Revision:Beach Materials

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Most beaches of composed of rock breakdown with varying proportions of biological material usually shell fragments. However if its an accumulation of material at the high tide mark the following may be included;

1. Canada-timber beach
2. USA-tin can beach

A beach may be a store in a bay or a mobile stream along the coast.

Four Sources of Beach Material

1. Material eroded from headlands dependant on the rock type. Easily eroded bolder clay resistant to erosion is granite.
2. Sediment moved up onto the beach from the offshore zone material is washed up from the seabed.
3. Large rivers carrying material from inland to the sea mainly silt and clay.
4. Material cycled from one beach along the coast to another.

Beach Materials

1. Sand material 2mm.
2. Pebbles 4mm-64mm.
3. Unusual to have much 2mm-4mm.
4. Unusual to find a mixture of sand and pebbles.

Sand Beaches

Usually have a gentle gradient and a small particle compact when wet restricted. The courser the sediment the steeper the beach. Exposed beaches are gentle and sheltered beaches are steep. They have a strong swash therefore pushing material up the beach and they have a weak backwash so less material is carried down the beach.

• Beach Face - is the sharp break of slope that the zone affected by the high tide wave action.
• Berm - is a horizontal gently inclined area at the top of the beach which experiences frequent wave action.
• Summer profile of a sand beach is usually higher than a winter one in winter storms erode the beach in summer the beach is built up.
• On Shore Winds - are winds blowing onto shore steep waves this occurs in more erosion. Britain's prevailing wind is from the west south west so on the east coast less erosion takes place.
• Steep Waves - have a strong backwash and moves material back down the beach, which then accumulates at the breakpoint.

Ridge and Runnel Beaches

Are in a macrotidal environment with a limited fetch they occur on sand beaches and the sand is moved up into mounds 100m-200m from the crest and the crest is up to 1m in height. Runnel is the depression between rudges and water collects in the runnel and cuts channels through the ridge at a low point.

Shingle Beaches

They are sorted by size according to the waves the larger the shingle the steeper the gradient. Large spaces occur between the pebbles and therefore more peculation occurs and there is a weaker backwash and very little shingle is moved back down the beach. A strong swash occurs and this transports material up the beach forming a berm at the spring high tide mark. Above the berm occurs a storm beach.

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