Depositional Features Flashcards
What is a barrier beach?
Barrier beaches are narrow, low-lying strips of beach and dunes that are roughly parallel to the coastline and are separated from the mainland by a body of water or wetland.
What is a psammosere?
A vegetation succession that originates on sand at the coast.
What is a recurved spit?
A spit whose outer end in turned landward by current deflection, by the opposing action of two or more currents, or by wave refraction; a hook.
What is a spit?
A spit is an extended stretch of beach material that projects out to sea and is joined to the mainland at one end. Spits are formed where the prevailing wind blows at an angle to the coastline, resulting in longshore drift. They can also be formed due to a change in direction of coastline.
What is a Tombolo?
A deposition landform in which an island is attached to the mainland by a narrow piece of land such as a spit or bar. Once attached, the island is then known as a tied island.
What is Bar?
It is a ridge of sand or shingle which forms across the mouth of a river, the entrance to a bay or harbour. It is usually parallel to the coast.
What are Berms and how are they formed (wave type and location)?
Small ridges that develop at the position of the mean high tide mark resulting from deposition at the top of the swash. Berms are generally created by smaller waves which have less energy so the material is smaller.
What is alluvium and where does it come from?
Alluvium is loose, unconsolidated (not cemented together into a solid rock) soil or sediments, which has been eroded, reshaped by water in some form, and redeposited in a non-marine setting.
What is Till?
Unsorted material deposited directly by glacial ice and showing no stratification (arrangement). Till is sometimes called boulder clay because it is composed of clay, boulders of intermediate sizes, or a mixture of these.
What are Cuspate Forelands/Barriers?
Cuspate forelands, also known as cuspate barriers or nesses, are geographical features found on coastlines and lakeshores that are created primarily by longshore drift. Formed by accretion and progradation (seaward shift of material caused by deposition) of sand and shingle, they extend outwards from the shoreline in a triangular shape.
When does coastal deposition occur?
When waves lose energy or when large inputs of sediment are made into the coastal system.
Where are depositional landforms common?
Depositional landforms are produced on coastlines where sand and shingle accumulate faster than they are removed. This normally occurs in areas of coastline dominated by constructive waves of low energy.
State and explain the differences between different beach profiles (sand and shingle).
Sand produces beaches with a gentle gradient; usually less than 5 º. This is because its small particle size means that it becomes compact when wet, allowing little percolation during backwash. Shingle produces steeper beaches; often 10-20º. Shingle may make the upper part of the beach, where rapid percolation due to larger air spaces means that little backwash occurs and so material is left at the top.
State and explain the factors affecting beach profile/type (waves).
Wave Energy: High energy waves tend to produce shingle beaches. Sandy beaches are found in low energy areas.
Wave Type: Destructive waves = stronger backwash = more material moving back down the beach = shallower profile. Constructive waves = strong swash = more material moved up the beach = steeper beach profile.
How are sand dunes formed?
Dunes are landforms formed from sand deposits that have been blown off the beach. Where sufficient sand is deposited and dries in the intertidal zone (foreshore – area between the high and low tide marks) it is then transported by saltation by the blowing wind. Sand dunes only form where the rate of beach deposition is greater than erosion (positive sediment budget).
