igneous rocks

IGNEOUS ROCKS

Pg 99 text book

http://my.hrw.com

What you will learn

• Describe three ways that igneous rock forms. • Explain how the cooling rate of magma affects

the texture of igneous rock. • Distinguish between igneous rock that cools

within Earth’s crust and igneous rock that cools at Earth’s surface.

Igneous rock begins as magma

What is the origin of Igneous Rock?

http://www.webquest.hawaii.edu/kahihi/sciencedictionary/images/magma_flow_up.gif

There are three ways magma can form:

1. when rock is heated,

2. when pressure is released,

3. when rock changes composition.

What are the ways that magma can form?

Put a drawing like this on pg 37 in your nb

The longer it takes for the magma or lava to cool, the more time mineral crystals have to grow.

The more time the crystals have to grow, the larger the crystals.

The larger the crystals are the coarser the texture of the resulting igneous rock is.

What happens

to magma when it cools at different

rates?

The less time magma takes to cool, the less time crystals have to grow. Therefore, the rock that is formed will be fine grained.

What happens

to magma when it cools at different

rates?

Fine-grained igneous rock contains very small crystals, or if the cooling is very rapid, it contains no crystals.

What happens

to magma when it cools at different

rates?

What are the Compositions and Textures

of Igneous Rock?

What are examples of each type?

What is Intrusive Igneous Rock?

Magma that cools and solidifies deep within the Earth’s crust.

What is Intrusive Igneous Rock?

Magma that intrudes, or pushes, into surrounding rock below the Earth’s surface and cools.

What is Intrusive Igneous Rock?

Usually has a coarse-grained texture because it is well insulated by surrounding rock and cools very slowly. The minerals that form are large, visible crystals.

What are the different

masses of intrusive

igneous rock named and

why?

Masses of intrusive igneous rock are named for their size and shape

PlutonsBatholithsStocks Dikes

Plutons are large, irregular-shaped intrusive bodies.

The largest of all igneous intrusions are batholiths.

Stocks are intrusive bodies that are exposed over smaller areas than batholiths.

Dikes sheetlike intrusions that cut across previous rock units.

Sills are sheetlike intrusions that are oriented parallel to previous rock units.

Plutons

Batholiths

Stocks

Dikes

Sills

PLUTONS

Where would I find

Extrusive Igneous Rock?

Magma that erupts, or extrudes, onto the Earth’s surface. Extrusive rock is common around volcanoes.

Lava cools quickly on the surface and contains very small crystals or no crystals.

What type of texture

do extrusive igneous

rock have?

Does lava always

come from volcanoes?

Lava does not always flow from volcanoes. Sometimes lava erupts and flows from long cracks in the Earth’s crust called fissures.

Where do we

find fissures?

Lava flows from fissures on the ocean floor at places where tension is causing the ocean floor to be pulled apart.

When a large amount of lava flows out of fissures onto land, the lava can cover a large area and form a plain called a lava plateau.

Sedimentary Rock

Pg 44 in nbPg 102 in tb

What You Will Learn

• Describe the origin of sedimentary rock. • Describe the three main categories of

sedimentary rock. • Describe three types of sedimentary

structures.

Rock and mineral fragments called sediment

What are the origins of

Sedimentary Rocks?

sediment plume from Moore Creek entering Dog River.

http://www.usouthal.edu/geography/fearn/480page/98Gerrit/SedPlume.html

What are the agents

of weathering that make sediment?

1. Wind2. Water3. Ice4. Sunlight 5. Gravity

How do sediments

move from one place to

another?

Through the process of erosion.

1. Layers of sediment are deposited, they cover older layers.

2. Older layers become compacted.

3. Dissolved minerals separate from water that passes through the sediment.

4. Dissolved minerals form a natural cement

5. Cement binds the rock and mineral fragments together.

How are sedimentary rocks formed?

Sedimentary rock forms at or near the Earth’s surface. It forms without the heat and pressure that are involved in the formation of igneous and metamorphic rocks.

