Question

1. a river flowing through soft rock dissolves some of the rock and carries this material downstream. what is this an example of?

physical weathering, then erosion by wind
physical weathering, then erosion by water
chemical weathering, then erosion by water
chemical weathering, then erosion by wind

1. niagara falls is a big waterfall on the border of canada and the united states. each year the edge of the waterfall moves back a couple of centimeters because the water is breaking apart the rocks on the edge. what is this an example of?

chemical weathering
physical weathering, then erosion by wind
physical weathering, then erosion by gravity
physical weathering, then erosion by water and gravity

Explanation:

For Question 6:

Dissolving rock is a chemical change (chemical weathering), and the river (water) carries the dissolved material downstream, which is water erosion.

For Question 7:

Water breaking apart rocks is physical weathering; the broken rock material is moved by water flow and gravity as the waterfall edge retreats, so it is physical weathering followed by erosion by water and gravity.

Answer:

1. Chemical weathering, then erosion by water
2. Physical weathering, then erosion by water and gravity