Objectives:

Define rocks

Describe the rock cycle and some changes that a rock could undergo.

2-1 F

Rocks are a mixture of minerals, glass, organic

matter, and other natural materials.

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feldspar

hornblende

micaquartz

Granite

a. weathering

b. erosion

c. compaction

d. cementation

e. melting & cooling

f. heat & pressure

Rocks are changed by processes such as:

Three types of rock

1. Igneous rock

2. Metamorphic rock

3. Sedimentary rock

Many times transformations are interrupted.This is an example of an igneous rock

interrupted before completely transforming into a metamorphic rock.

Here is a map showing the United States and part of Canada and Mexico. This map

shows what type of rock makes up the surface of these regions

“Hmmm…” said the doc. ‘That’s not a great shock.

You were just becoming a sedimentary rock.”

Three little rocks went to the doc.

The first said, “Doctor, please!

On the ocean floor, washed down from the shore,

I was squished and squashed and squeezed.”

The second said, “Doc, I was boiling hot,

Deep down inside the planet,

But then I was pushed, cooled off, and smushed,

And now I feel like granite.”

“Hmmm…” said the doc. “Don’t be a worrywart,

You’ve turned into stone of the igneous sort.

The third said, “Doc, I started as a rock,

Just like these other two,

I was under great stress, I’m a flattened mess,

What I am now, I haven’t a clue.”

“Hmmm…” said the doc. “Your condition’s well known.

It’s obvious now you’re a metamorphic stone.”

“Thank you, Doc!” said each little rock,

Wearing a happy smile,

Then one by one,

they rolled out in the sun

And sat there in a pile.

Objectives:

. Recognize magma and lava as the materials that cool to form igneous rocks.

•Contrast the formation of intrusive and extrusive igneous rock.

•Contrast granitic and basaltic igneous rocks.

2-2F

Comes from molten material.

It can be intrusive or extrusive. Molten rock under Earth’s surface is less dense & is forced upward. If it cools under the surface it forms intrusive igneous rock. The slower the cooling process, the larger the crystal grains.

Laccolith

Batholith

Forms when lava hardens on or near Earth’s surface.

It cools quickly and produces fine grained crystals.

(ex. Pumice, Obsidian)

pumice

obsidian Classification of Igneous Rock

Basaltic rocksDark gray to black

Fine grained

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GraniticGranitic igneous rocks are light colored and less dense than basaltic rocks.

Andesitic

Andesitic rocks have compositions between granitic and basaltic.

Igneous rock is the most abundant rock on Earth.

Objectives:

Describe conditions that cause metamorphic rocks to form.

Classify metamorphic rocks as foliated or nonfoliated.

2-3F

Rocks that have changed due temperature and pressure. They can be formed from igneous, sedimentary, or other metamorphic rocks.

Examples

Granite changes

to gneiss

Limestone changes to marble

Shale changes to slate

Classification

(according to texture)

Foliated texture – line up in parallel bands

slate gneiss

Non-foliated rocks –no bands occur

marble

quartzite

Objectives:

Explain how sedimentary rocks form from sediments.

Classify sedimentary rocks as detrital, chemical, or organic.

Summarize the rock cycle.

75% of the rocks on Earth’s surface are sedimentary rock.

Sedimentary rocks are formed when sediments are pressed and cemented together, or when minerals form from solutions.

Detrital Sedimentary Rocks are made by broken fragments of eroded rocks.

Detrital rocks are formed by the process of compaction and cementation

Compaction layer upon layer of sediments

build up

Pressure from upper layer pushes down

Sediment sticks together

Solid rock

Cementation Large pebbles & sand

Water soaks through

Dissolves minerals in rock

Forms a natural cement

Chemical Sedimentary Rock

Chemical sedimentary rock are from dissolved minerals in a solution.

Limestone

Rock Salt

Organic Sedimentary Rock

Rocks made up of once living things are called organic sedimentary rock. Animal shells make up natural chalk.

Coal is made of decayed swamp plants.