Types of Rocks Thursday 9/30 Objective: Describe and classify igneous rocks Agenda: 1.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

3 Major Rock Groups

3 Major (Geologic) Rock Groups Igneous Rock Sedimentary Rock Metamorphic Rock

Identifying Rocks Igneous pattern Metamorphic patternSedimentary pattern

A. Igneous Rock - Forms when hot, liquid, magma crystallizes (cools and solidifies). Magma forms 3 ways: 1. Rock is heated 2. Pressure released 3. Change composition Basalt lava (glowing rock) oozes over basalt lava flow Holt Online Visual: Comparing Int. & Ext Igneous Rocks

a. Intrusive Igneous Rock -Forms inside Earth -slow cooling

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

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

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! 1. What size crystal forms from extrusive rock? 2. What is one way magma forms? 3. Generally speaking what color are felsic rocks? 4. Quality of rock based on the size, shape, and arrangement of grains is shape, and arrangement of grains is referred to as… referred to as… 5. What are the 2 characteristics that geologist study to identify rock:? study to identify rock:?

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

Fine-grained-made of interlocking crystals. Ex: basalt BASALT

More Igneous Rocks… Course Grained Texture- Granite

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

Diffferent size crystals locked together More Igneous Rocks…

Sedimentary Rock Strata layers of rock. Stratification The process in which sedimentary rocks are arranged in layers. Holt Visual Sedimentary Rock Cycle

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