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Sedimentary Rocks. Sedimentary Rocks. Related word = “sediment” Sediment - pieces of solid material that have been deposited on earth’s surface by water, wind, ice, gravity or chemical precipitation. Sedimentary Rocks. Related word = “sediment”
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Sedimentary Rocks • Related word = “sediment” • Sediment - pieces of solid material that have been deposited on earth’s surface by water, wind, ice, gravity or chemical precipitation
Sedimentary Rocks • Related word = “sediment” • Sediment - pieces of solid material that have been deposited on earth’s surface by water, wind, ice, gravity or chemical precipitation
Weathering • a set of physical and chemical processes that break rock into smaller pieces • Chemical weathering - • When minerals in a rock are dissolved and the rock is changed chemically • Physical weathering - • Minerals remain unchanged • Simply break into small pieces
Clastic Sediments • Produced by weathering
Erosion and Transport • The removal and movement of surface materials from one location to another • Carried by wind, water, ice and gravity • Materials usually move downhill
Deposition • When materials are laid down on the ground or sink to the bottom of bodies of water • When transport stops, materials are deposited • Generally, largest particles settle out first and produce sorted layers • Glacier and landslide deposits not sorted
Burial • When materials are deposited in basins, other sediments are deposited on top if them. • This leads to the layered appearance that some sedimentary rocks exhibit
Lithification • Litho?
Lithification • Litho? • Lithification - the physical and chemical processes that transform sediments into sedimentary rocks Compaction Cementation Lithification
Lithification • Compaction? (Similar words?) • Compaction - clasts (?) are squeezed together. Water is squeezed out.
Lithification • Cementation? (Similar words?) • Cementation - mineral growth in spaces between clasts cements clasts together • Two methods:
Features of Sedimentary Rocks • Bedding - visible horizontal layers in the rock • Beds can be millimeters thick or meters thick • Type of bedding depends upon the method of transport. • Size of grains depend on many factors
Graded Bedding • Particle size is bigger and coarser at the bottom of the beds • Underwater landslides, fast-moving streams
Cross-Bedding • Formed as inclined layers of sediment move forward across a horizontal surface • Sand dunes, beaches, lake edges
Cross-Bedding • Formed as inclined layers of sediment move forward across a horizontal surface • Sand dunes, beaches, lake edges
Evidence of Past Life • Fossils - preserved remains, impressions or any other evidence of once-living organisms (Why not in igneous?)
Fossils and Sedimentary Rocks • Fossilscan help ID the rocks, and vice-versa! • Types of fossils found give a clue about the rock’s origin- fossils of marine animals indicate ……
Fossils and Sedimentary Rocks • Fossilscan help ID the rocks, and vice-versa! • Types of fossils found give a clue about the rock’s origin- fossils of marine animals indicate …… • The rock formed from sediments deposited near (or in) the sea.
Clastic Sedimentary Rocks • Coarse-Grained Clastics Conglomerate Breccia
Clastic Sedimentary Rocks • Grain Shape - Influenced by: • Distance of transport - The further it travels, the rounder it becomes • Length of time of transport- The longer it’s affected by water, wind or ice, the rounder it becomes
Clastic Sedimentary Rocks • Medium-Grained Clastics - (Sandstone) sometimes contain oil, natural gas and groundwater • Porosity: percentage of open space between grains
Clastic Sedimentary Rocks • Fine-grained Clastics (Shale) • Has low porosity that hinders movement of oil, water and natural gas
Chemical Sedimentary Rocks • Formed from the evaporation of saturated liquids • Called evaporites
Organic Sedimentary Rocks • Biogenic - (bio = ?; genic = ?)
Organic Sedimentary Rocks • Biogenic - (bio = ?; genic = ?) • Formed from the remains of once-living things - limestone • Organisms use calcium carbonate in their shells and skeletons • When they die, they sink to the bottom. • Calcium carbonate precipitates into the water the cements the grains of carbonate sediment.
Organic Sedimentary Rocks • Biogenic - (bio = ?; genic = ?) • Formed from the remains of once-living plants - coal • Plants in swamps and coastal areas die are buried and compressed. • Lithified into coal • Why is it called a Fossil fuel?