What is a tributary
A stream or small river that joins a larger stream or river
Where is the mouth of the River
At the bottom the point where the river flows into the sea
What’s weathering
The breakdown and decay of rocks by natrual processes acting on the river valleys sides
Difference between weathering and erosion
Erosion- wears rock away and it moves
Weathering- breaks down rock in the same place rock isn’t moved
What’s mechanical weathering (freeze thaw)
When rainwater enters cracks or gaps in rock and freezes if temp is below zero the water then expands into ice and puts pressure on the rock causing it to break up into smaller peices
What’s chemical weathering
As the rain is slightly acidic it falls and reacts with certain rocks which causes the rock to break up and disintegrate
What’s biological weathering
Seeds that get in rocks can start to grow when moisture is present the roots over time grow through cracks in rocks and split the rock apart
Examples of mass movements
Soil creep
Sliding
Flows
What is a mass movement
The movement of rocks and soil downslope due to gravity helped by weaker rocks, steep slopes and rainfall
What’s soil creep (type of mass movement)
When soil particles slowly fall down a slope
What’s sliding ( a mass movement)
Where material moves rapidly down a slope in one go eg. Landslide
What are flows (type of mass movement)
Where masses of soil or rock mixed with water flow downhill like a liquid
What does river erosion erode
The valley bottom and sides of the river
When do rivers drop rocks
When they loose energy further down the river
When do rivers have more energy
When there is a greater volume of water
What’s hydraulic action
When the sheer force of water hitting the river bed and banks erodes sediment away
What’s abrasion
When material in the water rubs away the river bed and bank wearing it away
Most common type of river erosion
Abrasion
What’s solution
River water is slightly acidic so can dissolve some rocks and minerals
What’s attrition
When sediment particles in the river collide with each other causing edges to be knocked off
What’s transportation in a river
When it picks up sediment and carries it downstream
What’s traction (form of river transportation)
Rolling Stones along the river bed
What’s saltation (form of transportation)
Sand particles bounce a long the bed in a leap frog formation
What transportation requires the most energy
Traction
