formation of erosional and despositional landforms

describe the formation of headlands and bays

Headlands and bays form on discordant coastlines due to differential erosion of alternating bands of hard and soft rock. Softer rock is eroded more quickly by wave processes such as hydraulic action and abrasion, forming bays, while more resistant rock remains as headlands. As waves approach the coastline, they slow in shallower water at the headlands, while remaining faster in deeper water in the bays. This causes wave refraction, bending wave fronts towards the headlands and concentrating energy there, increasing erosion. In contrast, wave energy is reduced in the bays, leading to deposition and the formation of beaches.

describe the formation of coves

A cove forms on a concordant coastline where a weakness such as a joint or fault in the resistant outer rock is exploited by wave processes like hydraulic action and abrasion. This weak point is gradually enlarged until the waves break through the hard rock layer. Once breached, the softer rock behind is exposed and erodes much more rapidly, causing the coastline to retreat inland and form a circular-shaped inlet known as a cove.

describe the formation of a wave cut platform

The cliff is weakened by sub-aerial processes such as freeze-thaw weathering, which exploits cracks in the rock. At the base of the cliff, hydraulic action and abrasion concentrate erosion, forming a wave-cut notch. Continued undercutting enlarges the notch, creating an overhang of unsupported rock. Eventually, the overhang becomes unstable and collapses due to gravity. Repeated cycles of undercutting and collapse cause the cliff to retreat inland, leaving behind a gently sloping wave-cut platform that is further widened and smoothed by wave action over time.

the wave cut platform is uneven due to differential erosion

describe the formation of caves arches tacks and stumps

Cracks and joints in a headland are exploited by wave processes such as hydraulic action and abrasion, and are further weakened by weathering processes including salt crystallisation, wetting and drying, and freeze-thaw. These cracks are enlarged into caves. Wave refraction concentrates wave energy on the headland, increasing erosion so that caves on either side may deepen and eventually meet to form an arch. Continued sub-aerial weathering weakens the roof of the arch until it collapses under gravity, forming a stack. The stack is then further eroded at its base by wave action and weakened by weathering, eventually collapsing to form a stump.

explain the formation of beaches

Beaches form when sediment such as sand and shingle is deposited along the coastline. Deposition occurs when waves lose energy, often in sheltered bays where constructive waves dominate. Constructive waves have a strong swash and weak backwash, which moves more sediment up the beach than is removed. Over time, repeated deposition causes sediment to accumulate, forming a beach.

explain what storm beaches are and how they form and also what berms are

storm beaches are deposited by waves in storms and large waves throw heavy pebbles high up on the beach and it builds up on the back of the beach

berms are a series of small ridges that form near the high tide mark so they are raised ridges of sand and shingle and form by deposition by swash

explain the formation of spits

A spit forms when longshore drift transports sediment along the coast as waves approach at an angle. Sediment is moved along the beach by the swash and returned straight down by the backwash. Where the coastline changes direction or meets an estuary, wave energy decreases and deposition occurs. Over time, deposited sediment builds out from the coast to form a narrow ridge of sand or shingle called a spit, often with a recurved end due to changes in wind and wave direction.

explain what and how tombolos are formed

A tombolo forms when longshore drift transports sediment along the coast. As waves move around an offshore island, wave refraction causes wave energy to decrease in the sheltered area behind it. Sediment is deposited in this low-energy zone and gradually builds up. Continued deposition eventually creates a ridge of sand or shingle that connects the island to the mainland, forming a tombolo.

explain the formation of barrier beaches

a barrier beach is a long narrow ridge of sand that runs parralell to the coastline and is not connected to the mianland

no one is set on the formation of barrier beaches but one theory for the formation is a previosu spit that has stretched out to sea and the area around the proximal ppoint has been eroded by the sea leaving a detached ridge off shore

barrier beaches protect the coastline by absorbign wave energy

explain the formation of sand dunes and explain the different dunes and talk about the vegetation coverage and order of formation

• for sand dunes to form, a large wide beach needs to be present and a also a large supply of sand

• when the sand is blown to the back of the beach by aeolian processes such as saltation, the sand accumulates around an obstacle such as drift wood and more sand builds up

• this process continues until an embryo dune is formed

• the embryo dune then inhibits vegetation which stabilises the dune and allows more sand to grow

• it then form sinto a fore dune and a new embryo dune can from infront

• the sand dune continues to grow into a yellow dune, grey dune and then a mature dune

• the mature dune is the most stable and most covered in vegetation which then trees can grow such as oak and ash

explain the formation of salt marshes

• as tidal currents slow, they begin to deposit material and leads to the grow of eel grass in submerged areas and this aids deposition and slows the current further

• gradually, uneven mudflats develop at low tide and become colonised by pioneer plants develop on the mud flats and a dense mat is created which creates friction to slow the currents further leading to more deposition occuring.

• the build up of sediment starts to build up the mudflat and evetually rising above sea level and by this stage the upper levels of the marsh are rarely covered by the sea