Streams erode their channels by abrasion, by dissolving soluble material, and by layering polishing grinding evaporation

grinding

Explanation:

The streams are very powerful agents when it comes to erosion. With their power and chemical composition, the streams manage to erode the rocks easily and even the hardest rocks experience significant changes or are totally destroyed over time. The water of the streams manages to break down the rocks into small or big pieces, and as it does it moves them away. The rocks that are carried are constantly colliding with other rocks along the way, causing even more pieces to break and to be eroded, thus the grinding type of stream erosion.

The correct answer is grinding.  

Explanation:

The ability of a water stream to erode and transport materials that it has collected from the ground during the water cycle depends largely on the speed with which it moves. A current channel is the direction in which water moves in a current.

These currents perform erosion by lifting loose particles by abrasion, and grinding and dissolving the soluble material they collect. The faster the water moves and produces greater turbulence, it will produce greater erosion.

The three ways to transport sediments during this cycle are: in solution, in suspension and sliding or rolling along the bottom.

the answer to your question is slate