1. Rockin’ Science
Rocks and Rock Cycle

2. What is a rock?
Mixture of minerals, volcanic glass, organic or other materials.
There are three types of rocks:
Igneous
Metamorphic
Sedimentary

3. Igneous Rocks formed when hot magma cools and hardens.
Magma vs. lava –
Magma is hot, melted rock material beneath Earth’s surface
Lava is magma that reaches the Earth’s surface and flows from volcanoes

5. Two Types of Igneous Rocks
Intrusive – generally contain large crystals, and forms when magma cools slowly beneath Earth’s surface.
Extrusive – fine-grained, and forms when magma cools quickly at or near Earth’s surface

7. Further Classification
Another way to identify igneous rocks is by the magma from which they form
Basaltic Rocks – igneous rocks that are dense and dark in color. They form from magma that is rich in iron and magnesium, but poor in silica.

8. Granitic Rocks
Igneous rocks that have a lower density than basaltic rocks, and are light in color. Granitic magma is thick, stiff and contains lots of silica.

9. Andesitic Rocks
Igneous rocks that have a mineral composition between basaltic and granitic rocks

10. Mighty Morphin’ Rocks
Metamorphic Rocks

11. Formation
Metamorphic rocks form when heat, pressure, or fluids act on igneous, sedimentary, or other metamorphic rocks.
The heat and pressure can change the rocks form, composition, or both.

12. Heat and Pressure…
Rocks beneath Earth’s surface are under great pressure from the layers above them.
Temperature also increases with depth.
The amount of heat and pressure along with the composition of the rock determines what the metamorphic rock will look like.

13. Type of Rock Before
Type of Rock After (metamorphic)
Granite/Igneous
Gneiss
Sandstone/
Sedimentary
Quartzite
Limestone/
Marble

14. Hot Fluids
In the presence of hot, water-rich fluids, solid rock can change in mineral composition without having to melt.

15. Classifying Metamorphic Rocks
Foliated rocks - when mineral grains flatten and line up in parallel layers
Nonfoliated rocks - when mineral grains grow and rearrange but do not form layers.

16. Examples of Foliated Rocks…

17. Examples of Nonfoliated Rocks…

18. Sedimentary Rocks
And the Rock Cycle

19. Settlement - Sediment
Sediments are loose rock fragments, mineral grains, and shell that have been moved by wind, water, ice, or gravity.
Sedimentary rocks form when sediments are pressed and cemented together.
They often form layers. The oldest layer of rock is on the bottom.

21. Classification
Detrital
Chemical
Organic

22. Detrital Made of grains of minerals or other rocks.
Other minerals dissolved in water act to cement particles together, and the weight of the sediment above them also squeezes or compacts the layers into rock.

23. Detrital Rocks

24. Chemical Rocks
Form when mineral-rich water from geysers, hot springs, or salty lakes evaporate.
Limestone, rock salt, dolostone

25. Organic Rocks
Rocks made of once living things
Chalk, Coal

26. Rock Cycle