Hydrosphere - Landforms

Question 1

waterfall

Answer 1

1. hydraulic action = compression of air in river bank causing materials to be dislodged
2. abrasion = force of water throwing bedload against rocks
3. differential erosion where bands of more resistance, harder rock overlay less resistance, softer rock
4. softer rock is eroded easier
5. undercutting causing overhang of hard rock
6. unsupported hard rock collapses to plunge pool over time
7. waterfall retreats upwards

Question 2

oxbow lake

Answer 2

1. meanders = large bends in middle course, w/ river cliffs on the outside bend & slip off slopes formed via erosion & deposition
2. bend becomes more pronounced & neck narrows, bc lateral erosion
3. lateral erosion = hydraulic action (define), abrasion (define)
4. first flood bc rapid rainfall/snowmelt = water bursts banks of river = more direct route, cutting straight thru neck
5. more floods = direct route more established bc more efficient = loop sealed of bc depostition at neck = oxbow lake
6. oxbow lake can dry up unless theres high rainfall

Question 3

meander

Answer 3

1. meander = large bend in middle course
2. smaller river load bc abrasion (define) & attrition (define)
3. water flows faster on outside bend = load will erode outside bend via abrasion = river bank undercut & collapses leaving river cliff
4. river moves slowly on inside bend = larger pebbles deposited = slip-off slope
5. helicoidal flow = corkscrew movement of deposition and erosion
6. differential erosion = bands of hard & soft rock on river bed = pools and riffles = deeper and shallower areas

Question 4

v-shaped valley

Answer 4

1. sources in mountains = quick downhill flow = fast vertical erosion
2. vertical erosion = hydraulic action (define), abrasion (define)
3. as river erodes down, valley sides exposed to freeze-thaw weathering = loosens rocks = steepends valley sides
4. rocks that fell into river mean more abrasion
5. rocks transported down stream via river = wider & deeper channel