Warm Up 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 3

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 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 3 (pg. 75-79) Do Chapter 3 Assessment #1-36 (pg. 89-90) For Section 3: Do #’s 6-8, 15, 16, 24, 25, 29, 30, 31, 32