Landforms Flashcards
How is a beach formed?
Sediment is deposited by constructive waves.
Longshore drift brings sediment from erosional sources.
How is an offshore bar formed?
Long ridge of sand/pebbles formed offshore when destructive waves break before reaching the beach. Waves scour the seabed and throw materials forward into a heap. Sea currents also supply sediments.
How is a barrier beach formed?
Beach that connects 2 areas of land, lagoon forming behind. Forms with a plentiful supply of sediment, shallow nearshore and offshore areas, waves with enough energy to move sediment and a rising sea level to push sediment -> shore.
How is a nearshore bar formed?
Similar to barrier beaches but smaller. Commonly formed in the surf zone where storm waves break, scooping up sediment and adding them to onshore transport, to pile them up in a longer ridge, parallel to the coast.
How does a tombolo form?
After longshore drift carries sediment across a gap between the mainland and an island, forming a narrow low ridge of sediment.
How is a spit formed?
Formed when there is a dominant main longshore drift direction, plenty of sediments from mass movement and erosion and the gap in the coastline.
Sediments are transported along the coast. When they reach the gap in the coast. They are carried for a short way in the same direction until they are deposited on the seabed.
Overtime sediment is deposited so that a narrow strip of land forms across the gap.
The shelter provided by the spit means that sediment is deposited behind it to form mudflats where a salt marsh can develop.
As the spit grows, the tides, river occurrence and other wave directions turn the end of a spit into a hook ‘recurved spit’.
How is a double spit formed?
Double spits, may form where there are local variations in longshore drift and strong river currents, spits form on either side of a large bay, but do not join as river currents pass out into sea between the spits.
How are cuspate forelands formed?
Low-lying roughly triangular, headland that probably develops when longshore drift from 2 opposite directions, forms, two spits across a bay. These meet and shelter the bay behind them, which fills the sediments, mudflats and salt, marsh form, and deposition forms lowland area.
