1.3-River landscapes Flashcards
What are 2 physical processes that shape a river?
weathering and mass movement
What are the 3 types of weathering?
mechanical
chemical
biological
What is biological weathering?
Roots growing and animals burrowing into cracks in rocks causing them to split apart.
What is chemical weathering?
slightly acidic rainwater dissolves rocks
What is mechanical weathering?
freeze thaw action
What is the process of freeze thaw action?
water fills a crack
water freezes and the crack widens
repeated action increases the size of the crack
loose blocks if rocks are called scree
What are 2 processes of mass movement?
sliding and slumping
What is sliding?
where rock or material moves down a slope under the influence of gravity
what is slumping?
Where the river erodes the bottom of the valley slope causing the rock to become saturated and slump/collapse, making the slope steeper.
What does slumping cause?
material to slide downwards particularly if it’s saturated with rainwater
What is hydraulic action?
where the force of the water of the bed and banks removes material
What is attrittion?
the load that is carried by the river bumps together and wears down into smoother pieces
what is solution?
some minerals dissolving in river water
What is abrasion?
material carried by the river rubs against the bed and banks
What are the 4 main types or river transportation?
traction
salatation
suspension
soloution
What is it when large boulders are rolled along the river bed?
traction
What is it when smaller pebbles are bounced along the river bed?
salatation
What is it when finer sand and silt particles are carried along in the flow?
suspension
What is it called when some minerals are dissolved in the water and carried along in the flow?
solution
What shows how a river changes from source to mouth?
The Bradshaw model