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6.1/6.2 Guided Notes Hybrid

6.1/6.2 Guided Notes Hybrid. Weathering and Erosion. Sediments: small pieces of rock that are moved and deposited by water, wind and gravity. Lithification:. Sediment is deposited in low areas such as valleys and ocean basins Bottom layers are subjected to intense pressure and temperatures

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6.1/6.2 Guided Notes Hybrid

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  1. 6.1/6.2 Guided Notes Hybrid

  2. Weathering and Erosion • Sediments: small pieces of rock that are moved and deposited by water, wind and gravity

  3. Lithification: • Sediment is deposited in low areas such as valleys and ocean basins • Bottom layers are subjected to intense pressure and temperatures • This process is called lithification: THE PHYSICAL AND CHEMICAL PROCESSES THAT TRANSFORM SEDIMENT INTO SEDIMENTARY ROCK

  4. Erosion: removal and transport of sediment Agents of erosion: • Wind • Moving water • Gravity • Glaciers

  5. Sedimentary Features: • Sedimentary rock tells geologists the history of the area • BEDDING: predominant feature of sedimentary rock is the horizontal layering • Feature results from the way water or wind causes the sediment to settle out • Two types of bedding

  6. Bedding Type #1: Graded Bedding • Bedding in which heavier and coarser particles are located near the bottom of the sedimentary rock

  7. Bedding Type #2: Cross-Bedding • Inclined layers of sediment deposited along a horizontal surface

  8. Mud Cracks and Ripple Marks • Mud (usually forms in hexagonal plates) cracks and sediments seep between the mud plates • The sediments build up over time forming sedimentary rock • Ripple Marks: • Evidence that the sediment was formerly moved by wave action

  9. Fossils • The best known feature of sedimentary rock is the propensity to find fossils in it • During lithification the animal’s parts (like the shell) can be replaced by minerals and turned to rock which make up a fossil

  10. Types of Sedimentary Rock • Clastic / Detrital – made up of solid particles (gravel, sand, silt and clay) derived from preexisting rocks through weathering • Chemical – sedimentary rocks that result from inorganic chemical processes or from the chemical activities of organisms

  11. Clastic / Detrital Sedimentary Rocks • Coarse-grained • Gravel sized fragments • Types of rock formed: conglomerate (rounded gravel), breccia (angular gravel) • Formed by high-energy flows of water • Medium-grained • Sand fragments • Type of rock formed: sandstone • Formed by stream & river channels, beaches, deserts • Importance: due to pore spacing, fluids can move through and thus hold reservoirs of oil, natural gas, and groundwater • Fine-grained • Silt and mud fragments • Type of rock formed: siltstone, shale, mudstone • Importance: low porosity resulting in a barrier to movement of groundwater & oil.

  12. Chemical Sedimentary Rock • Inorganic Sedimentary Rock • Evaporite – form as a result of crystal grains precipitating our of a supersaturated body of water • Type of rock formed: rock gypsum (made up of the mineral gypsum) & rock salt (made up of the mineral halite)

  13. Chemical Sedimentary Rock • Biochemical – form as a result of the chemical processes of organisms, many times the remains of once-living plants and/or animals. • Types of rock formed: limestone, chert, and coal. • Form in shallow-water, swamp, and coastal environments chert coal

  14. Importance of Sedimentary Rock • Provide historical timeline for area. Leaves a ‘footprint’ of all that’s come before us. • Past plants and animals • Bedrock • Ancient rivers, lakes and shorelines • Provides resources • Oil, natural gas, and coal • Building materials • Uranium • Phosphate and iron

  15. Deposition • Occurs when transported sediments are deposited on the ground or sink to the bottom of a body of water • Settles with the largest grains at the bottom of the layering and the smallest grains at the top

  16. Lithification part 1 COMPACTION • The weight forces the sediment grains to get closer and closer together causing physical changes to occur • Mud can contain up to 60% water that gets squeezed out • Sand does not compact as much as mud does because sand is mostly quartz • Grain to grain contact in sand forms a supporting framework that maintains open space between the grains

  17. Lithification part 2 CEMENTATION • Minerals like calcite CaCO3 and iron oxide Fe2O3 flow through the open spaces left by compaction • The minerals linger and cement the grains together forming sedimentary rock

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