8.5 TRANSPORT AND DEPOSITION Flashcards
what is long short drift?
-wave crests approach beach at an angle
-swash carries material up beach
-backwash carries materials back down the beach at right angles
-as a result of gravity
-this process slowly moves sediment across the beach
what is traction?
-sediment rolls along pushed by waves and currents
what is saltation?
-sediment bounces along either due to force of water/wind
what is suspension?
-sediment carried in water column
what is solution?
-dissolved material is carried in water as a solution
what are currents?
-flows of seawater in a particular direction driven by winds/ differences in water density
when does gravity settling occur?
-when the energy of transporting water becomes too low to move sediment; large sediment will be deposited first followed by smaller sediment
when does flocculation occur?
-depositional process that’s important for small particles, such as clay which are so small they remain suspended in water
-clay particles clump together due to electrical attraction and become large enough to sink
what is a spit?
-sand beach ridge extending beyond a turn in coastline (greater than 30 degrees)
-Long short drift current spreads out and loses energy leading to deposition
-Length of spit is determined by existence of secondary currents causing erosion
What’s a bayhead beach?
-swash-aligned feature where waves break at 90 degrees to shoreline and move sediment into bay where beach forms
-erosion is concentrated onto headlands and bay is now area of deposition
what is a tombolo?
-sand or shingle bar that attaches the coastline to an offshore island
-form due to wave refraction around an offshore island that creates area of calm water and deposition between the island and coast
what is a barrier beach?
-sand/shingle beach connecting 2 areas of land with a shallow water lagoon behind
-can occur when spit grows long that it extends across a bay
what is a hooked/ recurved spit?
-spit whose end is curved landward into a bay
-seaward end of spit naturally curves landward into shallower water
what is a cuspate foreland?
-roughly triangular-shaped features extending out from a shoreline
what are the sources for a sediment cell?
-where sediment is eroded from the cliffs
-they can be offshore bars
what are the transfer zones in a sediment cell?
-places where sediment is moving along coast by long short drift and offshore currents
what are the sinks in a sediment cell?
-locations where the dominant process is deposition
what do negative feedback mechanisms do?
-they help maintain the balance by pushing the system back towards equilibrium
