The camera slowly pans across a landscape. A river runs through a forest. The leaves are changing on the trees making the canopy appear yellow.

Sam: New rocks are being made right now! Through the processes of deposition and lithification, new layers are always being added to the geological record. What kinds of sediment are being deposited here? Faster rivers can transport more sediment so they only leave behind deposits of larger rocks. Slower moving rivers might leave behind deposits of finer sand. This river is somewhere in between, so it leaves behind deposits of mixed gravel and sand. The wide, flat areas to either side of the river are called floodplains. This area only sees deposition when it rains so much that the river overflows. As the water level slowly settles, a deposit of fine silt will cover the floodplain.