1. The Rock Cycle

2. Rock Cycle:
A rock is a mixture of minerals, mineraloids, glass or organic matter.
The rocky cycle shows how one rock changes into another.
Rocks are changed by the following:
Weathering Erosion
Compaction Cementation
Melting Cooling

3. Rock Cycle

4. Igneous Rocks
Igneous rock- Occurs when molten material from a volcano or from deep inside Earth cools. Most abundant type of rock on Earth.
obsidian
pumice

5. Igneous Rocks cont.
Great pressure and heat melt the rock to form magma
Also radioactive elements in rock generate thermal energy
Heats rocks
Less dense than surrounding rocks, forced upward and released from volcanoes as lava.
Lava and magma contain Silica
The more silica the more viscous (thick) it is.

6. Metamorphic Rocks
Metamorphic Rock- Rocks that have changed due to temperature and pressure increases or that undergo changes in composition
Metamorphic Rock
Formed from igneous, sedimentary or other metamorphic rock
Changes in appearance, texture, crystal, structure, and or mineral content

7. Metamorphic Rocks cont.
Heat and pressure not enough to melt the rock like igneous
Pressure and heat flatten rocks, exchanges atoms with other minerals
Amount of pressure can determine what rock will form
One rock can change into several different rocks
i.e. shale will change to slate but as more pressure is applied could change into phyllite, schist, and gneiss

8. Metamorphic Rocks
quartzite
hornfels
marble

9. Sedimentary Rock
Sedimentary Rock- Formed when sediments become pressed or cemented together or when sediments precipitate out of solution
Sedimentary Rock
75% of Earth’s Surface
Formed from sediments
Sediments- loose materials such as rock fragments, mineral grains, and bits of plant and animal remains that have undergone weathering and erosion
Minerals dissolved in water are also sediments
Come from already existing rocks that are weathered and eroded

10. Sedimentary Rocks Cont.
Movement of weathered material is called erosion.
Often form layers
Oldest layers are at the bottom
Except when disturbed by some force within the Earth
Compaction
Large sediments cannot be compacted alone by pressure
Cementation occurs when these large sediments are glued together by minerals deposited b/w the sediments by water

11. Sedimentary rocks
conglomerate
coquina
Limestone breccia

12. Uses of Rock Construction Slate Crushed Brick, Facing, Monuments
Pool tables, Roofs
Crushed
Roads, Erosion control, concrete