The upper course of a river is usually the …………………………… flowing as they pass through ………………….. land. Since the river is flowing so fast, there is a great deal of …………………….. due to the ……………………. So ……………………….. is the river at the upper reaches that it is almost able to cut path in a straight line and carrying away large ………………………. and boulders as well as ……………………….. and stones.
FILL IN THE BLANKS USING THESE WORDS energy rocks powerful steep fastest gravel velocity |
Transport
Water, wind, and gravity are the main processes that move pieces of rock from place to place. Sediment might get transported thousands of miles by one of the world's major rivers, or it might just go from the top of the hill to the bottom during a landslide or as a result of natural "creep". During this journey, a lot can happen to the sediment. For example, it can continue to erode into smaller pieces during transport. This happens because a piece of rock bumps into other rocks during transport and breaks into smaller pieces (erosion!). So transport can also include some erosion, and the longer it takes to transport a rock, the more chance it has to erode. |
Deposition
Once the sediment stops being transported, you have a bunch of pieces of sediment in one place. A pile of sand is an example; you might find such a pile at a sandbar along the edge of a river. You can also find sediment that has been deposited at the bottom of steep hills, at the beach, in sand dunes, and many other places on earth. Larger pieces are harder to transport, so they tend to stop moving (deposition) before smaller pieces. For example, a huge boulder cannot move in a tiny trickle of water, but can move during a raging flood. Similarly, a muddy river flowing into the ocean dumps most of the larger pieces of sediment near the coast in what we call a "delta," but the really tiny pieces stay suspended in the water and can travel far out into the open ocean before finally settling to the bottom. |