Geography paper 1

Definition of weathering

Weathering is the decay or crumbling of rocks in their original place on, or close to, the ground surface. Mostly caused by weather factors like rainfall and temp change

What are tge 3 types of weathering

Mechanical (physical)

Chemical

Biological

Define mechanical weathering

The break up of rocks. Where this happens, piles of rock fragments called scree can be found at the foot of cliffs

Define chemical weathering

Caused by chemical changes. Rainwater, which is slightly acidic, very slowly dissolves certain types of rocks and minerals

Define biological weathering

Due to the actions of flora and fauna. Plant roots grow back into cracks in the rocks. Animals like rabbits burrow into weak rocks such as sands

Define mass movement

Is the downward movement of material under the influence of gravity.

What are the 3 types of mass movements

Sliding

Slumping

Rock falls

Define sliding

Large blocks of rock slide down the cliff face as a landslide, often triggered by earthquakes or heavy rainfall

Define slumping

Known as slipping, involves the collapsing of statutes or weak rocks (like sand and clay), often along a curved surface

Freeze thaw

Freeze thaw is a mechanical weathering process.

Water goes into cracks of the rocks and freezes and expands and makes the crack of the rocks bigger. Then when water thaws and freezes over time, fragments of rock may break off and fall to foot of cliff (scree)

What is a hydrograph?

The volume of water flowing along a river is its discharge. Measured in cumecs (cubics metre per second). A hydrograph is a graph that plots river discharge after a storm. It shows how river discharge rises after a storm then returns to normal

What is lag time?

Time in hours between the highest rainfall and the highest discharge of the river. Shows how quickly water is transferred into a river channel. Shorter lag time, larger flood risk

Why do some hydrographs have short lag times and high peaks

Impermeable rocks encourage rapid overland flow

Urbanisation causes rapid water transfer

Small basins lead to rapid water transfer

Steep slopes (relief) lead to rapid water transfer

Rainfall intensity

Why are some hydrographs flat and have low peaks and larger lag times

Large basins lead to slower water transfer Small

Permeable rock surfaces encirage slow water transfer by groundwater flow

Forest slow don water transfer because of interceptions

Gentle slopes (relief) slow down water transfer because

Light rain intensity