sentence: Layers are made by deposition of sediment, organic matter, and chemical precipitates.
sentences_before: Sedimentary rocks are the most common rocks on Earth. They form at or near the Earth's surface. Sedimentary rock is formed in layers which were laid down one by one on top of another. Some of the layers are thin, some are thick.
sentences_after: Deposition is followed by squeezing of sediment under its own weight, and cementation.
concept_name: layer
headings: Rock (geology) Rock classification Sedimentary rock