Coasts Lesson 4 (Depositional Features)

Coasts Coasts Depositional FeaturesDepositional Features

Aim: To be able to recognise some Aim: To be able to recognise some features of coastal deposition.features of coastal deposition.

Longshore Drift in actionLongshore Drift in action

Click on picture for a Click on picture for a short video on how short video on how longshore drift occurs longshore drift occurs 2.062.06

Sand and pebble beach with groynes showing how sand has built up against one side of the

groyne.

Direction of drift

1. Beach material almost always moves along the beach in a particular direction which is determined by the prevailing winds. 2. If the winds blow the waves parallel to the shore, sand and pebbles are washed up and back down the beach. 3. If, however, the wind blows so that waves come in at a sharp angle to the coast, the swash carries the pebblesat an angle up the beach. 4. When the backwash moves by gravity back down the beach, the pebbles end up at a different position. 5. This process is repeated and pebbles gradually shift along the beach, a process called longshore drift.

Depositional – BeachDepositional – Beach

Shallow Slope & Shallow Slope & Wide.Wide.

1. Read through information on page 67 then summarise the formation of beaches

Coastal SpitCoastal SpitDirection of wind

Old Headland

Slide 23&24 Slide 23&24 Boardworks - CoastsBoardworks - Coasts

Click this box for animation on spit formation

Coastal SpitsCoastal Spits

• Copy figure 4 – page 67/73 then write an account of how spits form

10 Minute Test10 Minute Test

•Name three features of coastal erosion.Name three features of coastal erosion.

•Name three features of coastal depositionName three features of coastal deposition

•What factor controls longshore drift?What factor controls longshore drift?

Oh No!!Oh No!!

Q. What lies at the Q. What lies at the bottom of the ocean and bottom of the ocean and twitches?twitches?A. A nervous wreck.A. A nervous wreck.