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The Rock CycleChapter 4

Key Points Notes

What is a rock?

Composition

Texture


A rock is a naturally occurring solid mixture of one or more minerals or organic matter.

The Rock Cycle


Composition is the chemical makeup of a rock. Composition can describe either the minerals or

other materials in the rock.

The Rock Cycle


Texture based on the sizes, shapes, and positions of the rock’s grains (___________).MINERALS

The Rock Cycle


Metamorphic Rock Formation

Key Points Notes

How are metamorphic rocks

formed?


As rocks undergo metamorphism, original minerals in a rock change into new minerals that are more stable within the new pressure and temperature conditions.




Key Points Notes

Where do metamorphic rocks

form?

Inside Earth’s crust

(some closer to the surface, some much deeper)


Create one diagram to explain contact metamorphism and regional metamorphism


Index minerals are used to estimate the temperature, depth, and pressure at which a rock

undergoes metamorphism in Earth’s crust.




Key Points Notes

Special identifying characteristics of

metamorphic rocks

• Lines of stretched minerals• Specific index minerals



Key Points Notes

2 types of metamorphic rocks

• FOLIATED: Due to pressure, grains (minerals) have been stretched into bands

•NONFOLIATED: Grains (minerals) are randomly placed throughout rock


Identifying Characteristics(how do you know it’s metamorphic?)

Foliated or Nonfoliated

Name of Metamorphic

Rock

Detailed Illustration

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Metamorphic Rock Identification


DO NOW

1) Open your textbook to the igneous rock section

2) Get out your rock cycle notes3) Clear everything else off your

desk


Igneous Rock Formation

Key Points Notes

How are igneous rocks formed?



Igneous rock forms when hot, liquid rock, or magma, cools and solidifies. There are three ways magma can form:

1. When rock is heated

2. When pressure is released

3. When rock changes composition



Key Points Notes

Where do igneous rocks form?

In a volcano or outside a volcano



Key Points Notes

What are the 2 types of igneous rock?



• When magma intrudes, or pushes, into surrounding rock below the Earth’s surface and cools, the rock that forms is called intrusive igneous rock.

• Intrusive igneous rock has a coarse-grained texture because it is well insulated by surrounding rocks and cools very slowly.



• Igneous rock that forms from magma that erupts, or extrudes, on the Earth’s surface is called extrusive igneous rock.

• Extrusive igneous rock, commonly found around volcanoes, cools quickly on the surface and contains very small crystals or no crystals.



•Sometimes, an igneous rock can be both fine and course-grained. These rocks are called porphyritic.

How do you suppose porphyritic rocks are

formed?



Key Points Notes

Special identifying characteristics of

igneous rocks

•Found near a volcano•Visible course-grained minerals that are not foliated (stretched)•Found in a lava flow•Very shiny (teeny-tiny fine-grained minerals)•Vesicles•Glassy•Some tend to be lighter



Key Points Notes

2 types of colors • Light-colored FELSIC rocks are rich in elements such as aluminum, potassium, silicon, and sodium.

• Dark-colored MAFIC rocks are rich in calcium, iron, and magnesium.


Let’s Practice! Igneous Rock Formation

What type of igneous rock is pictured?(composition, location)

Mafic, Fine-grained, Extrusive



What type of igneous rock is pictured?(Composition, location)

Felsic, Course-grained, Intrusive



What type of igneous rock is pictured?(Composition, location)

Felsic, Fine-grained, Extrusive


Igneous Rock Identification

Identifying Characteristics

(how do you know it’s igneous?)

Intrusive or Extrusive?

Name of Igneous Rock

Detailed Illustration

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