happens next?
The rate of erosion in the bay will eventually decrease as wave energy decreases with the refraction of the wave front by the headlands.
How does wave refraction happen?
Waves bend because of changes in wave speeds, causing wave energy to spread unevenly along the coast and impacting different areas to varying degrees.
what is wave refraction?
Wave refraction is the process by which waves change direction as they approach a coast.
what do waves tend to do on coastlines with alternating headlands and bays? and what does this result in?
[FOR HEADLANDS]
waves tend to converge on headlands - increased wave high and greater erosive energy
What do waves do when approaching bays?
waves diverge - decrease in wave hight and reduced erosive energy
What are the 2 common wave erosion that erodes headlands?
- hydraulic action
- abrasion
what are commonly found on a headland?
- caves
- arches
- stacks
how to forms stack?
the roof of the arch may collapse, leaving behind the pillar of the arch on the seaward side known as the stack.
what do waves erosions form in headlands and how ?
Wave erosion, especially by hydraulic action and abrasion, erodes the headland along a line of weakness such as joint and fault. Continuous wave erosion results in the formation of a cave in the area.
how to form an arch?
two caves develop on the opposite sides of a headland, erosion may eventually join the two caves together to form an arch.
how to form a spit?
- Longshore currents transport sediments parallel to the coast.
- longshore drift continues in the original direction when the coastline changes.
- Over time, materials accumulate above the water surface.
- This forms a spit, a narrow ridge of sand or pebbles, with one end attached to mainland.
how to form a stump?
Continued erosion reduces the stack to a lower level to form a stump, which is usually covered during
high tide and exposed during low tide.
what is a tombolo?
a spit that extends seawards and joins an offshore island nearby to form a tombolo.
