Presentation on theme: "Warm Up The igneous rock texture that is characterized by two distinctly different crystal sizes is called ____. a. porphyritic texture c. fine-grained."— Presentation transcript:
1Warm UpThe igneous rock texture that is characterized by two distinctly different crystal sizes is called ____.a. porphyritic texture c. fine-grained textureb. glassy texture d. coarse-grained textureIgneous rocks that crystallize from magma and are composed almost entirely of quartz and feldspars have a(n) ____.a. andesitic composition c. ultramafic compositionb. basaltic composition d. granitic compositionA rock that forms when magma hardens beneath Earth’s surface is called an ____.a. intrusive metamorphic rockb. extrusive igneous rockc. intrusive igneous rockd. extrusive sedimentary rockAnswers: 1) a. 2) d. 3) c.
3Weathering, Erosion, and Deposition Weathering is any process which breaks rocks into sedimentsErosion 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
5Compaction and Cementation Compaction and cementation change sediments into sedimentary rocksCompaction is a process that squeezes, or compacts, sedimentsCompaction is caused by the weight of sedimentsCementation takes place when dissolved minerals are deposited in the tiny spaces among the sediments.
7Concept CheckWhat are the five major processes involved in the formation of sedimentary rocks?Weathering, erosion, deposition, compaction, and cementation
8Classification 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 mineralsChemical Sedimentary Rocks – forms when dissolved minerals precipitate from water solutions
9Clastic vs. Chemical Sedimentary Rocks Clastic Sedimentary Rocks
11Concept Check What are the major types of clastic sedimentary rocks? Conglomerates and breccia, sandstone, shale and siltstone
12Sedimentary 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 sedimentationThe oldest layers are found at the bottom and the youngest layers are found at the topSome fossils are unique to certain sedimentary rocks; they can answer questions as to where that rock formed and how old they are