Landforms of Coastal Deposition Flashcards

All 7 cards in this deck

Where on a bay does a beach usually form, and why?

At the head (innermost part) of the bay, where wave action is weakest so deposition occurs.

What is a spit?

A sand or shingle beach joined to the land at one end but projecting out (downdrift) into the sea, often with a recurved end.

Where do spits begin to form?

Where the coastline suddenly changes shape or at a river mouth/estuary, with material building up in the sheltered lee.

What is a bar?

A ridge of deposited material that grows right across a bay by longshore drift, often trapping a freshwater lagoon behind it.

True or false? A spit grows all the way across a river estuary.

False. River currents carry material seaward, so the spit cannot grow right across the estuary.

How do sand dunes form?

Onshore winds carry dry sand inland from the beach. An obstacle (such as a plant or debris) slows the wind so the sand is dropped and piles up. Plants like marram grass then grow on it, binding the sand so the dune grows.

Why are shingle beaches steeper and narrower than sand beaches?

Swash soaks into the gaps between large pebbles, so the backwash is weak and leaves them piled up in a steep bank. Sand is fine and stays wet, so the backwash runs off it and drags grains back down, spreading a wide, gentle beach.