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3 Types of Rocks. How Igneous Rocks Form:. When molten rock (lava) cools and becomes solid Intrusive: cools slowly Extrusive: cools quickly. Description of Igneous Rocks:. Contains bubble-like holes Hard Bubbly texture Formed above or below earth’s surface. Examples of Igneous Rocks:.
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How Igneous Rocks Form: • When molten rock (lava) cools and becomes solid • Intrusive: cools slowly • Extrusive: cools quickly
Description of Igneous Rocks: • Contains bubble-like holes • Hard • Bubbly texture • Formed above or below earth’s surface
Examples of Igneous Rocks: • Granite • Basalt • Pumice
Uses of igneous rocks • For tools and building material • Granite is used in kitchens • Basalt is used in construction and gravel. • Obsidian is used to make sharp tools
How Metamorphic Rocks Form: • When heat and pressure cause older rocks to change into new types • Formed deep in the earth
Description of Metamorphic: • Fine texture • Has bands or streaks of minerals • Usually made of quartz and calcite • Foliated – banded • Non-foliated- arranged randomly
Examples of Metamorphic: • Marble – comes from limestone • Slate – comes from shale • Quartzite – comes from sandstone
Uses of metamorphic rock • Building and sculpture. • Lincoln memorial in Washington DC is made of white marble. • Slate is used for many purposes such as outdoor walkways, chalkboards, roofing, and flooring.
How Sedimentary Rocks Form: • When rocks, plants, and loose material get pressed into layers over time • Involves weathering and erosion
Description of Sedimentary: • Has layered features • Very soft (easily scratched) • Contains fossils • Made of particles cemented (pressed) togethe • There are three major groups of sedimentary rocks: Clastic, organic and chemical.
Sedimentary Examples: • Limestone – made from seashells • Shale – made from mud • Sandstone – made from sand
Uses of sedimentary • Building and tools • The White House in Washington D.C. is made of limestone and sandstone. • Limestone is also used in making steel and cement.
Discussion questions • Gneiss is a kind of rock that forms from heat and pressure inside earth’s crust. What group would Gneiss belong in and why? • Would pumice make a good floor? Why or why not? • The particles of sediment that make up shale are not usually cemented. Would shale be a good building material? Why or why not? • What would be more useful for carving chess pieces- marble or slate? explain.