Rocks are made in different ways. One rock type is called sedimentary, which is a form of rock made by the deposition and compression of small particles. Sediment is made of soil particles. The deposition of sediment means that it has been transported from one place to another and over time builds up, layer by layer. Compaction is the process by which the particles are pressed together.
While disposing waste paper, you can demonstrate deposition and compaction.
Demonstrate Deposition using these steps:
Loosely wad separate pieces of waste paper, such as newspaper or discarded craft paper.
Place the wadded paper in a container, such as a trash can or even a box.
| Measure or mark the height of the wadded paper in its container.
Use your foot to press the paper wads down in the container.
Results: The height of the paper initially is greater than the height after pressing it with your foot.
Placing the paper wads in the waste can represents deposition, which is the buildup of sediments. Stepping on the paper wads represents compaction ( process of particles being pressed together). Your weight presses the pieces of paper together so that they take up less volume. This happens to sediments in water. Newly deposited sediments, like the wads of paper, have spaces between them. Water fills these spaces. But when more sediments are deposited, the weight of the new layers presses on underlying layers of sediments. This causes the water to be squeezed out and the particles pack tightly together.
For more information about the formation of rocks, see Janice VanCleave’s Rocks and Minerals.