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What is

strata?

Layers of sedimentary

rock.

http://davidkanaga.blogspot.com/2011/07/sediments-and-sedimentary-rocks.html

Sedimentary rock is classified by the way it forms.

Clastic, Chemical, and Organic

How is sedimentary

rock is classified?

Clastic sedimentary rock is made of fragments of rocks cemented together by a mineral such as calcite or quartz.

What is clastic Sedimentary Rock?

By the size of the fragments from which the rock is made.

How is clastic

sedimentary rock is

classified?

Pg 103

Chemical sedimentary rock forms from solutions of dissolved minerals and water.

How is chemical sedimentary rock formed?

Halite, one type of chemical sedimentary rock, is made of sodium chloride, NaCl, or table salt.

What is Organic

Sedimentary Rock and what are

some examples.

Limestone forms from the remains, or fossils, of animals that once lived in the ocean.

Coal forms underground when partially decomposed plant material is buried beneath sediment and is changed into coal by increasing heat and pressure.

fossiliferous limestone

coal

What are some

Sedimentary Rock

Structures?

Stratification is the process in which sedimentary rocks are arranged in layers.

Ripple marks, record the motion of wind and water waves on lakes, oceans, rivers, and sand dunes in features called Structures called mud cracks

ripple marks

http://www.answersincreation.org/curriculum/geology/geology_chapter_6.htm

Mud Cracks

Metamorphic rockspg 106 text

pg 48nb

Origins of Metamorphic

Rock

If the temperature or pressure of the new environment is different from the one in

which the rock formed, the rock will undergo metamorphism.

The word metamorphism comes from the Greek words meta, which means “changed,” morphos, which means “shape.”

Contact metamorphism is a change in the texture or structure of a rock resulting from the contact of invading magmatic material.

Texture and structure of

metamorphic rocks

Texture and structure of

metamorphic rocks

Regional metamorphism is metamorphism that affects rocks over large areas, instead of in only a local area.

107

p107

Hornfels is a fine-grained nonfoliated metamorphic rock with no specific composition. It is produced by contact metamorphism. Hornfels is a rock that was "baked" while near a heat source such as a magma chamber, sill or dike.

http://www.geol.umd.edu/~jmerck/geol100/lectures/16.html

Regional metamorphic area

The minerals calcite, quartz, and hematite combine and recrystallize to form the metamorphic mineral garnet. P.108

Scientists can understand a metamorphic rock’s history by observing the minerals the rock contains. Theses minerals are called index minerals

p108

index minerals,

Textures of Metamorphic

Rock

The texture of metamorphic rock in which the mineral grains are arranged in planes or bands

Foliated.

Textures of Metamorphic

Rock

The texture of metamorphic rock in which the mineral grains are not arranged in planes or bands

Nonfoliated.

The effects of metamorphism depend on the heat and pressure applied to the rock. see what happens to shale, a sedimentary rock, when it is exposed to more and more heat and pressure.

. Pg 109

Metamorphic Rock

Structures

Deformation is a change in the shape of a rock caused by a force placed on it. These forces may cause a rock to be squeezed or stretched.

These large folds occur in metamorphosed sedimentary rock along Saglet Fiord in Labrador, Canada

Slate is a fine-grained, foliated metamorphic rock that is created by the alteration of shale or mudstone by low-grade regional metamorphism

Shale sedimentary rock

Slate metamorphic rock

created by the alteration of shale or mudstone by low-grade regional metamorphism

Gneiss is foliated metamorphic rock that has a banded appearance and is made up of granular mineral grains.

Granite igneous rock

Gneiss metamorphic rock

Marble is a non-foliated metamorphic rock that is produced from the metamorphism of limestone.

Limestone sedimentary rock

Marble metamorphic rock

Quartzite is a non-foliated metamorphic rock that is produced by the metamorphism of sandstone. It is composed primarily of quartz.

Sandstone sedimentary rock

Quartzite metamorphic rock