Warm Up 10/4 The igneous rock texture that is characterized by two distinctly different crystal sizes is called a porphyritic texture c fine-grained texture b glassy texture d coarse-grained texture Igneous rocks that crystallize from magma and are composed almost entirely of quartz and feldspars have a(n) a andesitic composition c ultramafic composition b basaltic composition d granitic composition A rock that forms when magma hardens beneath Earth’s surface is called an a intrusive metamorphic rock b extrusive igneous rock c intrusive igneous rock d extrusive sedimentary rock Answers: 1) a 2) d 3) c Sedimentary Rocks Chapter 3, Section Weathering, Erosion, and Deposition • Weathering is any process which breaks rocks into sediments • Erosion involves weathering and the removal of rock When an agent of erosion – water, wind, or gravity – loses energy, it drops the sediments This process is called deposition • Sediments are deposited according to size • Smaller sediments will travel longer distances Weathering, Erosion, and Deposition Compaction and Cementation • Compaction and cementation change sediments into sedimentary rocks • Compaction is a process that squeezes, or compacts, sediments • Compaction is caused by the weight of sediments • Cementation takes place when dissolved minerals are deposited in the tiny spaces among the sediments Compaction and Cementation Concept Check • What are the five major processes involved in the formation of sedimentary rocks? • Weathering, erosion, deposition, compaction, and cementation Classification of Sedimentary Rocks • Just like igneous rocks, sedimentary rocks can be classified into two main groups according to the way they form • Clastic Sedimentary Rocks – rocks that are made of the weathered bits of rocks and minerals • Chemical Sedimentary Rocks – forms when dissolved minerals precipitate from water solutions Clastic vs Chemical Sedimentary Rocks Chemical Sedimentary Rocks Clastic Sedimentary Rocks Formation of Coal Concept Check • What are the major types of clastic sedimentary rocks? • Conglomerates and breccia, sandstone, shale and siltstone Sedimentary Rock Features • The many unique features of sedimentary rocks are a clue to how, when, and where the rocks formed • Each layer of sedimentary rocks records a period of sedimentation • The oldest layers are found at the bottom and the youngest layers are found at the top • Some fossils are unique to certain sedimentary rocks; they can answer questions as to where that rock formed and how old they are Sedimentary Rock Features Assignment • Read Chapter 3, Section (pg 75-79) • Do Section 3.3 Assessment #1-9 (pg 79) • Print out “Exploration Lab – Rock Identification” for next class! [...]...Concept Check • What are the major types of clastic sedimentary rocks? • Conglomerates and breccia, sandstone, shale and siltstone Sedimentary Rock Features • The many unique features of sedimentary rocks are a clue to how, when, and where the rocks formed • Each layer of sedimentary rocks records a period of sedimentation • The oldest layers are... and the youngest layers are found at the top • Some fossils are unique to certain sedimentary rocks; they can answer questions as to where that rock formed and how old they are Sedimentary Rock Features Assignment • Read Chapter 3, Section 3 (pg 75-79) • Do Section 3. 3 Assessment #1-9 (pg 79) • Print out “Exploration Lab 3 – Rock Identification” for next class!