Coastal Systems and Landscapes Revision

Shingle beaches

Steep and Narrow. They're made up of larger particles, which pile up at steep angles

Sand beaches

Formed from smaller particles, are wide and flat.

Distinctive Features of Beaches

Berms, Runnels, Cusps

Berms

Ridges of sand and pebbles found at high tide marks

Runnels

Grooves in the sand running parallel to the shore, formed by backwash draining to the sea.

Cusps

Crescent-shaped indentations that form on beaches of mixed sand and shingle.

How are beaches formed?

Constructive waves deposit sediment on the shore.

How are spits formed?

The tend to form where the coast suddenly changes direction. Longshore drift continues to deposit material across the river mouth, leaving a bank of sand and shingle sticking out into the sea.

Types of spit

Simple, Recurved-end spit, Compound spit.

How are bars formed?

A spit joins two headlands together. This can occur across a bay or across a river mouth.

How are offshore bars formed?

A bar is formed off the coast when material moves towards the coast. These may remain partly submerged by the sea.

What is a tombolo?

A bar that connects the shore to an island (often a stack)

What are Barrier Islands/Beaches?

Long, narrow islands of sand or gravel that run parallel to the shore and are detached from it.

How are Barrier Islands Formed?

-They may have formed after the last ice age ended, when ice melt caused rapid sea level rise. The rising waters flooded the land behind beaches and transported sand offshore, where it was deposited in shallow water, forming island.

How are sand dunes formed?

Sand deposited by longshore drift is moved up the beach by the wind. It is then colonised by vegetation which stabilises the sand and causes more to accumulate.

Eustatic Change

Caused by a change in the volume of water in the sea, or by a change in the shape of the ocean basins

Increased Temperature effect on eustatic change

Causes melting of ice sheets, which increases sea level. It also causes water to expand, which increases sea level further.

Decreased Temperature effect on eustatic change

Causes more precipitation to fall as snow. This increases the volume of water stored in glaciers and so reduces the volume of the sea, which decreases sea level.

Isostatic sea level change

Caused by vertical movements of the land relative to the sea. Any downward movement of the land causes the sea level to rise locally, while uplift of land causes sea level to fall.

How accumulation or melting of ice sheets effects isostatic change

Uplift or depression of the Earth's crust. Slow uplift of land can continue for thousands of years after the weight of a retreating glacier is gone

The Four Options of Coastal Management

- Hold the Line
- Advance the Line
- No Active Intervention
- Managed Realignment

Shoreline Management Plans

The coastline is split into sediment cells. For each cell, a plan is devised for how to manage different areas with the aim of protecting important sites without causing problems elsewhere in the sediment cell.

Integrated Coastal Zone Management

Considers all elements of the coastal system where coming up with a strategy. It aims to protect the coastal zone in a relatively natural state, whilst still allowing people to use and develop it in different ways.