Rivers Flashcards
what is the river like in the upper course?
steep v-shaped steep sides narrow shallow channel
what is the river like in the middle course?
medium gradient
gently sloping sides
wider
depper channel
what is the river like in the lower course?
low gradient very wide almost flat very wide deep channel
what are the 5 processes of erosion in a river?
- vertical and lateral erosion
- hydraulic action
- abrasion
- attrition
- solution
what does vertical erosion do the river?
- deepens river channel, V-shaped
- upper course
what does lateral erosion do to the river?
- widens Vally
- middle and lower course
what is hydraulic action?
force of water breaks down rocks away from river channel
what is abrasion?
- eroded rock scrape channel
- most erosion is abrasion
what is attrition?
- eroded rock smash into each other
- edges round off
what is solution?
-river water dissolves certain types of rock i.e. limestone
what is transportation?
movement of eroded material
what are the 4 main methods of transportation?
- traction
- saltation
- suspension
- solution
what is traction?
large particles push along river bed by water
what is saltation?
pebble sized bounce along river bed by water
what is suspension?
small particles like soil and clay carried in water
what is solution?
soluble material dissolved in water carried along
what are the 4 reasons a river deposits material?
- volume of water in river falls
- eroded material increases
- sallow water
- river reaches mouth
what are the 3 land formed formed from erosion?
- waterfalls and gorges
- interlocking spurs
how are waterfalls and gorges formed?
- river flows over hard rock which is over soft rock
- soft rock eroded by hydraulic action and abrasion
- step formed
- water flows over step erodes more soft rock
- steep drop formed, WATERFALL
- hard rock undercut, collapse
- rock erodes at base by abrasion
- more undercutting, collapse
- waterfall retreats, GORGE
how are interlocking spurs formed?
- upper course river erode vertically
- v-shaped valleys
- not powerful enough to erode laterally
- wind around high hillsides
- leaving interlocking spurs