Sedimentary Rocks Notes

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

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. Rocks that appear to be made of pieces smashed or layered together. • Small Sediments – Typically clay, silt and sand.

• 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. ROCKS That appear glued together.

• Large Sediments – Typically silt, sand and gravel.

•Look at Diagram B on page 102

Weathering and Erosion make and move sedimentsWeathering – process that breaks rocks into

smaller piecesErosion –movement of weathered materials

3 classification types of Sedimentary Rocks

This is what they are made of…Clastic – made of fragments of rock

cemented or compacted togetherBreccia is a term most often used for clastic sedimetary 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.

Sandstone is also clastic even though it’s hard to see different sediments.

3 classifications of Sedimentary Rocks

Chemical – minerals crystallize out of solution to become rock

Limestone is a sedimentary rock composed primarily of calcium carbonate (CaCO3) in the form of the mineral calcite. It most commonly forms in clear, warm, shallow marine waters.

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3 classifications of Sedimentary Rocks

Organic – 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.