Types of Rocks Ms. Sikes

Igneous Rocks Form from magma 2 types: Intrusive: (inside) rock formed from magma beneath the earth’s surface Extrusive: (outside) rock formed as a result of volcanic activity at or near earth’s surface

Igneous Rocks cont… Texture is determined by how fast it cools. Slow = coarse (bumpy) texture Fast = fine (smooth) texture

Examples of Igneous Rocks PUMICE OBSIDIAN GRANITE: the most abundant igneous rock

Sedimentary Rocks Formed when sediment (gravel, sand, mud, silt) forms layers and are compacted (smushed) together Forms at the earth’s surface (often in the bottom of lakes and oceans)

Sedimentary Rocks cont… 3 types of Sedimentary Rocks: 1. Clastic- made of rock fragments and cemented together by a mineral like calcite or quartz (these look grainy) (sandstone) 2. Chemical- form from dissolved minerals in water (halite) 3. Organic- form from fossils of animals (coal)

Characteristics of Sedimentary Rocks Usually in layers (strata)

Examples of Sedimentary Rocks See page 373 in book

Metamorphic What does the word metamorphosis mean? Where have you heard it before?

Metamorphic Rocks Were originally sedimentary or igneous rocks Formed when: heat or pressure is different from what the rock is used to and it changes the rock Usually rocks change at temps between 50 degrees Celsius to 1000 degrees Celsius

Ways that rocks can metamorphasize 1. rock is heated by nearby magma 2. pressure builds up in rocks which causes it to change

Texture of Metamorphic Rocks Foliated: mineral grains are arranged in bands Nonfoliated: mineral grains are randomly arranged Marble Slate

Picture tour of book Look on pages 369-380

Classify your rocks Which ones are sedimentary? Which ones are Igneous? Which ones are metamorphic? Can you name any of them?

Exit Ticket On a post it note: Explain how each type of rock is formed: 1. metamorphic 2. sedimentary 3. igneous