What is Sedimentary rock?
[[File:Limestoneshale7342.jpg|thumb|right|230px|Two types of sedimentary rock: limey [[shale]] overlaid by [[limestone]]. Cumberland Plateau, [[Tennessee]].]] [[File:Red sandstone, Hilbre Island.JPG|thumb|right|230px|Red sandstone: [[Wirral]], [[England]]]] [[File:Sedimentary-rock.jpg|thumb|right|230px|Sedimentary rock: [[Karnataka]], [[India]]]] [[File:Pressure solution sandstone.svg|thumb|[[Pressure solution]] at work in a [[clastic rock]]. While material dissolves at places where grains are in contact, material crystallizes from the solution (as cement) in open pore spaces. This makes a net flow of material from areas under high stress to those under low stress. As a result, the rock becomes more compact and harder. Loose sand can become sandstone in this way.]] [[File:Grube Messel Fossil 2005-09-24.jpg|thumb|right|230px|Fossil in shale: [[Messel Pit|Grube Messel]], [[Germany]]]] '''Sedimentary rocks''' are [[Rock (geology)|rocks]] formed from [[sediment]]. They are deposited over time, and often show layers which can be seen in [[cliff]]s. Other types of rock are [[igneous rock]] and [[metamorphic rock]]. Sediments are usually formed from matter which falls to the bottom of [[ocean]]s and [[lake]]s. The matter includes tiny pieces of other rocks, and dead animals, plants and [[microorganism]]s. Also, [[inorganic chemistry|inorganic]] [[chemical]]s may be [[precipitate]]d from [[solution]] in the water. The three most common sedimentary rocks are [[limestone]], [[sandstone]] and [[shale]].<ref>Blatt H; Middleton G. & Murray R. 1980. ''Origin of sedimentary rocks''. Prentice-Hall. {{ISBN|0-13-642710-3}}</ref> Sedimentary rocks cover 75{{ndash}}80% of the Earth's land area, but they make up only 5% of the [[Earth's crust]]. The relative abundances of the different types of sedimentary rocks are: *[[Shale]] - 60% *[[Sandstone]] - 20% *[[Carbonate]] - 15% *All others - 5% == Consolidation == Squeezed and compressed over time, the sediments become 'consolidated' (made solid) into layers of rock. [[Stratigraphy]