Rocks A. Rocks are made up of crystals from different minerals B Rocks A. Rocks are made up of crystals from different minerals B. Rocks can also be made from ancient shells and plants C. 3 types of rocks: Igneous, Sedimentary, and Metamorphic Rock Cycle: changes that rocks undergo, each type can become the other two types. Click in box to play movie.

What are Igneous Rocks: Chapter 5.1

Igneous Rock: comes from the Latin word for fire. Forms hot, from magma. Original rock of the Earth – since the Earth formed hot. Extrusive –fine grained, cool quickly, found on the Earth’s surface Intrusive - coarse grained, cool slowly below Earth’s surface Coarse grains Granite – Intrusive rock Obsidian – Extrusive rock

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B. Mineral Composition Felsic Rocks Light color High silica content Ex: quartz, feldspar Mafic Rocks a. Dark color b. Low in Silica, high in iron and magnesium. c. Ex: diorite, basalt 3. Ultramafic Rocks a. Dark color. b. Low in silica, VERY high in iron and magnesium. c. Ex: peridotite, dunite Pumice – extrusive FELSIC rock Basalt – extrusive MAFIC rock

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Formation of Sedimentary Rocks Chapter 6.1

A. Formed from sediments (pieces of solid material deposited on earth’s surface. 1. Weathering, Erosion, Deposition, and Lithification produce sediments Watch animation

a.. Weathering – physical and chemical processes that break rock into smaller pieces. 1. Chemical – minerals are dissolved or chemically changed a. Less stable minerals are broken down. b. Resistant grains are broken off. 2. Physical –chemically unchanged, fragments are breaking off = Clastic sediments a. Broken b. Pieces usually have worn surfaces and rounded corners.

b. Erosion Removal and movement of surface materials from one location to another. Four main agent a. Wind b. Moving water c. Gravity d. Glaciers Sediments are almost always carried DOWNHILL. c. Deposition 1. Sediments laid down, or sink to bottom of bodies of water.Happens when transport STOPS. 1. Wind stops blowing 2. River enters ocean 2. Sorted –form layers with largest grains on the bottom 3. Unsorted –Mixed layers of grains a. Glaciers b. landslides

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Lithification – Bottom layers have upward pressure and temperature, form rocks that are cemented together

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B. Importance of Sedimentary Rock a. Reconstruction of Earth’s surface at various times in Geologic History. i Fossils ii. Location and direction of ancient rivers. iii. Wave and wind direction iv. Sediments indicate type of bedrock they came from. b. Energy Resources – deposits of coal, natural gas, and oil. Click in Box to Play Movie

Metamorphic Rock Chapter 6.3

Causes of Metamorphism Means “change in form” Forms from pressure and high temperatures 1. Rocks do not reach melting point. 2. Rocks change, but remain solid. 3. Heat comes from the earth’s internal heat or nearby intrusions of igneous rock. 4. Pressure comes from vertical pressure of rock above, or compression during mountain building

1. Types of Metamorphism a. Regional – high temperature and pressure affect LARGE regions of the earth’s crust. i. Low grade, intermediate grade or high grade. ii. Knowing temperatures regions experienced help geologists find valuable minerals. b. Contact- Molten rock comes in contact with solid rock c.Hydrothermal – occurs when very hot water reacts with rock and alters the rock chemistry a. Near active volcanoes b. Igneous intrusions.