1. The Rock Cycle

2. Igneous Rock
This type of rock is formed by the melting and cooling of Earth’s materials.
Melting of the Earth’s materials takes place under the surface of Earth’s Crust

3. Igneous Rock Melting of rock comes in two forms: Magma or Lava
Magma is defined as melted Earth material found under the surface of the crust. This is usually found in large pools called batholiths (under inactive volcanoes.)
Lava is defined as melted Earth material that has broken through the surface of the crust. This usually occurs in active volcanoes and deep ocean vents/rifts.

4. Igneous Rock
After the melting process has occurred the cooling then takes place to form the Igneous Rock.
What the rock looks like depends greatly on how long it takes to cool.
When magma or lava cools slowly, crystallization of the rock takes place.
When magma or lava cools quickly, there is no crystallization.

5. Igneous Rock
Crystallized Rock-Slow cooling rock material allows crystals to form-the slower the cooling the larger the crystals.
Here is an example of a Crystallized Igneous Rock
oldearth.org

6. Igneous Rock
Fast cooling magma or lava will form small crystals or no crystals at all. Some may cool so fast that a type of “glass” is formed.
Obsidian is volcanic “glass.”

7. Igneous Rock
Sometimes the cooling has gas bubbles. These bubbles create holes. These holes create a rock that is less dense than water. (This means it can float on water.)

8. Igneous Rock Quick Facts
Considered to be the oldest rock type on Earth.
Rarely contains fossils because of the complete destruction of the materials while melting.
Large deposits have been uplifted to the surface through Plate Tectonics.

9. Igneous Rock
Bear Butte and the Devil’s Tower are examples of large deposits of Igneous Rock that have been uplifted.
Devil’s Tower, South Dakota
Bear Butte, South Dakota

10. Sedimentary Rock
This type of rock is created by rock materials being broken down through erosion and weathering. (It turns into sediment.)
It then gets carried to a place that will sort the materials. (This is called transportation.)
In a place like the ocean, a lake, or pond, the materials start to separate by size and density forming layers at the bottom of the body of water. (This is called deposition.)

11. Sedimentary Rock
The layered materials continues to have materials piled on top of the previous deposit. (This is called burial.)
These layers are then put under an extreme amount of pressure. (This is called compaction.)
The entire process from deposition to compaction is called lithification of rocks.
Sometimes rocks are held together chemically, (This process is called cementation.)

12. Sedimentary Rock
Sediment-broken down rock material that is carried to another place and deposited.
An aerial view of a river carrying sediment to an ocean or gulf.

13. Sedimentary Rock
Transportation-The carrying of sediment from one place to another. This is usually done through the process of the water cycle. It can also happen through wind erosion.

14. Sedimentary Rock
Deposition-Sediment that has been carried by water or air eventually lands or flows in to a place like a lake and begins to settle to the bottom. When this occurs the sediment begins to separate and layer according to the mass of the particles. Higher massed items settle to the bottom first, followed by less dense particles.

15. Sedimentary Rock
Burial-is the covering of potential rock material by more potential rock material.
This is an image of different levels of buried rock material. Burial is one way sedimentary rock gets the layered look.

16. Sedimentary Rock
Compaction-This with is the process of pressing the potential rock material together. Combined with cementation (the “gluing” together of rock) is how the sedimentary rock stays together.

17. Sedimentary Rock
Cementation is another way sedimentary rocks are held together. Certain mixes of minerals and water cause a chemical “glue” to develop. This glue holds sediment, rocks, and sometimes once living things (remains of animals) together causing a rock to form when it hardens.

18. Sedimentary Rock
Weathering-the various mechanical and chemical processes that cause exposed rock to decompose.
Chemical Weathering-changing the chemical and mineralogical composition of the rock. (A chemical reaction takes place.)
Mechanical Weathering-any of the various weathering processes that cause physical disintegration of exposed rock without any change in the chemical composition of the rock. (Breaking, cracking, scratching of a rock into smaller pieces.)

19. Sedimentary Rock Quick Facts
Rock type most likely to have fossils that are accurate in shape, size, and look. (Very little distortion.)
Helps us figure out the relative age of once living things.
Has been used to calculate what types of weather patterns and erosive processes we have had in the past.

20. Sedimentary Rock
The grand Canyon is one of the largest and most popular Sedimentary Rock Deposits in the world.

21. Metamorphic Rock
Metamorphic rock is formed by the heating up of rock material and the application of pressure to those rocks.
Deformation and metamorphosis of the rock occurs.
The heating of the rock takes place near areas on the Earth that have large amounts of friction near them (Tectonic Plate Boundaries)

22. Metamorphic Rock Metamorphic rock is usually formed underground.
Metamorphic rock is also found near magma pools called batholiths.
The term metamorphism means “change.”
Metamorphic rock can have both physical and chemical changes occur while forming.

23. Metamorphic Rock
Heating-When a rock heats up it begins to get soft and is pliable, able to be bent.
There are a few ways rock can be heated and not melted. (Melting is the conversion of a solid into a liquid.)
The first way rock is heated is friction or the rubbing of two objects against each other.
The second way rock is heated is the proximity to lava or magma. The closer to the melted rock material, the more chance it has of heating up.
The third way rock is heated is depth in the crust or its location in the crust. The deeper the rock is buried, the more chance it has to heat up.

24. Metamorphic Rock
The second part of creating metamorphic rock is deformation. When rock materials become flexible the are then weakened. Pressure from the surrounding forces distort what the rock once looked like.

25. Metamorphic Rock Quick Facts
Metamorphic rock processes use other rock forms (and itself) to make metamorphic rock. The process does not include taking other Earth materials (non-rock materials) and creating rock out of it.