Sedimentary Rocks Vocabulary Sedimentary Rock when sediments become pressed or cemented together or when sediments precipitate out of a solution. Sediments loose materials such as rock fragments, mineral grains, and bits of plant and animal remains that have been moved by wind, water, ice, or gravity Weathering process that breaks rocks into smaller pieces Erosion movement of weathered materials 2 ways Sedimentary Rocks form Compaction When layer upon layer of sediment builds up. Pressure from upper layers pushes down on the lower layers. If sediments are small enough they stick together and form solid rock. Small Sediments Look at Diagram A on page 102 2 ways Sedimentary Rocks form Cementation When water soaks through soil and rock. As it moves, it dissolves minerals in the rock such as calcite, hematite, and limonite. The solution of water and dissolved minerals moves through open sediments and glues those sediments together. Large Sediments Look at Diagram B on page 102 3 classifications of Sedimentary Rocks Clastic made of fragments of rock cemented or compacted together Breccia is a term most often used for clastic sedimentary rocks that are composed of large angular fragments (over two millimeters in diameter). The spaces between the large angular fragments can be filled with a matrix of smaller particles or a mineral cement that binds the rock together. Breccia is a term most often used for clastic sedimentary rocks that are composed of large angular fragments (over two millimeters in diameter). The spaces between the large angular fragments can be filled with a matrix of smaller particles or a mineral cement that binds the rock together. 3 classifications of Sedimentary Rocks Chemical sedimentary minerals crystallize out of solution to become rock Limestone is a sedimentary rock composed primarily of calcium carbonate (CaCO 3 ) in the form of the mineral calcite. It most commonly forms in clear, warm, shallow marine waters.. Limestone is a sedimentary rock composed primarily of calcium carbonate (CaCO 3 ) in the form of the mineral calcite. It most commonly forms in clear, warm, shallow marine waters.. 3 classifications of Sedimentary Rocks Organic sedimentary remains of plants and animals Coal is an organic sedimentary rock that forms from the accumulation and preservation of plant materials, usually in a swamp environment. Coal is a combustible rock and along with oil and natural gas it is one of the three most important fossil fuels. Coal is an organic sedimentary rock that forms from the accumulation and preservation of plant materials, usually in a swamp environment. Coal is a combustible rock and along with oil and natural gas it is one of the three most important fossil fuels.