Sedimentary rocks cover the majority of the Earth's exposed continents (73% of the Earth's current land surface). These rocks are formed by deposition and subsequent cementation of material, either at the Earth's surface or in oceans, lakes and rivers. This material, or sediment, is derived from the products of weathering and erosion, transported and then deposited by water, wind or ice. Sedimentation may also take place on the sea-floor as aquatic creatures settle out of suspension or minerals are precipitated.
The study of sedimentary rocks is important for understanding a wide range of subjects related to the Earth's history, including palaeontology, palaeogeography and palaeoclimatology. Understanding sedimentary rocks is also important for civil engineering, natural resource extraction and water management.
Explore the virtual outcrops below. They represent rocks that have been deposited in a variety of environments and settings, and cover a wide range of geological ages.