Flashcards
River long and cross profiles: erosion processes by course
Flashcards do conjunto (5)
- 1What is the long profile and cross profile of a river and how do they vary on the river's course?1) The path of a river as it flows downhill is called its course.
2) Rivers have an upper course (closest to the source of the river) and a middle course and a lower course (closest to the mouth of the river).
3) Rivers from channels and valleys as they flow downhill.
4) They erode the landscape - wear it down, then transport the material to somewhere else where it's deposited.
5) The shape of the valley and channel changes along the river depending on whether erosion or deposition is having the most impact (is the dominant process).
6) The long profile of a river shows how the gradient (steepness) changes over the different courses.
7) The cross profile shows you what a cross-section of the river looks like. - 2Explain what happens at each stage of the course.1) Upper course, steep gradient, V-shaped valley, steep sides. Narrow, shallow channel.
2) Middle of the course, medium gradient, gently sloping valley sides. Wider, deeper channel.
3) Lower course, gentle gradient, very wide, almost flat valley. Very wide, deep channel. - 3What is vertical erosion?Vertical erosion: This deepens the river valley (and channel), making it V-shaped. It's dominant in the upper course of the river.
- 4What is lateral erosion?Lateral erosion: This widens the river valley (and channel). It's dominant in the middle and lower courses.
- 5Name and describe the four processes of erosion.1) Hydraulic action : The force of the water breaks rock particles away from the river channel.
2) Abrasion : Eroded rocked picked up by the river scrape and rub against the channel, wearing it away. Most erosion happens by abrasion.
3) Attrition : Eroded rocks picked up by the river smash into each other and break into smaller fragments. Their edges also get rounded off as they rub together.
4) Solution : River water dissolves some types of rock e.g. chalk and limestone.
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