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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.
+
+ +
=
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
D
e
n
s
e
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.