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Chapter 6 Sedimentary rocks. Chapter 6 Section 1 Objectives. Sequence the formation of sedimentary rocks Explain the process of lithification Describe features of sedimentary rocks. Weathering Types. Mechanical/Physical Breakdown of rock Does not change the rock’s composition
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Chapter 6 Section 1 Objectives • Sequence the formation of sedimentary rocks • Explain the process of lithification • Describe features of sedimentary rocks
Weathering Types • Mechanical/Physical • Breakdown of rock • Does not change the rock’s composition • Only changes size and shape • Chemical • Changes the chemical composition of rocks • Acid rain, rust, calcite*
Formation of Sedimentary Rocks • Weathering and Erosion • Breakdown of rocks = weathering • Small particles of rocks = sediments • Particles range from really small to very large • Movement of sediments = erosion • Deposition • Sediments have been carried then deposited • Larger sediments deposit first
Lithification • Sediments are turned into sedimentary rocks • Compaction • Particles pushed together due to more and more deposition • Water and air gets squeezed out • Cementation • Minerals grow and cement compressed particles together
Sedimentary Features • Bedding • The making of layers that go horizontal in the rocks • Graded bedding • Small particles layer at the top of a layer • Larger particles layer are at the bottom layer • Cross bedding
Ripple marks • Small ridges made by wind, waves or river current • Sorting and Rounding • Harder minerals generally take long to break apart • When sediments move they break apart and get rounded
Chapter 6 Section 2 Objectives • Describe the types of clastic sedimentary rocks • Explain how chemical sedimentary rocks form • Describe biochemical sedimentary rocks
Types of Sedimentary rocks • Clastic • Rocks made of particles of other rocks • Coarse grained • Gravel sized particles • Medium grained • Sand sized particles • Fine grained • Silt/clay size particles
Chemical and Biochemical • Result due to evaporation and precipitation of minerals • Chemical Sedimentary Rocks • Crystals precipitate out due to saturation • Crystals settle on the bottom • Called evaporites
Biochemical • Formed from the remains of once living things • Shells settle on bottom are buried • Lithification then occurs • Water gets pushed out • Rocks like limestone are made
Chapter 6 Section 3 Objectives • Compare and Contrast the different types and causes of metamorphism • Distinguish among metamorphic textures • Explain how mineral and compositional changes occur during metamorphism • Apply the rock cycle to explain how rocks are classified
Recognize metamorphic rocks • Metamorphism = to change • Changes result due to heat and pressure • High heat needed for metamorphism comes from the earths interior
Metamorphic Textures • Foliated • Rocks that have undergone great pressure • Cause mineral to be compressed • This compression causes rocks to have layers • Non-Foliated • Rocks that have undergone great pressure and heat
Types of Metamorphism • Regional • High temperatures and pressure affect an entire area • Contact metamorphism • Magma comes into contact with already existing rocks changes the existing rocks • Hydrothermal metamorphism • Hot water reacts with rocks • Gold, copper, zinc, and lead are formed this way
Economic Importance of Metamorphic Rocks • Trade materials…Gold, silver, copper and lead • Building materials…marble, slate