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What causes the longshore drift of sediment particles along the beach?

1 Longshore currents are caused by waves approaching shore at a small angle, moving water parallel to the shore (Steven Earle, “Physical Geology”). The upward-moving water, known as the swash, pushes sediment particles along the beach, while the downward-moving water, the backwash, brings them straight back.

What causes longshore drift?

Longshore (littoral) drift is the movement of material along the shore by wave action. It happens when waves approach the beach at an angle. The backwash (waves moving back down the beach) carries material back down the beach at right angles. This is the result of gravity.

How do the swash and backwash affect the composition of a beach?

If the swash is stronger than the backwash (constructive wave), some of the sediment carried in the wave will be left behind to build up the beach. This means that the beach increases in size. If the swash is weaker than the backwash (destructive wave), very little sediment is carried up the beach.

How does longshore drift move sediment?

The prevailing wind blows waves carrying sediment into the beach at an angle, the waves break on the shore and as the water runs back into the sea it carries the sediment back down the beach, perpendicular to the angle of the shoreline under the influence of gravity.

Which direction does a longshore current flow?

Longshore shore currents travel parallel to the shoreline between the breaker zone and the shore. Along the Oregon and Northern California rocky coasts, the net direction of longshore transport is zero. Down in southern California, the net direction of longshore transport is to the south.

How do currents affect the coastline?

Warm and cold ocean currents can affect the climate of an area along the coast if the winds blow in from the ocean. Warm ocean currents heat the air above the water and carry the warm air to the land, increasing the temperature of the coastal region.

How do engineers decrease the amount of erosion caused by a groin?

How do engineers decrease the amount of erosion caused by a groin? They build more groins and place them parallel to each other along the beach.

What is the difference between longshore current and longshore drift?

What is the difference between longshore current and longshore drift? Longshore current refers to the movement of water, longshore drift refers to the movement of sediment.

What are nearshore currents?

When waves break at an angle to the beach, the momentum of the breaking wave generates onshore currents that flow in the direction of propagation of the breaking wave and its bore. The pile up of water along the shore causes longshore currents that flow parallel to the beach inside the breaker zone.

What is a high rip current?

Rip currents are powerful, narrow channels of fast-moving water that are prevalent along the East, Gulf, and West coasts of the U.S., as well as along the shores of the Great Lakes. Moving at speeds of up to eight feet per second, rip currents can move faster than an Olympic swimmer.

What is a coast that is straight and has marine terraces called?

A coast that is straight and has marine terraces is a(n): emergent coast.

What are the different types of coastlines?

Navigation masterclass: 7 coastline types

  • Glacial landscapes. Steep-sided , clean-edged fjords make for easy navigation but it can be hard to find an anchorage.
  • Rias.
  • Rivers.
  • Barrier Islands.
  • Deltas & Estuaries.
  • Coral Reefs.
  • Volcanic Islands.

What are the two different kinds of coasts?

A cliffed coast or abrasion coast is one where marine action has produced steep declivities known as cliffs. A flat coast is one where the land gradually descends into the sea. A graded shoreline is one where wind and water action has produced a flat and straight coastline.

What are the three main types of shoreline?

The shoreline: between land and sea

  • From cliff to reef. Some parts of the coast are eroded more quickly than others, depending on the type of rock that makes them up.
  • Beaches and marshes. The sand and pebbles produced by the erosion of the rock face accumulate along the coast, forming a beach.
  • Longshore drift.
  • The different types of coast.