Sedimentary rocks form at the surface of the Earth, and during that process, they record information about conditions during their formation. For example, a poorly sorted conglomerate will indicate the presence of a rapidly moving stream while a breccia will indicate rock types nearby its depositional site and may also indicate instabilities like earthquakes or landslides because of its rapid deposition. The cements indicate the types of fluids traveling through the rocks, and fossils give information about the environment of deposition.