Rock Cycle-Part 2

Rock Cycle-Part 2

By Restie Carullo

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Open Ended

Why do we have three classifications of rocks? This is based on what?

​Geologists put rocks into three main groups based on how they form. These groups are igneous rock, sedimentary rock, and metamorphic rock. Igneous rock forms when melted rock cools and hardens. Sedimentary rock is made of pieces of other rock (sediment). Metamorphic rock forms when heat and pressure change the chemical composition of a rock.

​Composition

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​Igneous rocks

could be:

-granitic/felsci

-andesitic/

intermediate​

-basaltic/mafic

-ultramafic​

Multiple Choice

Peridotite in terms of composition is:

• granitic

• andesitic

• basaltic

• ultramafic

​Texture is defined as the sizes, shapes, and positions of the grains that make

up a rock. It could be glassy, fine, coarse and very coarse.

The texture of an igneous rock depends on how fast the melted rock cools. As melted rock cools, mineral

crystals form. When melted rock cools quickly, only very

small mineral crystals can form.​

Multiple Choice

When melted rock cools slowly, large crystals can form, which make a coarse-grained igneous rock.

• True

• False

Texture is affected by the environmet of formation.​

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Multiple Choice

Which of the following is/are TRUE?

• Coarse-grained rocks are plutonic.

• Fine-grained rocks are volcanic.

• both

​Composition is NOT a big deal for inorganic sedimentary rocks. It emphasizes much on the grain size.

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Chemical-when minerals crystallize out of water. As water moves over rocks, it dissolves some minerals in rocks. When the water evaporates, the dissolved minerals can crystallize to form Chemical sedimentary rocks.

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Organic-forms from remains of plants and animals

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Multiple Choice

Limestone makes up the Pyramid of Giza. Can we consider limestone a mineral?

• Yes

• No

​In metamorphic rocks the chemical composition of the rock changes even though the rock is solid.

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Regional Metamorphism-high pressures and temperatures cause the rock in a large area to change

​(Convergence B.)

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Multiple Choice

The transformation of shale to gneiss is an example of regional metamorphism.

• Yes

• No

Contact Metamorphism- happens when rock is heated by nearby magma only affects rocks in small area.​

Activity 4: Petrology Charts in Action