1. Sedimentary Rocks

2. Origin:  Comprise 75% of the Earth’s surface  Formed when sediments become compacted and cemented together  Usually has layers called strata The highest layer has the least pressure. The lowest layer has the most pressure.

3. Compaction  What does compaction mean? –Layer upon layer of sediment builds up and the pressure from the upper layers pushes down on the lower layers. –Only SMALL sediments will stick together to form rock

4. Cementation  What does it mean? –Water soaks through soil and rock. The water dissolves minerals in soil and rock. The solution of minerals and water moves between the sediments. The sediments stick together when the minerals crystallize. –Common with LARGE sediments

5. Classification  Sedimentary rocks are classified in 3 ways… 1.Clastic Sedimentary Rocks 2.Chemical Sedimentary Rocks 3.Organic Sedimentary Rocks

6. Clastic Sedimentary Rock  Made from broken fragments of other rocks. –Conglomerate = large/round fragments –Breccia = large/sharp fragments BrecciaConglomerate

7. Chemical Sedimentary Rock  Formed from minerals crystallizing out of a solution Halite (Rock Salt)

8. Organic Sedimentary Rock  Rocks formed from once-living (organic!) things. Organic Limestone