RocksGroup4

=  = =Sedimentary Rocks=

=
Sediments are small pieces of rock that are moved and deposited by water, wind, glaciers, and gravity. When sediments become glued together, they form sedimentary rocks. The formation of sedimentary rocks begins when weathering and erosion produce sediments. Sedimentary rocks form by weathering and erosion. The weathering and erosion break off sediments from different rocks to form sedimentary rocks. ======  **__Weathering:__ **  Weathering produces sediments. The sediments range in size from huge boulders to microscopic particles. Chemical weathering occurs when the minerals in a rock are dissolved or otherwise chemically changed. While the less-stable minerals are chemically broken down, the more-resistant grains are broken off of the rock as smaller grains. ** __Erosion:__ **Erosion is the removal and transport of sediment. Wind, moving water, gravity, and glaciers transport the sediments. After the rock fragments and sediments have been weathered out of the rock, they are usually transported to new locations through the process of erosion.


 * __Desposition:__**


 * Classification || Texture/grain size || Composition || Rock Name ||
 * Clastic || coarse(>2mm)

medium(1/16mm to 2mm)

fine(1/256 mm-1/16 mm)

very fine(<1/256 mm) || fragments of any rock type -- quartz, chert, and quartzite common quartz and rock fragments quartz, potassium feldspar and rock fragments quartz and clay quartz and clay || conglomerate breccia

sandstone arkose

siltstone shale ||
 * Biochemical || microcrystalline with conchoidal fracture

abundant fossils in micrite matrix oolites (small spheres of calcium carbonate) shells and shell fragments loosely cemented microscopic shells and clay

variously sized fragments || calcite (CaCO 3) calcite (CaCO 3 )

calcite (CaCO 3 )

calcite (CaCO 3 calcite (CaCO  3 )            highly altered plant remains, some plant fossils   || micrite

fossiliferous limestone oolitic limestone

coquina

chalk

coal ||
 * Chemical || fine to coarsely crystalline

fine to coarsely crystalline

very finely crystalline

fine to coarsely crystalline

fine to coarsely crystalline || calcite (CaCO<span style="font-family: Arial,helvetica,sans-serif; font-size: 9px;">3 )

dolomite (Ca,Mg)CO<span style="font-family: Arial,helvetica,sans-serif; font-size: 9px;">3 (will effervesce if powered)

quarts(SiO<span style="font-family: Arial,helvetica,sans-serif; font-size: 9px;">2 ) light colored dark colored gypsum (CaSO<span style="font-family: Arial,helvetica,sans-serif; font-size: 9px;">4 x 2H<span style="font-family: Arial,helvetica,sans-serif; font-size: 9px;">2 O) halite (NaCI) || crystalline limestone dolostone

chert flint rock gypsum rock salt ||