beach profiles

Beach Profiles

AS Geography

Learning Objectives

• Understand that beaches contain different landforms created by deposition

• Look at the associated features of beaches

• Understand the key terms and factors that dictate how each feature is formed

What is a beach Profile?

• What can you tell me about beaches?• The are full of sediment• They constantly change• They are a store of inputs• They are the source of outputs• They are buffer between the land and the

sea

Most Beaches have 3 main components

• Nearshore• Foreshore• Backshore

Nearshore

• What factors affect the nearshore

Nearshore

• Zone extending seaward of the shoreline well beyond the breaker zone. Zone in which nearshore currents occur.

• The gentle gradient results from the smoothing out of sediment associated with the back and forth movement of the waves

• Due to the loss of energy, some sediment can be deposited in sand bars

Foreshore

• What factors affect the foreshore?

Foreshore

• Once a wave breaks, its water moves as a sheet upslope as swash, and falls back toward the sea as backwash. The narrow area in which this occurs is called the swash zone.

• The location of swash zone shifts due to the rising and falling of the water level, associated with tides.

• The area affected by the swash zone on a daily basis is called the foreshore (between low and high tide marks)

• As the flow of swash slows (and eventually stops) in its upper reaches, some of the sediment carried by the water can be deposited.

• But much of the sediment is returned back down to the upper shoreface due to backwash.

Describe the changing characteristics of the storm beach from SW to NE. (7 marks)

Backshore

• What effects the backshore?

Backshore Zone

• Beyond the Foreshore is a backshore zone, characterized by dunes.

• Sediment can also be transported to the backshore area during storms, when big waves can reach far inland.

The features

Berms • A nearly horizontal or landward-sloping portion of a beach,

formed by the deposition of sediment by storm waves

Ridges and Runnels

• Ridges are areas of the foreshore that are raised above the adjacent shore which dips into a Runnel. The cross-section is similar to that of hills and valleys.

• Ridge and Runnel Systems are formed due to the interaction of tides, currents, sediments and the beach topography. They will only form on shallow gradient beaches

Cusps

• Beach cusps are rhythmic shoreline features formed by swash action

• They develop in a variety of environments but commonly on coarse-grained beaches with low wave energy

Spits

• long narrow ridges of sand and shingle which project from the coastline into the sea.

• They begins due to a change in the direction of a coastline - the main source of material is from longshore drift

• Where there is a break in the coastline and a slight drop in energy, longshore drift will deposit material at a faster rate than it can be removed and gradually a ridge is built up, projecting outwards into the sea

Bars

• A bar may form where there a changes in coastal direction and drop in tidal energy creating sedimentation

Using pages 93 to 96 answer these questions:

• Distinguish between a spit, bar and tombolo

• Outline three pieces of evidence that indicate the direction of longshore drift along a coastline.

• Using an example(s), describe the main features of a spit. (Draw annoted sketch)

• Choose either a beach or a spit. Describe the chosen landform and explain the role played by longshore drift in its formation