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Download Chapter 10 ROCKS
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Chapter 10 ROCKS Ch. 10.1 Rocks and the Rock Cycle • Magma is the parent material for all rocks. • There are three types of rocks, classified by how they are formed. Igneous Rocks • Formed when magma or lava cools and hardens. • Igneous is from the Latin term from fire. Sedimentary Rock • Formed when small fragments of rock or organic material harden after being compressed and cemented together. Metamorphic Rock • Forms when heat and or pressure, or chemical processes change the form of existing rock. The Rock Cycle • Any type of rock can be changed into any other kind of rock and back again. • Processes are… • Melting and cooling—igneous. • Compaction and cementation— sedimentary. • Heat and pressure—metamorphic. Characteristics of Igneous Rocks • Large or small crystals depending on cooling rate. The slower the cooling rate, the larger the crystals. • Color depends on lava or magma type…felsic produces lighter rocks; mafic produces darker rocks. • May have trapped gas bubbles (pumice and scoria). • Generally composed of silicate minerals. Characteristics of Sedimentary Rocks • Form from cemented together rock fragments, organic material, or from minerals that precipitate out of water. • May have layered structure from deposition of various kinds of sediment deposited in silt beds. • Moving wind or water may cause ripple marks. • May contain fossils…remains or traces of ancient plants or animals. Characteristics of Metamorphic Rock • Local volcanism may cause contact metamorphism. • Tectonic activity may cause widespread regional metamorphism. Usually deep within the earth. • May have enlarged or alternating bands of crystals (foliated). • May change soft sedimentary rock into hard, durable rock.
