1. Rock Cycle
How do rocks form?

2. Chapter 4:Rocks: Mineral Mixtures
Section 1: The Rock Cycle
Section 2: Igneous Rock
Section 3: Sedimentary Rock
Section 4: Metamorphic Rock

3. Rock Cycle A rock is a naturally occurring solid mixture of
one or more minerals.

4. Weathering, Erosion, and Deposition
Weathering is the breaking down or dissolving of rocks and minerals on the Earth’s surface.
Water, ice, acids, salt, plants, animals, and changes in temperature are all agents of weathering.

5. Education National Geographic on Weathering

6. Erosion
When water, wind, ice, or gravity move sediments over the Earth’s surface, this is called erosion.

7. Deposition: Deposition is when sediments stops moving and is deposited.

8. ROCK CYCLE

9. Rock Cycle

10. Rock Cycle

11. Igneous Rock

12. Igneous Rock Igneous rock is formed from lava or magma.
Magma is hot, melted rock inside the Earth. (1300 to degrees Fahrenheit
or 700 to 1,250 degrees Celsius)
Lava is magma that has erupted from a volcano.

13. 3 Ways that Magma Forms 1. Increase in temperature
2. Decrease in Pressure
3. Addition of Fluids

14. Classification of Igneous Rock
1. Composition
2. Texture

15. Classification of Igneous Rock: Composition
Felsic Rock
Elements – sodium, potassium, and aluminum
Most felsic rocks are light color
e.g. granite, rhyolite
Mafic Rock
Elements – iron, calcium, and magnesium
Most mafic igneous rocks are dark colored.
e.g. basalt and gabbro

16. How are basalt and gabbro different
For more in formation, read this article to see why they are different.

17. Classification of Igneous Rock: Texture
The texture depends on the size of grains in the rock.
The texture of igneous rocks depends on fast the magma cools.
Intrusive Igneous Rock Extrusive I gneous Rock

18. Intrusive verses Extrusive
Intrusive – inside Earth’s surface
Extrusive- Outside Earth’s surface
The magma cools slowly below the Earth’s surface.
Magma is called lava when it reaches the Earth’s surface. Extrusive igneous rock forms when lava cools, which is quicker on the surface of the Earth.

19. Rock Cycle

20. Sedimentary Rock
Sedimentary is formed by compaction and/or cementation.
When new layers sand, dirt, mud, and pebbles are deposited on top of older layers, the weight causes the grains to squish together tightly. This is compaction.
Cementation happens when the grains stick together like the cement walkways outside this building.
Go to or
for more information.

21. Strata and Stratification
Sedimentary rocks are formed in layers. The formal term for layers is strata (or stratum for short).
Stratification means the act of making strata or layers.
Go to for more information.

22. Rock Cycle

23. Metamorphic Rock
Metamorphic rock forms when the chemical composition of a rock changes because of heat and pressure.

24. Rock Cycle Interactive Activity
Go to this web site. Try it out.

25. Rocks I hope you have a better understanding of the rock cycle.
Powerpoint created by Sallie Muckenfuss Salazar