Ch. 10 Rocks & The Rock Cycle

The Parent Material for all rock is…..

Magma!!!

3 Major Types of Rock

• Igneous Rock: forms when magma cools and hardens.

• Sedimentary Rock: forms from sediment that is compacted and cemented together.

• Metamorphic Rock: forms from rock that is changed by intense heat and pressure.

The Rock Cycle• All of the changes that can occur to rock.

• Does Igneous Rock always have to become sedimentary rock?

• Before becoming sedimentary rock, what must metamorphic rock become???

• What processes result in rock turning into sediment?

Igneous Rock

Classified into two general categories based on where the magma cooled and solidified:

1. Intrusive Igneous Rock: Magma cooled below the crust

2. Extrusive Igneous Rock: Magma cooled rapidly on the surface of Earth

Texture of Igneous Rock• What influences texture? The size of crystals found in the rock.

• What influences crystal size? Cooling rate (how fast the magma cooled)

• Cooling slowly allows large crystals to form. • Cooling rapidly allows small crystals to form.

• Intrusive Igneous rock cools slowly. • Extrusive Igneous rock cools very rapidly.

Which type of Igneous rock would have small crystals?

Which type of Igneous rock would have large crystals?

• Crystals formed in sample A might be found in what type of rock?

• Crystals formed in sample B might be found in what type of rock?

Sample A Sample B

What about igneous rock that doesn’t seem to have crystals???

• Silica-rich, viscous, felsic lava that cools rapidly forms Obsidian (Volcanic Glass)

• Magma that has a high amount of dissolved gasses and cools rapidly forms “pockets” or holes around the trapped gas. This creates a rock full of small holes such as pumice.

Composition of Igneous Rock

• Determined by the chemicals found in the magma that forms the rock.

Three types of igneous rock families:1. Felsic: High in silica, these contain silicate minerals

2. Intermediate: intermediates between mafic and felsic chemical composition

3. Mafic: Low in silica, but rich in iron and magnesium.

Types of Igneous Rock Structures

1. Intrusions: igneous rock masses that form underground.

2. Extrusions: igneous rock masses that form on the surface.

Igneous Rock StructuresFill In the names of the structures on your diagram.

Sedimentary Rock

• Review Question: How was sedimentary rock formed???

3 Types of Sedimentary Rock

1. Clastic Sedimentary Rock2. Chemical Sedimentary Rock3. Organic Sedimentary Rock

Clastic Sedimentary Rock• Deposits of rock fragments are compacted and

cemented together.

• Classified by size of sediment that forms the rock. – Conglomerate: rounded gravel sized fragments– Sandstones: made of sand size grains– Shale: clay sized particles

Sandstone

Shale

Chemical Sedimentary Rock

• Rocks that form from minerals once dissolved in water.– Precipitates: Rocks formed from minerals that

solidify in water– Evaporites: Rocks formed from minerals left

behind when water evaporates.

Organic Sedimentary Rock

• Formed from the remains of once living organisms. – Examples:• Coal- forms from decayed plants and animals• Limestone- forms from the shells of once living

organisms

Sedimentary Rock Features

• Stratification: Layering of rock• Ripple Marks: formed by wind or water• Mud Cracks: formed when muddy deposits

dry and shrink• Fossils: remains or traces of once living

organisms • Concretions: nodules with in the rock that are

composed of different chemicals.

Metamorphic Rock• Existing rock that is changed into another

form by intense heat and pressure• Forms deep beneath the surface of earth.

Two Types of metamorphism

1. Contact metamorphism2. Regional metamorphism

Contact Metamorphism

• When hot magma pushes through rock, the heat from the magma can change the surrounding rock.

Regional Metamorphism

• Occurs during tectonic activity

• This plate movement creates heat and pressure at plate edges.

• This heat and pressure transforms the surrounding rock

Classification of Metamorphic Rock

• Metamorphic Rocks are classified according to texture.

Metamorphic Rock Classifications1.Foliated: have parrallel bands

of minerals2.Nonfoliated: metamorphic rock

without mineral bands

Foliated

Nonfoliated

THE END!!!