Edexcel River Processes

_______________ action - This is the sheer power of the water as it smashes against the river banks. Air becomes trapped in the cracks in the rock of the river bank and bed, and causes the rock to break apart.

• Saltation

• Hydraulic

• Abrasion

__________________ - When pebbles grind along the river bank and bed in a sand-papering effect.

• Weathering

• Abrasion

• Hydraulic

___________________ - When rocks that the river is carrying knock against each other. They break apart to become smaller and more rounded.

• Attrition

• Abrasion

• Solution

__________________ - When the water dissolves certain types of rocks, eg limestone.

• Solution

• Weathering

• Erosion

________________ Weathering– rainwater is slightly acidic and over time this wears away the rock.

• Chemical

• Biological

• Freeze-Thaw

____________________ Weathering- occurs when plants and animals wear away rocks, for example, roots growing in cracks in the rock or animals such as rabbits burrowing into rock.

• Freeze Thaw

• Chemical

• Biological

physical changes causes rocks to break down, for example, a change in temperature from day to night causes rock to expand and contract and break up (eg onion skin weathering). Or, changes in temperature cause water to freeze and expand, melt and contract leading to __________________________weathering.

• Biological

• Freeze-Thaw

• Chemical

___________ are occasional, rapid movements of a mass of earth or rock sliding along a steep slope. They can occur after periods of heavy rain, when the water saturates overlying rock, making it heavy and liable to slide.

• Landslides

• Waterfalls

• Mass Movement

_________ creep is a very slow movement, occurring on very gentle slopes because of the way soil particles repeatedly expand and contract in wet and dry periods. When wet, soil particles increase in size and weight, and expand at right angles. When the soil dries out, it contracts vertically. As a result, the soil slowly moves down slope.

• Rock

• Soil

• River

______________- large, heavy pebbles are rolled along the river bed. This is most common near the source of a river, as here the load is larger.

• Suspension

• Solution

• Traction