“Types of Rocks” NotesWhat is a Rock?

1. A rock is a NATURALLY OCCURING SOLID MIXTURE of one or more MINERALS and “ORGANIC” matter.

2. Rocks go through a CYCLE meaning they are constantly CHANGING into DIFFERENT forms.

3. How are the types of rocks classified? EACH TYPE OF ROCK CAN BE DIVIDED FURTHER AND CLASSIFIED BASED ON THE DIFFERENT WAYS IN WHICH THE ROCK FORMS.

4. What are two important criteria that scientists use to study rocks in detail?

A) COMPOSITION-- is the chemical make-up (or combination of substances that are contained in a rock). *Composition also determines the “color” of the rock.

B) TEXTURE -- is the size, shape, & position of the rock’s grains. It’s what determines the “QUALITY” of the rock (fine grained, medium grained & coarse grained).

Igneous Rocks : (FIRE ROCKS!!)

5. “Ignis” means FIRE. Igneous rocks are formed from the MELTING and SOLIDIFICATION of magma. Two places where igneous rocks form are: VOLCANOES & RIFTS/RIDGES.

6. Igneous Rocks are made either:

a) UNDERGROUND (intrusive; melted rock called magma cools slowly and solidifies.)

b) ABOVE GROUND (extrusive; volcanoes erupt bringing magma to the surface where it

is called lava. The lava cools quickly and becomes igneous rock.)

Sedimentary Rocks: (SANDWICH ROCKS!!)

9. There are FOUR main processes involved: (*these processes can take thousands to millions of years)

7. What determines Crystal size? Answer: COOLING TIME

Long cooling time produces LARGE crystals. Short cooling time produces SMALL crystals.

8. What’s the Difference between Extrusive & Intrusive Rocks?

a) EXTRUSIVE form on or near the surface making the smaller crystals. *Texture is glassy & fine grained

b) INTRUSIVE form below the surface making the larger crystals. *Texture is rough and very coarse grained

List four examples of Igneous Rocks below:

a. GRANITE b. SCORIA

c. PUMICE d. OBSIDIAN

a. EROSION - after “weathering” occurs, the forces of running water, wind, or ice loosen and carry away fragments of rocks.

b. DEPOSITION - sediments settle out of the water or wind carry them and settle at the bottom of lakes or streams..

c. COMPACTING - process that presses sediments together. Thick layers of sediments build over time weighing down the layers and compacting them.

d. CEMENTATION -.dissolved minerals seep into spaces between particles & crystallize as they harden.

List five examples of sedimentary rocks below:

a.SANDSTONE b.SHALE c.LIMESTONE

d.CONGLOMERATE e.ROCK SALT

*SHALE is the most common form of sedimentary rock. Covers 3/4 of Earth’s surface!

Metamorphic Rocks: (CHANGING ROCKS!!!!)

10. Metamorphic rocks are rocks that have MORPHED or CHANGED INTO another type of rock. The word metamorphic means “CHANGED FORM”.

11. ( True? / or False?) Metamorphic rocks were once igneous and sedimentary rocks.

erate

12. They are formed from extreme HEAT and tons of PRESSURE.

13. “Foliated” metamorphic rocks contain minerals that have been aligned by PRESSURE and almost look like pages in a book. *visible bands

a. Examples include: SCHIST and GNEISS.

14. “Non-foliated” metamorphic rocks do not have DISTINCTIVE LAYERS and are made of ONLY JUST A FEW minerals

a. Examples include: QUARTZITE and MARBLE.