Sediment: means small pieces of rock
Formed by weathering, erosion and deposition.
o Weathering: the breaking down of rocks and other materials on Earth’s surface
(caused wind and water)
o Erosion: The moving of materials caused by weathering
o Deposition: The process where sediments that were carried by erosion are put in a new location. (Usually involves compacting and cementing of many materials together)
Sedimentary rocks are classified by the composition of the materials in them.
There are three main categories:
Clastic Rocks: made from fragments of existing rocks and the size and shape of those pieces. They are cemented together with clay, mud or sand.
Sandstone: made from sand-sized pieces
Shale: dust sized fragments (with mud or clay)
(If over of the rock is made of pebbles, the rock is a conglomerate. Puddingstone is an example of a conglomerate.
Organic Rocks: made from organisms that were once living.
Organic means living
Many were formed from shells of crustaceans and microorganisms.
Limestone, and coral reefs are examples
Chalk is a type of fine-grained limestone.
Coal is another example
Chemical Rocks: formed when seas dried up, leaving minerals dissolve in the water.
Some Limestone forms this way.
Rock salt and Gypsum are other examples.