Geography Rivers and Coasts Paper 1.

Describe how waves form.

1. wind blowing over the ocean creates friction with the water surface causing ripples to form.

2. Faster moving ripples merge with slower ones. Waves become bigger and more organised.

3. The longer the waves travel for, the larger and more organised they become

What is backwash?

movement of the wave down the beach

What is swash?

movement of the wave up the beach

Describe the features of a constructive wave.

• wave crests are far apart

• wave spills forward

• gentle sloping wave front

• strong swash and weak backwash

• results in gentle beach

Describe the features of a destructive wave.

• wave crests are close together

• steep wave front

• wave plunges downwards

• strong backwash which pulls pebbles and sand out to sea

• results in steep beach

What is weathering?

The breaking down of rocks by mechanical, chemical or biological processes.

What is freeze thaw action?

• mechanical weathering

• where rain fills up in cracks in rocks, freezes overnight and expands which pushes the crack outwards

What is mechanical weathering?

The break up of rocks by physical force.

e.g. freeze thaw and biological weathering

What is biological weathering?

weathering when living things like animals and plants burrow into a crack which eventually weakens the structure.

What is chemical weathering?

Where rainwater which contains carbon dioxide, reacts with the calcium carbonate in rocks such as limestone and chalk. This dissolves and is washed away in the solution, weakening the rock.

What are the types of mass movement?

• mudflows

• rockfalls

• landslides

• rotational slip

What is rockfall?

• fragments of rock break away from the cliff face often due to freeze thaw weathering. 

• piles of rock called scree form at the bottom

What is a landslide?

Where blocks of rock slide downhill because the bedding of the rock sloops downwards and makes it more likely that large blocks will shear out.

What is a mudflow?

• soil or weak rock becomes saturated

• occurs on slopes over 10 degrees tilt

• rapid sudden movement occurs when there is not enough vegetation to hold the soil in place.

What is rotational slip?

• occasional rapid movement of a mass of earth or rock sliding along a concave plane. They can occur over periods of heavy rain, when the water saturates overlaying rock, making it heavy and liable to slide.

What do processes end in?

ION

e.g. 

erosion

abrasion

solution

What are the processes or erosion?

• hydraulic action

• abrasion

• attrition

• solution

What are the processes of transportation?

• traction

• saltation

• suspension

• solution

What is erosion?

The process of seawater wearing away land

What is hydraulic action?

• type of errosion

• The power of the waves as they smash against the cliff

• trapped air is forced to make holes in the rock

• this forces the rock to eventually break apart

What is corrasion?(abrasion)

type of erosion

fragments of rock, pebble and sand are picked up by waves and hurled at cliffs, acting is sandpaper

What is attrition?(it doesn’t wear the cliff down)

type of erosion

Where rocks and pebbles under the water knock against each other continuously, which chips fragments off.

What is solution?(corrasion)

type of erosion

acids in the seawater erode rock.

What is suspension?

type of transportation

particles are suspended in the flow of the water

What is solution?

• type of transportation

• rocks are being transported as dissolved chemicals, often from chalk

What is traction?

Type of transportation

large pebbles are rolled along the seabed by currents

What is saltation?

Type of transportation

Currents lift up pebbles which bounce along seabed.

What is deposition?

Where sediment is dropped due to less wave energy.

What is long shore drift (LSD)

1. pebble moves up the beach at an angle due to swash

2. backwash carries the pebble down the beach at a straight line

3. this happens continuously at the general direction of the prevailing wind.