1. IGNEOUS ROCKS

2. 14.2 Types of pyroclastics (tephra)- material that explodes
out of a volcano.
Volcanic ash- between 0.25 and 2mm in diameter
Lava Flow – Magma that erupts onto Earths Surface.
Lahar- Pyroclastic mudflow/landslide.

3. Volcanic Gases- water vapor (steam), carbon dioxide and sulfur gas.
Pyroclastic Flow - flows are fast-moving currents
of hot gas and rock
Volcanic Gases- water vapor (steam), carbon dioxide
and sulfur gas.
Volcanic bombs- aerodynamic tephra

4. Obj.:14.3 IGNEOUS ROCKS Igneous rocks are formed from molten material.
- The term igneous is derived from Latin term meaning “from FIRE”!!

6. ENVIRONMENT IGNEOUS ROCKS
A. Extrusive igneous rocks are formed when molten
rock cools above ground. Usually they are formed
after the material has been erupted by a volcano.
This molten material
cools quickly.
No crystals are visible
to the eye.

7. Intrusive igneous rocks are formed when
molten rock cools below ground.
These rocks cool
very slowly.
There is lots of
time for visible
crystals to grow

8. Cools slowly Cools quickly Cools above ground Cools below ground
EXTRUSIVE
INTRUSIVE
Cools slowly
Cools quickly
Cools above ground
Cools below ground
No visible crystals
Visible crystals

9. Coarse: TEXTURE IGNEOUS ROCKS
INTRUSIVE igneous rock composed of large mineral grains.
GRANITE

10. Fine: TEXTURE IGNEOUS ROCKS
EXTRUSIVE igneous rock composed of fine-grained minerals.
BASALT

11. Glassy: TEXTURE IGNEOUS ROCKS
HIGHLY VISCOUS, silica-rich magma cools rapidly, no crystals.
OBSIDIAN

12. Vesicular: TEXTURE IGNEOUS ROCKS
HIGHLY VISCOUS, large amount of dissolved gases, rock full of holes.
PUMICE

13. Mafic: COMPOSITION IGNEOUS ROCKS Low silica Rich in Iron and Magnesium
DARK COLOR.
BASALT

14. IGNEOUS ROCKS
COMPOSITION
Felsic:
High silica
LIGHT COLOR.
RHYOLITE

15. Igneous Rock Structures
Intrusions vs. Extrusions:
- Form Underground
- Form on the surface of the Earth

16. STOP
Rock Mini-Lab

17. USE your obj. notes for help
SCIENCE TIP 3/17/11
USE your obj. notes for help
What are the three ways we classify Ign. Rocks?
Explain Extrusive vs. Intrusive
Give two examples of texture of an Ign. Rock.
What is Mafic?
What is Felsic?

19. Batholiths: INTRUSIONS IGNEOUS ROCKS
At least 100 km2 of surface exposure.
Means “Deep Rock”
Sierra Nevada Mountains

21. Laccoliths: INTRUSIONS IGNEOUS ROCKS
Flat-bottom intrusion that pushes over-lying rock layers into an arc.
Means “Lake of Rock”
Black Hills
South Dakota

23. Stocks: INTRUSIONS IGNEOUS ROCKS
Like a Batholith, but covers less than 100 km2.
Devils Tower
Wyoming

25. Dikes: INTRUSIONS IGNEOUS ROCKS
Igneous intrusion that cuts across rock layers.
Black Canyon
Colorado

27. Sills: INTRUSIONS IGNEOUS ROCKS
Hardened magma formed between parallel layers of rock.
Salisbary Crags
Scotland

29. Volcanic Necks: EXTRUSIONS IGNEOUS ROCKS
Solidified central neck of a volcano.
Shiprock
New Mexico