Types of Rocks

3 Major (Geologic) Rock Groups

Igneous Rock

Sedimentary Rock

Metamorphic Rock

Identifying Rocks

Igneous pattern Metamorphic pattern Sedimentary pattern

A. Igneous Rock

-Forms when _______, _______, _________ crystallizes (cools and solidifies).

Magma forms 3 ways:1. _________________2. _________________3. _________________

Basalt lava (glowing rock) oozes over basalt lava flow

Holt

On

lin

e V

isu

al:

Com

pari

ng

In

t. &

Ext

Ig

neou

s R

ock

s

a. Intrusive Igneous Rock-Forms _________ Earth-_______________________

b. Extrusive Igneous Rock-Forms on _________________ of Earth-___________________________

Felsic Rock-___________________-made of aluminum, potassium, silicon, and sodium.

Mafic Rock-__________________-Made of calcium, iron, and magnesium.

Course-grained Fine-grained

Course-grained Fine-grained

a. Composition of Igneous Rock

b. Texture of Igneous Rock

-________ cooling forms ________crystals. (Coarse-grained Texture)-_________ cooling forms

________ 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 referred to as…5. What are the 2 characteristics that geologist study to identify rock:?

Rock ID practiceUse 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…

More Igneous Rocks…

Sedimentary RockStrata layers of rock.

Stratification The process in which sedimentary rocks are arranged in layers.

Holt V

isual S

ed

imen

tary R

ock

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

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

Regional Metamorphism

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

• Contact Metamorphism– Rock undergoes

metamorphism when it comes in contact with magma or is heated by nearby magma.

Origins of Metamorphic RockOrigins of Metamorphic Rock

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.