erosion landforms Flashcards
what is a v-shaped valley?
a narrow, steep-sided valley formed as a result of vertical erosion by a stream or river.
v-shaped valleys
•a river, transports material along its bed, known as its load.
•the material cuts downwards known as vertical erosion which creates a v-shaped valley.
where are v-shaped valleys found?
in the upper course.
how are v-shaped valleys created?
- a river transports its load.
- erosive processes occur, mainly abrasion, vertical erosion takes place creating steep sided banks.
- the banks are left unsupported.
- the banks collapse, a v-shape is left behind, known as a v-shaped valley.
what are interlocking spurs?
ridges of high ground that project into v-shaped valleys. they occur on alternative sides of a valley and interlink.
in the upper course the river does not have enough power to what?
erode laterally.
how are interlocking spurs formed?
interlocking spurs are found in the upper course of river transport its load, and due to erosion, mainly abrasion, vertical erosion of the river bed will take place. this will form steep banks, which lack support, so collapse. this leaves behind a v-shaped valleys. the interlocking spurs form as rivers do not have the power to erode laterally in the upper course. as a result, they must wind round the high hillsides that stick out in their path. the hillsides interlock creating the interlocking spurs.
what are the 3 sections rivers long profile?
•upper course- landforms of erosion
•middle course- landforms of erosion and deposition
•lower course- landforms of deposition
what is a waterfall?
a sudden fall of water over a steep drop.
how is a waterfall formed?
a waterfall occurs as water drops from a height when a river or stream flows over a steep drop.
1. waterfalls form in the upper course, where the river flows over hard and soft rock.
2. soft rock erodes quicker than the hard rock, often by hydraulic action, creating a plunge pool which undercuts the hard rock. the hard rock now overhangs.
3. as the overhang is left unsupported, it collapses. the rocks fall into the plunge pool, and act to erode the plunge pool further by abrasion.
4. overtime, the sequence of processes repeats, and more erosion and undercutting causes further collapse. the waterfall retreats upstream, leaving a steep-sided gorge.
what is an undercut?
cut or wear away the part below a rock, leaving it unsupported.
what is a gorge?
a steep sided valley left behind when a waterfall retreats upstream.
how is a gorge formed?
a gorge is left after the waterfall retreats upstream. it can take thousands of years to form.
