GLY1000 Assignment Igneous Rocks and Processes
(Note: You can use this form or create your own. Please number your answers. Your drawings can be hand-drawn or created using software if desired. You can take a photo and insert then, or attach them to your submission). Note that I have left this as a Word document, so you can resize the blank spaces to best format your completed worksheet.
1. What is magma, and how does it differ from lava?
2. Describe how and why the rate of cooling is different for magma and lava.
3. Discuss how the rate of cooling influences crystal size.
4. As a logical extension of your previous answers, explain why the crystal size of Granite is distinctly different from Basalt.
5. Hand draw a sample of the rocks below to illustrate the texture of the rock (crystal size).
GRANITE
Phaneritic Texture
BASALT
Aphanitic Texture
6. Granite and Basalt above typify two different textures. Please name four other igneous textures (these are listed in the textbook) and either briefly describe or give a few key words next to each that describes the way it looks. For example, a vesicular texture looks like it once contained bubbles of gas.
7. Igneous rocks can also be classified based on their minerology (what minerals they contain). Please describe the difference between the minerology of Felsic and Mafic rocks.
8. In the table below, provide the name of the texture for the rock listed, whether they cooled rapidly or cooled slowly, are extrusive or intrusive, and the term for the mineral composition.
Name
Use word to best describe the texture
Rapid or Slow Cooling?
Extrusive or Intrusive?
Felsic, Intermediate, or Mafic?
Pumice
Scoria
Rhyolite
Granite
Obsidian
Basalt
Gabbro
Peridotite
Volcanic Breccia
2
Igneous Rocks and Processes Summer 2019
