RocksRocks

Environmental Science

Earth Science Unit

Questions for TodayQuestions for Today

1. What are Rocks?

2. What are the three types of Rock?

3. How are Igneous Rocks Classified?

4. How are Sedimentary Rocks Classified?

5. How are Metamorphic Rocks classified?

1. What are Rocks?

2. What are the three types of Rock?

3. How are Igneous Rocks Classified?

4. How are Sedimentary Rocks Classified?

5. How are Metamorphic Rocks classified?

RocksRocks

• Rocks are aggregates of minerals that are held together to form a consolidated mass.

• The three general types of Rock are:– Igneous– Sedimentary– Metamorphic

• Rocks are aggregates of minerals that are held together to form a consolidated mass.

• The three general types of Rock are:– Igneous– Sedimentary– Metamorphic

Igneous RocksIgneous Rocks

• Igneous Rocks are rocks that result from a melt – called magma.

• There are two types of Igneous Rocks:– Plutonic Rocks – form beneath the earth’s

surface.• Coarse Textured• Ex: Granite and Gabbro

– Volcanic Rocks – form above the earth’s surface.

• Fine textured• Ex: Rhyolite, Andesite, and Basalt

• Igneous Rocks are rocks that result from a melt – called magma.

• There are two types of Igneous Rocks:– Plutonic Rocks – form beneath the earth’s

surface.• Coarse Textured• Ex: Granite and Gabbro

– Volcanic Rocks – form above the earth’s surface.

• Fine textured• Ex: Rhyolite, Andesite, and Basalt

Igneous RocksIgneous Rocks

Sedimentary RocksSedimentary Rocks

• Rocks that form near the surface of the Earth through chemical precipitation from water or by cementation of loose fragments (sediments)

• Three types of Sedimentary Rocks:– Clastic – result from cementation of loose fragments.– Chemical - result from direct chemical precipitation from

surface water.• How Halite and Calcite is formed.

– Biogeochemical – result from the chemical precipitation by living organisms.

• Limestone is the most common biogeochemical sedimentary Rock.

• Rocks that form near the surface of the Earth through chemical precipitation from water or by cementation of loose fragments (sediments)

• Three types of Sedimentary Rocks:– Clastic – result from cementation of loose fragments.– Chemical - result from direct chemical precipitation from

surface water.• How Halite and Calcite is formed.

– Biogeochemical – result from the chemical precipitation by living organisms.

• Limestone is the most common biogeochemical sedimentary Rock.

Identifying Clastic RocksIdentifying Clastic Rocks

Name of Particle

Size Range Loose Sediment

Consolidated Rock

Boulder > 256 mm Gravel Conglomerate (if clasts are

rounded) or Breccia (if clasts

are angular)

Cobble 64-256 mm Gravel

Pebble 2-64 mm Gravel

Sand 1/16 -2 mm Sand Sandstone

Silt 1/256 – 1/16 mm

Silt Siltstone

Clay <1/256 mm Clay Claystone, mudstone, and shale

Sedimentary RocksSedimentary Rocks

Metamorphic RocksMetamorphic Rocks

• Rocks that result when any kind of PRE-existing rock is buried deep in the Earth and subjected to HIGH temperature and pressures.

– Most metamorphic rocks show a banded texture of the different sheets of silica

– Examples: Slate and Schist

• Rocks that result when any kind of PRE-existing rock is buried deep in the Earth and subjected to HIGH temperature and pressures.

– Most metamorphic rocks show a banded texture of the different sheets of silica

– Examples: Slate and Schist

The Rock CycleThe Rock Cycle

• Rocks are all interrelated through the processes that form them.

• The Rock Cycle are the interactions of physical and chemical processes that change rocks from one type to another.

– The Rock Cycle is the slowest of the earth’s cyclical processes.

• Rocks are all interrelated through the processes that form them.

• The Rock Cycle are the interactions of physical and chemical processes that change rocks from one type to another.

– The Rock Cycle is the slowest of the earth’s cyclical processes.

The Rock CycleThe Rock Cycle

• The earth’s materials are recycled over millions of years by three processes:

– Melting– Erosion– Metamorphism

• Rocks from any of the three classes can be converted to rocks of the other two classes, or can be recycled within its own class.

• The earth’s materials are recycled over millions of years by three processes:

– Melting– Erosion– Metamorphism

• Rocks from any of the three classes can be converted to rocks of the other two classes, or can be recycled within its own class.

Rock Cycle TermsRock Cycle Terms

• Sedimentary Processes:– Transportation/Erosion– Deposition

• Deposition of eroded material

– Lithification• To become rock, usually through cementation

– Uplift• Exposure of crustal rock to the atmosphere

• Sedimentary Processes:– Transportation/Erosion– Deposition

• Deposition of eroded material

– Lithification• To become rock, usually through cementation

– Uplift• Exposure of crustal rock to the atmosphere

Rock Cycle AnimationRock Cycle Animation

• Interactive Rock Cycle• Interactive Rock Cycle