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Sedimentary rocks

Sedimentary rocks

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Sedimentary rocks

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  1. Sedimentary rocks

  2. Sedimentary rocks • Rocks that form from an accumulation of sediments derived from preexisting rocks and/or organic materials. • These rocks form by various process that occur on or within the top few kilometers of earth’s crust

  3. Most sedimentary rocks are made up of solid fragments or sediments, often called “clasts”, that have been weathered or eroded from older rocks. • Clastic texture rocks are composed of smaller rock fragments called sediments. Classified by their particle size

  4. Pebbles, cobbles and/or boulders some silt sand or clay

  5. Sand Size of particles: from .0006cm to .2cm

  6. Silt particles Particle size: .00004 to .006 cm

  7. Clay Clay magnified 1,600 times Particle size: less then .0004 cm

  8. Cementation • Often the clasts, such as sand, silt, and pebbles, are cemented together in a process called cementation. This happens as the sediments lose water and the dissolved minerals in the pores of the sediments forming a crystalline mineral material

  9. Chemical sedimentary rockCrystalline Texture • When dissolved minerals drop out of water (precipitate), they form a mass of intergrown or interconnected mineral crystals • You can see crystals in the rock. The crystals are composed of only one mineral

  10. Bioclastic • No crystals, No rock particles. May have shell or shell fragments in it, or be completely black in color consisting of dead organic material Limestone Coal