LITHOSPHERE CORE COASTLINES 1 BEACHES Beaches are a buffer zone between the waves and the coast. They usually lie between high and low tide marks, but storms can throw material up beyond high tide marks.

LITHOSPHERE CORE COASTLINES 2 The main activity of constructive waves is to deposit pebbles, sand and mud to form a beach. The sea sorts this material into different sizes according to its weight as it moves it about in the water.

LITHOSPHERE CORE COASTLINES 3 LONGSHORE DRIFT On-shore winds make waves approach at an angle ( swash), but they go back down ( backwash) at right angles to the beach. What is the result of this process? Backwash direction Low tide mark Intertidal zone High tide mark Splash zone Swash direction

LITHOSPHERE CORE COASTLINES 4 Q1. Define the terms swash and backwash. A. The swash is the wave motion up the beach away from the sea, and the backwash is the wave motion down to the sea again. Q2. Why do the waves not travel up and down at the same angle? A. An off-shore wind or sea current forces the waves onto the beach at an angle. Gravity makes them return at right angles to the sea.

LITHOSPHERE CORE COASTLINES 5 Q3.What is the overall result of this action? A. The material moves along the coastline in the direction of the wind/ current. Q4.How do people attempt to stop this movement? A.Structures called groynes are built at intervals along the beach to stop material travelling all along the coast. The material is periodically moved back to where it came from, usually by bulldozers.

LITHOSPHERE CORE COASTLINES 6 How do Sand Spits form? Longshore drift moves large amounts of material along the beach until there is a sudden change in the direction of the coastline. The sand keeps on moving in the original direction, even though there is not a coastline to follow. The sea has to be relatively shallow and sheltered allowing the accumulation of sand usually beyond a headland. Sometimes a curve develops if the on- shore wind changes direction. Spits can become permanent if the prevailing wind picks up sand and blows it inland forming sand dunes.

LITHOSPHERE CORE COASTLINES 7 Hurst Spit in Hampshire is an example that you can quote in the exam.

LITHOSPHERE CORE COASTLINES 8 On page 289 of WIDER WORLD there is a diagram to copy; fig HURST SPIT, HAMPSHIRE

LITHOSPHERE CORE COASTLINES 9 How Do Bars and Lagoons form? A bar is a barrier of sand stretching right across a sheltered bay. It usually stretches across the bay due to the absence of any large river that might wash it away. It can cut off a lagoon to the landward side. A lagoon is a body of brackish water- part salty, and part fresh. It often supports specialised plants and animals, and is protected as a nature reserve..

LITHOSPHERE CORE COASTLINES 10 This spit will become a bar if it reaches the other side of the estuary. Can you work out the direction of longshore drift?

LITHOSPHERE CORE COASTLINES 11 If a bar links up with an off-shore island, it creates a tombolo. Chesil Beach- one of the most famous bars in the UK has a tombolo called Portland Bill. Chesil beach from Portland Bill; the shingle is 29kms long. bar tombolo

LITHOSPHERE CORE COASTLINES 12 ORDNANCE SURVEY MAPWORK You need to be able to recognise coastal deposition landforms from a map. To practice this skill, take a copy of the question sheet and the two O.S. maps and tackle the questions. THEY ARE NOT ALL EASY !! 7

LITHOSPHERE CORE COASTLINES 13 As you go through the next revision slide, for each feature mentioned, look back through your textbooks and this presentation. You are looking for named examples of as many features as possible. Perhaps you could work in pairs to do this task!

LITHOSPHERE CORE COASTLINES 14 You have now completed the deposition section. You should be familiar with the following terms and be able to define and use them in your answers. BEACH BAY BAR SPIT TOMBOLO HEADLAND SORTING GROYNE LONGSHORE DRIFT LAGOON SALT MARSH SHINGLE SWASH BACKWASH ON-SHORE WIND

LITHOSPHERE CORE COASTLINES 15 Now watch the video- tape 36 number 3; [ stop after the narrator starts to talk about human intervention in coastal features- you will see the rest of the video when we learn about the case studies of coastal management in the Rural Land Resources Application ] REVISION TIME ! Erosion and deposition features