Sam: Different types of sedimentary rock get deposited in different places. The location depends on how fast the water is moving and how heavy the sediments are.

Animation. A cross-section of a coastal environment. Rivers run down hill and into the ocean. Sedimentary deposits of different types are outlined.

Sam: In a coastal setting, river sediments are deposited above the shoreline. As you move further from shore the water's movement is slower. Heavier sediments are deposited closer to the shore, while lighter sediments are carried further out.

The sea level starts to decrease and the positions of the deposits move outward with it. Previous deposits remain where they were.

Sam: Over time, as sea levels rise and fall, where these sediments are deposited shifts. This causes different rock types to stack on top of each other. This is called interfingering.

The sea level starts to rise and the positions of the deposits move inward with it. Previous deposits remain where they were.

Sam: This also explains why at Dinosaur Peak there are terrestrial rocks on top of marine rocks.