Types of Rocks Objective #1: Describe and classify igneous rocks Agenda: Journal entry: What does the word igneous mean? How do igneous rocks form? 2. Review webquest and directed reading 3. Notes on igneous rocks 4. Identify and describe samples

There are 3 Major Rock Groups

Rocks are made of minerals and make up Earth’s solid crust There are 3 Major (Geologic) Rock Groups Not the Rolling Stones, Kiss, or Van Halen 1. Igneous Rock 2. Sedimentary Rock 3. Metamorphic Rock Rocks are made of minerals and make up Earth’s solid crust

Identifying Rocks Igneous pattern Metamorphic pattern Sedimentary pattern

Basalt lava (glowing rock) oozes over basalt lava flow A. Igneous Rock -Forms when a hot, molten liquid, below ground, called magma, crystallizes (cools and solidifies). Magma forms 3 ways: Rock is heated Pressure released Change composition Holt Online Visual: Comparing Int. & Ext Igneous Rocks Basalt lava (glowing rock) oozes over basalt lava flow

Intrusive Igneous Rock -Forms or crystallizes inside Earth -slow cooling

b. Extrusive Igneous Rock -Forms on surface (exterior) of Earth -Fast cooling

a. Composition of Igneous Rock Felsic Rock -Light colored -made of aluminum, potassium, silicon, and sodium. Mafic Rock -Dark colored -Made of calcium, iron, and magnesium. Fine-grained Course-grained Course-grained Fine-grained

b. Texture of Igneous Rock -Slow cooling forms large crystals. (Coarse-grained Texture) -Fast cooling forms small crystals. (Fine-grained Texture)

-Rate of cooling influences crystal size. Fast cooling = small crystals Slow cooling = large crystals Show Holt Visual: Igneous Rock Texture

Pop Quiz! What size crystal forms from extrusive rock? What is one way magma forms? Generally speaking what color are felsic rocks? 4. Quality of rock based on the size, shape, and arrangement of grains is referred to as… 5. What are the 2 characteristics that geologist study to identify rock:?

Igneous Rocks Rock ID practice Use the rock key to identify the various rocks on your table: Igneous Rocks Classified according to composition & texture Glassy- shiny and look like glass, not organized into crystals. Ex: obsidian (volcanic glass)

Fine-grained-made of interlocking crystals. Ex: basalt - the most common extrusive igneous rock BASALT

More Igneous Rocks… Course Grained Texture= Granite

More Igneous Rocks… Porous- no crystals, cools rapidly, looks like a sponge. Ex: pumice

More Igneous Rocks… Diffferent size crystals locked together

More Igneous Rocks…

Sedimentary Rock *There are 3 types of sedimentary rocks. *Often times, sand, mud, pebbles, or shells settle out in wind and water, get compacted and/or cemented together, and harden into rock. Here, rocks hardened in layers called strata from a process known as… stratification.

3 Types of Sedimentary Rock 1. Clastic -forms when rock or mineral fragments are cemented together.

2. Chemical forms when minerals crystallize out of solution, such as sea water, to become rock.

3. Organic forms from the remains of once-living plants and animals. Ex: Limestone Coal Chalk

Metamorphic Rock -Rocks that have undergone a change in texture, structure, or composition. -Changes in heat and pressure cause rocks to change from one form to another.

Origins of Metamorphic Rock

Contact Metamorphism Rock undergoes metamorphism when it comes in contact with magma or is heated by nearby magma.

Regional Metamorphism -Pressure builds up in rock that is buried deep below rock formations or when large pieces of rock collide.

Textures of Metamorphic Rock Foliated the texture of metamorphic rock in which the mineral grains are arranged in planes or bands.

Nonfoliated -The texture of metamorphic rock in which the mineral grains are not arranged in planes or bands.

Rocks are made, destroyed, and created again, in a process called the Rock Cycle