1. Rocks

2. Igneous Rocks
Intrusive: form when magma cools ___________ inside the Earth.
Extrusive: form when lava cools ___________ on the Earth’s surface.

3. Texture of Igneous rocks
Intrusive igneous rocks:
Cool slowly
Allows time for the minerals to form _________ crystals
Rocks with large crystals have a _____________ texture
Example: granite, gabbro

4. Granite Gabbro

5. Extrusive igneous rocks
Cool _____________
Quick cooling doesn’t allow time for large crystals to form
This produces a ___________ texture
Example: basalt
Extremely rapid cooling cause NO crystals to form
Example: obsidian (volcanic glass)
Sometimes gasses are trapped in cooling magma and form bubbles
Example: pumice ,scoria

6. Basalt Obsidian

7. Pumice Scoria

8. Igneous Rock Structures
Intrusion: underground rock mass made of intrusive rock
Extrusion: surface rock mass of extrusive rock

9. Intrusions Batholith: Laccolith: ____________ intrusion
Large underground mass of rock which may cover hundreds of miles
Laccolith:
Magma flows between rock layers and spreads upward, pushing the rock above into an ___________

16. Sill: Sheet of magma ________________rock layers and hardens
They are always parallel to the ______________ rock layers
Can be thin (few centimeters) or thick (several hundred meters)

17. Dike: Forms when magma forces its way into existing fractures
Once magma hardens it is called a dike
Dikes cut ___________ rock layers (perpendicular to them)

19. Extrusions Volcanic neck: Lava flow: Lava capped-plateau
Solidified central shaft of a volcano
Lava flow:
Erratically shaped mass of extrusive rock
Lava capped-plateau
Lava that spreads over vast area and hardens