1. Rocks and the Rock Cycle
AMS 2017

2. How we classify
Over billions of years, rocks have been formed, destroyed, and created by factors that make up the rock cycle.
Rocks are mixtures of minerals and other materials
You must look at the inside of a rock because the effects of water and weather can change the outer surface of the rock.
Geologists observe and classify rocks by
Color
Texture (how something feels)
Mineral composition

3. Cementation of Sediments
3 Types of Rock
They are all formed differently
The can change into one another through the rock cycle
How a rock is formed determines how it is classified.
Igneous
Metamorphic
Sedimentary
Cooled down magma
Heat and Pressure
Cementation of Sediments

4. Rock Cycle

6. Igneous Rock Formed from magma or lava that cools and hardens.
If cooling takes place slowly beneath Earth’s surface, the igneous rock is called intrusive. 
If the cooling takes place rapidly on Earth’s
surface, the igneous rock is called extrusive.
Uses:
Building materials
Basalt used for gravel
Pumice- Used for cleaning

7. Composition Extrusive- Formed from lava; volcanic
Intrusive- Formed deep within the earth
Pumice
Obsidian
Granite

8. Remember, it’s called lava when it is on Earth’s surface, and magma when it is inside the Earth.
Metamorphic Rock
Forms when rocks are changed into different kinds of rocks by great heat and/or pressure when buried deep inside of the earth– they are heated, squeezed, folded, or chemically changed by contact with hot fluids and/or tectonic forces.
When heat and pressure reach the rock’s
melting point, it melts into magma.

9. Granite to Gneiss
Granite (an intrusive igneous rock) becomes gneiss (metamorphic) when subjected to heat and pressure.
The atoms end up lining up in bands.
We call this lining up atoms in bands foliation.

10. Sedimentary
Forms from the compaction and/or cementation of rock pieces, mineral grains, or shell fragments called sediments. This process is called LITHIFICATION.
Sediments are formed through the processes of weathering and erosion of rocks exposed at Earth’s surface.
Sedimentary rocks can also form from the chemical depositing of materials that were once dissolved in water.

11. Lithification The process by which sediment becomes sedimentary rock.
Steps that make sedimentary rock:
Weathering
Erosion
Deposition
Compaction
Cementation

12. Sedimentary Rocks : Erosion
Weathering is any process that breaks down rocks and creates sediments. There are two forms of weathering, chemical and mechanical (physical).
Erosion is the process by which natural forces move weathered rock and soil from one place to another.

13. Deposition
The process by which the sediment settles out of the water or air carrying it.
Sediment is deposited when the wind or water slows down.
After sediment has been deposited, the process of compaction and/or cementation change the sediment into sedimentary rock.

15. Compaction
As sediments settle they will loosely fit on top of each other.
Over many years, more and more sediment is added.
The bottom layers get compacted by the weight of the layers above them.
Compaction is the process that presses sediments together.

16. Cementation
While compaction is going on, minerals in the rock slowly dissolve and seep into spaces between the compacted sediment.
Cementation is the process in which dissolved minerals crystallize and glue particles of sediment together.

17. Distribution of Rocks in the U.S.

19. The Rock Cycle
The rock cycle is a series of processes on Earth’s surface and inside the planet that slowly change rocks from one kind to another.
Earth’s constructive and destructive forces – including plate tectonics – move rocks through the rock cycle.
There is no beginning or end to the rock cycle.
The rock cycle can follow many different pathways.

20. The Rock Cycle and Plate Tectonics
Plate movements drive the rock cycle by pushing rocks back into the mantle, where they melt and become magma again.
Plate movements also cause folding, faulting, and uplifting of the crust that move rocks through the rock cycle.
Colliding continental plates can squeeze sandstone from the ocean floor resulting in the sandstone being changed to quartzite.
The colliding continents can form mountain ranges or plateaus made of metamorphic rock.

21. Weathering
Any process that breaks rock down into sediments (tiny rock fragments)
There are two types of weathering:
Chemical weathering—rocks are weathered down by chemical and become new compounds.
Ex: Salt water corrosion
Physical/mechanical weathering—breaking rock into small pieces.
Wind, gravity, chemical weathering weakening the base, earthquakes, ____

22. Erosion
Erosion is where natural forces move weathered rock and soil from one place to another.
Erosion occurs by
Gravity
Running water (rivers)
Glaciers
Waves (water)
Wind
Anything moved by erosion is called sediment.

23. Weathering is the actual breaking down of the rock.
Erosion is the carrying away of the rock.

24. Deposition
Deposition—when the erosion stops and deposits (lays down) the sediment.
This happens because the wind or water is dying down/slows down.
Sediments can be deposited on other sediments and form layers of rock.

25. Weathering, Erosion, and Deposition happen on Earth because Gravity pulls everything toward the center of the Earth.
Therefore rocks and other materials want to roll downhill.
The movement of water above and below ground causes most weathering and erosion.
This causes a change in the surface of land and can create underground caves.

26. The Effects of Weathering and Erosion
Changing the shape, size, and texture of landforms.
Mountains, river beds, and beaches change
Landslides
Buildings, statues, and roads wear down.
Soil formation
Pollutants and harmful sediments can be washed into waterways.
Metals rust
Reduces beaches and shorelines.
Forms new landforms by the deposition.

27. Weathering or Erosion?
1. Through rain, older statues being to deteriorate.
2. A landslide carries a truck from the top to the bottom of a hill.
3. Hundreds of people who’ve touched a stalagmite in Mammoth Caves have caused the once sharp, rigid rock to now be smooth as glass.
4. A strong wind storm topples a tall pillar over on it’s side.
5. A strong wind storm blows the fan of a windmill away.
6. A flood picks up many small boulders and carries them down the river.
7. Sand dollars from along the shore line are moved at high tide and left behind at low tide.
8. An owner didn’t leash their dog and it ran out after it’s ball in the ocean. The dog is caught in a rip current and pulled away.
9. A young man is trying to push over an old palm tree on the beach. A huge wave comes up and toppled the tree over on top of the man.
10. The roots of a tree crack a rock apart.
11. An arch shape forms within a mountain.

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32. Water is wet.
Wet—covered or saturated with water.
Water is made of water. Water contains water inside it. All water is touching other water unless the water molecule is by itself.
Looking at water as a whole, since water contains water within it, it is wet.