Sedimentary Rocks

1. Sedimentary Rocks Unit 2, Section 1: Minerals, Rocks & Fossils

2. Sedimentary Rocks • Sedimentary Rocks – Form by the compression and cementation of sediment particles • Sediments – small, solid pieces of material that comes from rocks or living things

3. How to form a Sedimentary Rock • Water or wind deposits sediments • The heavy sediments press down on the layers beneath • Dissolved minerals flow between the particles and cement together Sedimentary Rocks

4. Erosion • Erosion – occurs when running water or wind loosen and carry away the fragments of rocks • Destructive forces consistently break up and wear away all rocks on Earth’s surface • Destructive forces – heat, cold, rain, water, and grinding ice Sedimentary Rocks

5. Deposition • Deposition – process by which sediment settles out of the water or wind carrying it • After sediment has been deposited, the process of compaction and cementation change the sediments into sedimentary rocks Sedimentary Rocks

6. Cementation Compaction • Compaction – the process by which sediments are pressed together • Layer upon layer will build up and compact • Cementation – the process by which sediments are glued together Sedimentary Rocks

7. Major Groups of Sedimentary Rocks Rock is classified by the type of sediments that make it up: • ClasticRocks • Organic Rocks • Crystalline Rocks Sedimentary Rocks

8. Clastic Rocks • Clastic rocks – Sedimentary rocks that form when rock fragments are squeezed together • Sediments range in size from clay to boulders • The rocks are grouped by size of rock fragments/particles Sedimentary Rocks

9. Clastic Rocks - Grain Size Large Grains Breccia Small Grains Shale

10. Organic Rocks • Organic Rocks – forms where the remains of plants and animals are deposited in thick layers • Organic – substances that once were part of living things or were made by living things • Examples: • Coal – forms from swamp plants buried in water • Limestone – hard shells of living things like coral, clams, and oysters, produce some kinds of limestone Sedimentary Rocks

11. Organic Bituminous Coal Limestone

12. Crystalline Rocks • Crystalline Rocks – form when minerals that dissolved in a solution crystallize • Ex: Rock salt is made when crystals from chemical precipitates and evaporates • Precipitate – formation of a solid in a solution • Evaporation – process by which water changes from a liquid to a gas/vapor Sedimentary Rocks

13. Crystalline Clastic Conglomerate Rock Salt

14. Fossils • Fossil – the preserved remains of traces of living things • Provide evidence of how life has changed over time • Fossils help scientists infer how Earth’s surface has changed • Fossils normally ONLYform in sedimentary rocks • Palentologists – scientists who study fossils Sedimentary Rocks

15. Steps to create a fossil • An animal/plant dies and sinks into shallow water • Sediment covers the animal/plant • Sediment becomes rock, preserving parts of the animal/plant • Mountain building, weathering, and erosion eventually expose the fossils at surface. Sedimentary Rocks