Sedimentary Rocks

DID YOU KNOW? 75% of rocks exposed at Earths surface are sedimentary Sedimentary rocks form in various regions oceans, lakes, rivers, beaches glaciated areas deserts

Sedimentary Rock Sedimentary – Formed in layers as a result of pressure on sediments (small pieces of rock) Sediments settle in low places, usually near or under bodies of water. No Heat involved in formation

Sedimentary Rocks Over time the sediments form layers that are compacted together over time and form rocks. Sedimentary rocks are almost always found in layers Strata Stratification – the process in which sedimentary rocks are arranged in layers

Form By Three Main Processes Compaction- Sediments get compressed and compacted. Cementation-Small crystals precipitate and act as glue that holds the rock together. Precipitation-Crystals precipitate directly from solution. Sedimentary Rocks

There are 3 Types… Clastic – formed from weathering debris Chemical – form when dissolved materials precipitate from solution Organic – form from the accumulation of plant or animal debris

Clastic Breccia Conglomerate Contains large angular fragments Large rounded fragments Sandstone Shale Sand-sized debris, often found around beaches and deserts Made of clay-sized debris, often breaks into flat pieces

Chemical Limestone – forms chemically from precipitation of calcium carbonate from lake or ocean water Rock salt – forms from the evaporation of ocean or saline lake waters. Rarely found at Earth’s surface

Organic Coal – Forms from Plant Debris – Often found in Swamp areas