Volcanism

 

Terms to learn:

viscosity              basaltic magma                 silicic magma         pahoehoe
Aa                            pyroclastics-tephra       shield volcano       composite volcano
cindercone         volcanic dome                   caldera                      crater
flood basalts      pillow basalts                     lahar                          nuee ardente

 

Topic outline:

1. Factors affecting nature of volcanic eruption –viscosity
   1. Amount of dissolved gases
   2. Temperature
   3. Silica content
2. Materials extruded during volcanic eruptions
   1. Lava types
   2. Gases
   3. Pyroclastic material (tephra)
3. Types of Volcanoes

 

4. Other volcanic occurrences
5. 1. volcanic domes
   2. Caldera vs. craters
   3. Flood Basalts
      1. columnar jointing
   4. Submarine eruptions – pillow basalts
6. Volcanism and Plate Tectonics
   1. Distribution of volcanic activity
   2. 1. spreading centers
      2. subduction zones
      3. intraplate
7. Volcanic hazards and benefits
   1. primary and secondary hazards
   2. benefits

 

Interesting places to visit:

Great interactive page: http://www.learner.org/exhibits/volcanoes/

 

Lots of great info: http://www.cotf.edu/ete/modules/volcanoes/volcano.html

 

Volcanoes links page: http://www.volcanoes.com/webdocs/websitelinks.html

 

When you are finished with this topic, you should be able to answer these questions:

1.       What three factors determine the nature of a volcanic eruption?

2.       What do pillow lavas indicate about the environment of volcanism?

3.       Why are extrusive rocks fine-grained?

4.       Why do shield volcanoes have such low slopes?

5.       What accounts for the differences between pahoehoe and aa lava flows?

6.       Why do composite volcanoes occur near convergent plate boundaries?

7.       Explain how Crater Lake formed.

7.       Explain how Crater Lake formed.%MCEPASTEBIN%