the process by which a river wears away at the land.
the ability for a river to erode depends on its velocity
lateral erosion
starts to occur in the middle course and
prominent in the lower course
vertical erosion
occurs in the upper course
types of erosion:
hydraulic action
sorry this is at the coast but it's the same principal
the force of a river against the banks can cause air to be trapped in
cracks and crevices. the pressure weakens the banks and gradually
wears it away
attrition
stones that have just entered the river are large and jagged. As transportation occurs the stones
collide with each other and knock off each others jagged sides making them smaller and more
spherical. The further they travel the more this occurs.
abraision
sometimes called corrasion
small load scratch and scrape their way down a river during transport, this
wears down the banks and bed of the river channel
solution
also called corrosion
the dissolving of rocks such as limestone or chalk
this could be the load itself
transportation
the process by which a river carries its load.
load is anything carried by a river
all shapes and sizes
all different materials
rocks fallen ito the river or the river banks
and bed that have been eroded
types of transportation:
traction
large or heavy load is rolled along the river bed
not
necessarily
heavy load, it
could be that
the rivers
velocity is not
big enough
load carried in this way is called bedload
saltation
Small pebbles and stones are bounced along the river bed.
When velocity increases they are picked up, when it
decreases they are deposited.
suspension
fine light material such as alluvium is held up and
carried within the rivers flow
this is called suspended load
solution
Annotations:
yes, again
minerals are dissolved in the water
this is a chemical change to rocks
such as limestone and chalk
load carried in this way is called solute load
deposition
the bigger the load particle the more velocity is needed to keep it moving.
when velocity falls, big boulders are therefore the first to be deposited
this explains why mountain streams have boulders along their bed while there is only fine silt near the mouth
the river will deposit more load when there is a period of
draught and the discharge is low