Formation of Sedimentary Rocks Compaction of sediments –Weight of overlying sediments “squishes” the fragments together. Cementation of sediments –By quartz or calcite
3 Types of Sedimentary Rocks #1 CLASTIC #2 CHEMICAL #3 ORGANIC
CLASTIC Sedimentary Rocks Classified by the size of the sediments within the rock Rounded pebbles – –Conglomerate Angular gravel – –Breccia Visible pieces of sand – –Sandstone Clay/mud particles – – Shale
CHEMICAL Sedimentary Rocks Formed from minerals that were dissolved in water Precipitation Calcite, Chemical Limestone Evaporation Gypsum, halite 5/6 & 7/8 start here
Organic Sedimentary Rocks Formed by once-living organisms Examples: –Coquina Large sea shells –Chalk Microscopic Sea shells –Coal dead plants in swamps –Organic limestone Fossils Coral
Sedimentary Rock Structures Stratification Ripple Marks Mud Cracks Fossils Concretions 3 rd period start here on Monday
Assignments Work in small groups to separate your “Box of Rocks” into 3 groups: 1- Clastic = Pieces 2- Chemical = minerals from water 3- Organic = fossils, coral, seashells, coal Can you name each rock? Wash your hands/table & leave box of rocks on your table. Begin working on Chapter 6 interactive note sheets.