Sedimentary Rocks • Sedimentary rocks are products of mechanical and chemical weathering of preexisting rocks • They account for about 5% (by volume) of Earth’s outer 15 kilometers • The account for 90% of the upper ½ kilometer • Contain evidence of past environments • Provide information about sediment transport by one of the geologic fluids • Often contain fossils
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Sedimentary Rocks Sedimentary rocks are products of mechanical and chemical weathering of preexisting rocks They account for about 5% (by volume) of Earth’s.
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Sedimentary Rocks
• Sedimentary rocks are products of mechanical and chemical weathering of preexisting rocks
• They account for about 5% (by volume) of Earth’s outer 15 kilometers
• The account for 90% of the upper ½ kilometer• Contain evidence of past environments
• Provide information about sediment transport by one of the geologic fluids
• Often contain fossils
Sedimentary rocks are important for economic considerations because
they may contain
• Coal• Petroleum and natural gas• Sources of iron, aluminum, and manganese• Natural fertilizers • Materials for concrete and bitumen
Types of sedimentary rocks
• Sediment originates from mechanical and/or chemical weathering
• Rock types are based on the source of the material
• Detrital or clastic rocks – transported sediment as solid particles• Chemical rocks – sediment that was once in
solution
What is a sediment?
• A material deposited by one of the geologic fluids (wind, water, ice) at the earth’s surface.
Types of Sediments
• Clastics – Materials transported and deposited by wind,
water, or ice
• Chemical– Materials deposited by chemical precipitation
• Biologic – Parts of living organisms
Clastic or Detridal
• Pieces of solid stuff transported ad deposited by a geologic fluid