1. Topic 6 – Running Water

2. How does running water weather rock?
Lifting – fast-moving water pushes into cracks, lifting off rock pieces
Abrasion – Sand, pebbles and rocks carried by the water scrape against other rock
Dissolving – Some minerals in rock are dissolved as the water runs over them

3. 2. Erosion from running water
Produces rounded rocks (“spheroidal” weathering)

4. Happens where running water moves FAST:
River channel gets narrower
Rapids
Waterfalls
Outside corners of streams/rivers
Steep mountain slopes
** Note: Fast water tends to move in a straight
line

5. Occurs at the bottom (underwater base) of the stream/river
Called downward erosion
Water cuts the earth downwards
Causes a V-shaped valley

6. Occurs at the head of the stream/river (where it begins up the mountain)
Called headward erosion
Happens because water pools at the head of a stream
Causes the stream to cut itself higher up the mountain

7. Occurs when running water rounds a bend
Erosion occurs on the outside edge of the bend
The outside of the bend is where the water is running faster

8. Can undermine waterfalls
Undermining = when rock at the base of a waterfall is eroded, causing the rock above to become unstable and fall
Causes a waterfall to recede (move backwards)

9. Deposition happens when running water moves SLOW:
3. Deposition from running water
Deposition happens when running water moves SLOW:
River channel gets wider
River enters lake/pond/ocean
Inside corners of streams/rivers
River valleys
Floods
** Note: Slow water tends to meander/curve

10. Occurs where the river ends (at the ocean)
Deposits called a delta
Occurs when running water rounds a bend
Deposition occurs on the inside edge of the bend
The inside of the bend is where the water is running slower

11. Deposits are sorted
Heavy materials are deposited first (first gravel, then sand, then silt, then clay)

12. 4. Running Water in Mountains vs. Valleys
Water is a stream (it gets bigger the further down it flows)
Water travels over steep slopes
Water flows fast and straight

13. In valleys:
Water is a river (has gotten big)
Water travels over flat land
Water meanders and travels more slowly

14. Erosion and deposition in a meandering river:
End result: The meander gets wider!