Q. How do we know about the Earth s history? A. The ROCKS tell us stories
Q. What happened here?
Q. What happened here?
Q. What happened here?
Vocabulary word: Uniformitarianism the scientific rule that what is happening now has happened the same way in the past and will happen the same way in the future. In other words, the rules don t change!
Three Types of Rocks Igneous: Fire rocks that cool from molten rock called magma. Sedimentary: Deposited rocks that form from layers of material that are pressed and cemented together. Metamorphic: Rocks that have changed their form by being heated and crushed.
Three Types of Rocks All rocks are categorized by 1) Their origin: how were they formed? 2) Their chemical composition: what are they made of?
Igneous comes from the word ignite, or burn Igneous rocks are fire rocks from inside the Earth!
If Igneous are fire rocks from inside the Earth, what is inside the Earth?? Remember that when the Earth first formed from colliding meteors, the kinetic energy of the flying meteors was turned to thermal energy. The early Earth was a large, molten ball.
If Igneous are fire rocks from inside the Earth, what is inside the Earth?? Different materials were sorted out by DENSITY. Iron sank to the center and formed the inner and outer core. The mantle is made up of iron and silica. This is where magma is born. And the rocks that were mostly silica floated to the top and became our continents.
Like all rocks, igneous rocks may be sorted 1) by their chemical makeup, 2) and how they were formed.
Chemical makeup: There are two main groups of igneous rocks based on how much iron and silica they have.
Chemical makeup: Granitic (felsic) igneous rocks have a lot of Feldspar and They do not have a lot of iron. Silica
Chemical makeup: Granitic (felsic) igneous rocks are light colored and light weight like this Granite (see the grains?)
Chemical makeup: Basaltic (mafic) igneous rocks have a lot of Magnesium and Iron (Ferrous)
Chemical makeup: Basaltic (mafic) igneous rocks are dark colored and dense like this Basalt
Like all rocks, igneous rocks may be sorted 1) by their chemical makeup, 2) and how they were formed.
For igneous rocks, how they were formed means, did they cool quickly or slowly?
Intrusive igneous rocks cool very slowly underground they are formed from MAGMA. They intrude between other rocks. Because they cool so slowly underground, the crystals have time to grow very large
Extrusive igneous rocks cool very quickly in the air they are formed from LAVA. They exit from the ground. Because they cool so quickly, the crystals don t have time to grow very large some extrusive rocks do not have any crystals at all!
Here are two granitic rocks with the same chemical composition: Granite is an intrusive rock that has cooled slowly for many years. Notice the large crystals. Rhyolite has cooled quickly above the ground (Extrusive) and has very small crystals.
Igneous Vocabulary: Igneous: rocks that crystallize from molten rock. Magma: Lava: Intrusive: Extrusive: molten rock underground. molten rock above ground. igneous rocks that push their way into existing rock and cool underground. They have larger crystals from cooling slowly. igneous rocks that come out of the ground and cool on the surface. They have small or no crystals from cooling quickly.
Igneous Vocabulary: Felsic: igneous rocks with a lot of feldspar and silica. They are light colored and have low density, like granite. Mafic: igneous rocks with a lot of magnesium and iron. They are dark colored and have high density, like basalt.
Sedimentary rocks are made from bits of material called sediment that have been deposited by wind, water and gravity, and then compacted and cemented into new rocks.
Sedimentary rocks have features that no other type of rock have: The most important feature is the layers of rock, called strata. No other type of rock has strata. Strata tell us which rocks are older.
The most important feature is the layers of rock, called strata. No other type of rock has strata. Strata tell us which rocks are older. Which layer do you think is the oldest? The youngest?
The most important feature is the layers of rock, called strata. No other type of rock has strata. Strata tell us which rocks are older. Which layer do you think is the oldest? The youngest?
The most important feature is the layers of rock, called strata. No other type of rock has strata. Strata tell us which rocks are older. The story of the strata would not make sense without the law of super position, which states that newer strata form above older layers
The most important feature is the layers of rock, called strata. No other type of rock has strata.
The most important feature is the layers of rock, called strata. No other type of rock has strata.
The most important feature is the layers of rock, called strata. No other type of rock has strata.
Other features of sedimentary rocks: Fossils: evidence of living things. Shells, bones, footprints. Mud cracks: evidence of dried puddles and lakes
Other features of sedimentary rocks: Rain drops in mud. Ripple marks from dried shores.
No other type of rock would have these, because igneous and metamorphic rock have been crushed and melted and re-crystallized
All rocks are categorized by 1) Their origin: how were they formed? 2) Their chemical composition: what are they made of?
For sedimentary rocks, this means: Clastic rocks, which are formed of pieces of other rocks that have been blown by the wind or washed downstream by water. Size matters! Sandstone Conglomerate.
For sedimentary rocks, this means: Chemical rocks, which are formed when water evaporates and leaves chemicals behind. An example is rock salt, called halite. Limestone can also form this way.
For sedimentary rocks, this means: Organic rocks, which are formed of the remains of plants and animals. An example would be coal from dead plants. Another example would be organic limestone from seashells. Limestone is CaCO 3 what would acid rain do to it?
Sedimentary Vocabulary: Sediment: bits of material that settle to the ground Strata: layers of sedimentary rock Super position: the law that states that new strata form on top of older strata
Sedimentary Vocabulary: Deposition: putting down material see a demo of deposition Compaction: squeezing material together Cementation: gluing together material with minerals that are dissolved in the water see an illustration of cementation Lithification: turning to stone
Metamorphic comes from the word morph, or change shape Metamorphic rocks are rocks that used to be something else!
All rocks are categorized by 1) Their origin: how were they formed? 2) Their chemical composition: what are they made of?
For Metamorphic rocks, this means, 1) what were the rocks before they were changed, 2) how and how much were they changed? Pressure and / or Heat
For Metamorphic rocks, this means, 1) what were the rocks before they were changed, 2) how and how much were they changed? Pressure and / or Heat
Examples: Granite can be smooshed into Gneiss
Examples: Slate can be squeezed into Schist
Examples: Limestone can be squeezed into Marble
Metamorphic Vocabulary: Metamorphism: to change shape Contact metamorphism: rocks changed by being cooked by contact with magma or lava See a photo here Foliation: from foliage, what look like the leaves of a book in a metamorphic rock
Metamorphic Vocabulary: Density: how could a rock become more dense?
This is all there is! The Rock Cycle Apollo 8 Everything on Earth is recycled.
The Rock Cycle Water Is recycled. Apollo 8
Carbon Is recycled. The Rock Cycle
The Rock Cycle And Rock Is recycled. Apollo 8
And Rock Is recycled. The Rock Cycle Weathering, erosion and deposition make new sedimentary rock from old sedimentary, igneous and metamorphic rock. Heat and pressure make new metamorphic rock from old sedimentary, igneous and metamorphic rock. Heating and cooling make new igneous rock from old sedimentary, igneous and metamorphic rock.
And Rock Is recycled. The Rock Cycle Every type of rock can be recycled into every other type of rock!