2. Aim: How can we explain sedimentary rock formation?

3. Sedimentary Rocks  Formed from sediments Sediments (clasts): solid pieces of rock that have been eroded or weathered from old rocks  Erosion and weathering caused by water, wind, gravity, and glaciers.

4. Methods of Formation

5. 1. Cementation  Sediments cemented together by dissolved minerals  Form a clastic sedimentary rock  Sandstone, conglomerates

8. 2. Compaction  Sediments compressed together by weight of overlying water or rock  Shale and coal formed only by compaction

10. 3. Chemical Action  Dissolved minerals drop out of water (precipitate) - caused by evaporation, saturation of minerals, or changes in temp  Intergrown mineral crystals form chemical sedimentary rock

12. Rock salt Rock gypsum Dolostone Chemical sedimentary rocks have no sediments, but are intergrown minerals of one variety

13. 4. Organic Processes  Any rock made by living organisms or mostly composed of materials from life forms is called a bioclastic sedimentary rock  Ex: limestone of a coral reef

14. Limestone (fossiliferous)Limestone (chalk) Bioclastic Sedimentary Rocks Coal

15. Characteristics of Sedimentary Rocks  Most are clastic – composed of fragments  Fragments usually rounded by weathering  Usually sorted into sizes Conglomerate Breccia

17. Characteristics continued…  Usually contain layers or strata  Some show cracks, rain drop impressions, or ripple marks  Some contain fossils

18. SEDIMENTARY ROCKS are…

19. Layers or Strata

20. Ripple marks

21. Mud Cracks

22. Fossils

23. State Fossil of New York

25. Conglomerate (clastic, large rounded particles)

26. Breccia (clastic, large angular particles)

27. Sandstone (clastic, sand sized particles)

28. Siltstone (clastic, smaller particles)

29. Shale (clastic, even smaller particles)

30. Rock Salt (chemically formed)

31. Rock Gypsum (chemically formed)

32. Dolostone (chemically formed)

33. Limestone (Biologic origin)

34. COAL (organically formed)

35. REGENTS QUESTIONS Which sedimentary rocks are formed mostly of organic matter? (1) Rock salt and shale (2) Coal and limestone (3) Dolostone and rock gypsum (4) Sandstone and conglomerate

36. The following diagram represents the formation of a sedimentary rock. Sediments Sedimentary Rock Which two processes formed this rock? (1)folding and faulting (2)melting and solidification (3)compaction and cementation (4)heating and application of pressure