1. Igneous Metamorphic Sedimentary
Rocks
Igneous
Metamorphic
Sedimentary

2. What is a Rock? A rock is composed of minerals
Can be made of organic material
Solid material that forms Earth’s hard surface.

3. Igneous Rock

4. Igneous Rock
Rock that crystallizes from cooling of magma (inside Earth) or lava (on/outside surface of Earth)
Characterized two ways – INtrusive or EXtrusive

5. Intrusive Igneous Rock
Crystallizes inside of Earth from magma
Magma cools slowly (because of the blanket of the Earth’s layers)

6. Intrusive Igneous Rock (continued)
Devils Tower, Wyoming
Cooling slowly = large interlocking crystals (usually two or more colors)
Large crystals = coarse-grained texture

7. Igneous Intrusive Rock Samples
Granite
Note 3 minerals = mica (black)
quartz (smoky)
feldspar (pink)

8. Extrusive Igneous Rock
Crystallizes outside of Earth from lava – mostly from volcanic activity
Lava cools quickly
Cooling quickly = tiny or no mineral grains (usually one drab color)

9. Extrusive Igneous Rocks (Continued)
Tiny or no mineral grains = fine-grained texture
EXTRA : Sometimes has pores or holes from trapped gases

10. Extrusive Igneous Rock Samples
Basalt (seafloor)
Notice the drab color
Notice the holes or pores
Pumice
Notice the very smooth texture
Obsidian
(volcanic glass)

11. Mafic vs Felsic
Mafic igneous rocks - dark in color and have a high density due to high quantities of heavy elements (magnesium, iron, calcium and sodium)
basalt (extrusive) and gabbro (intrusive).
Felsic igneous rocks – light in color and have a lower density due to high quantities of lighter elements (silicon, oxygen, aluminum, sodium and potassium)
Pumice (extrusive) and granite (intrusive)

12. Sedimentary Rock
How does Sedimentary Rock form?

13. #1 #2 #4 #3

14. Sedimentary Rock
Formed at surface of Earth (in lakes, oceans, rivers) in thin or thick layers (strata)
Layering is referred to as stratification
Formed from Cementation & Compaction of sediments or Evaporation/Precipitation
Only rock type to contain fossils
Characterized two ways – clastic or non-clastic

15. Clastic Sedimentary Rock
Mineral grains (sediments/fragments) are compacted and cemented together.
Example – sand compacted and cemented = sandstone
Example – mud/clay compacted and cemented = shale
Example – pebbles, sand and mud compacted and cemented = conglomerate

16. Clastic Sedimentary Rock Samples
shale field
sandstone

17. Non-clastic Sedimentary Rock
Two types – Organic Non-clastic or Chemical Non-clastic
Organic – made from once living things – plants (coal) or animal life (fossil rich limestone - coquina)
Chemical – made from evaporation (gypsum) or precipitation – (CaCO3 – chemical limestone)

18. Non-clastic Sedimentary Rock Samples
Coal - organic
Chemical limestone
Fossil rich limestone - organic
Gypsum - chemical

19. Sedimentary Features
Ripple Marks – left by water or wind in sand, mud, etc. – can be preserved as a rock feature

20. Sedimentary Features
Mud cracks in today’s puddles can be preserved as rock millions of years from now

21. Sedimentary Features
Cross bedding – formed in old sand dunes or on off-shore sand bars

22. Metamorphic Rock
How is metamorphic rock formed?

23. Metamorphic Rock
Formed deep inside the Earth from intense heat and pressure
Any rock type can be changed by metamorphism – depends on how much heat, pressure and original rock type to determine the outcome
No melting involved – solid state process (more like softening)
Hardest of three types of rock
Characterized two ways – foliated or non-foliated

24. Foliated Metamorphic Rock
Banding (stripes) or cleavage (flaky) is present
Always a change structure and texture of original rock and sometimes a change in the composition.
When composition changes – most often a semi to precious gem can be formed.

25. Foliated Metamorphic Rock Samples
Gneiss (Previously granite)
schist

26. Non-foliated Metamorphic Rock
NO Banding and/or NO cleavage
Change in structure and texture of original rock
Possible change in composition.

27. Non-foliated Metamorphic Rock Samples
Quartzite
(previously sandstone)
Marble
(previously limestone)