Volcanos

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Assignments

Chernicoff, Volcanos, ch. 4. Audubon Society Field Guide to the Weather, pp. 569-570.

Reminders

McPhee's "Cooling the Lava" DWG has been posted after the fact for review purposes, if you like. The Mars Show is presented every Friday night at 8 p.m. If you can't make this regular evening time then let me know whether you could make it Monday April 13 from 10:00 to 10:45 a.m. For the upcoming optional movie night (date to be announced) we may watch any two movies of geological, meteorological, or planetary interest. I had originally thought of Twister and Dante's Peak, but have now decided to open it up for your nominations. The following movies have been nominated: Twister, Dante's Peak, Jurassic Park, Contact, and Bringing up Baby (starring Cary Grant as a palaeontologist). Email additional nominations to me this week and then next week we'll take a vote to get the top two.

Reading Focus Questions

Read the entire chapter. Study the illustrations. Focus your attention on the vocabulary terms found in the following questions. Be prepared to answer any of these questions should they occur on a quiz or on the final exam.

Note: Some of the terminology for this chapter is covered in chapter 3 on igneous rocks. We are covering chapter 4 before tackling chapter 3 because volcanos are more familiar to most of us than the characteristics of igneous rocks, and I hope that learning about them will heighten your interest in the chapter on igneous rocks (which we will look at next week). So for today just read past the terms about igneous rocks that you don't understand (e.g., felsic, mafic, plutonic, etc.) and don't worry about them, focussing instead upon the terms relating to volcanos themselves.

1.  
2. An active volcano is one that:
   1. erupts almost continuously
   2. is erupting or has erupted recently
   3. erupts at least once every 100 years
   4. is located near a fault

    

3. True or False? Active volcanos are located on all continents except Antarctica.

    

4. True or False? An eruption will be more violent if the gases near the top of the magma body are confined.

    

5. The more viscous a magma is:
   1. the more easily it can flow
   2. the greater its resistance to flow
   3. the higher its temperature has been raised
   4. the thinner it has become

    

6. True or False? Felsic magmas tend to create violent eruptions. (See note above; we'll discuss this more next week)

    

7. True or False? Mafic magmas are more likely to reach the Earth's surface. (See note above)

    

8. True or False? The most common type of lava is basaltic and has a felsic composition. (See note above)

    

9. True or False? Pahoehoe and aa may be produced by the same flow.

    

10. The major difference between aa and pahoehoe is in:
    1. chemical composition
    2. the temperature of the parent magmas
    3. gas content
    4. surface texture

     

11. The easiest way to identify scoria is by its:
    1. chemical composition
    2. extremely light weight
    3. great number of vesicles
    4. smooth, ropy surface

     

12. Thick beds of basaltic lava that cool and shrink may create:
    1. blocks of obsidian
    2. columnar jointing
    3. lava tubes
    4. pahoehoe

     

13. Geologic pillow structures are formed:
    1. as lava is propelled through the air
    2. under water
    3. by expanding gases
    4. by contracting magma

     

14. Pumice:
    1. is a product of basaltic lava
    2. is a product of andesitic lava
    3. has a surface similar to aa
    4. is a product of rhyolitic lava

     

15. True or False? The terms pumice and scoria are synonymous.

     

16. True or False? Volcanic bombs and blocks are both pyroclastics.

     

17. True or False? Cinders are the largest of the tephras.

     

18. True or False? Mount Mazama's Crater Lake is actually a caldera.

     

19. True or False? Tuff is associated with effusive flows.

     

20. Lahars:
    1. are found on the surface of pahoehoe
    2. are also known as nuee ardentes
    3. are liquid tephra
    4. are volcanic mudflows formed from pyroclastics material mixed with water

     

21. True or False? Acidic rain is a common product of volcanic eruptions.

     

22. A steep-walled, bowl-shaped depression surrounding the vent from which volcanic products emanate is a(n): ________________.

     

23. The large depression formed when an unsupported summit of a volcanic cone collapses inward is a(n): ________________.

     

24. True or False? The majority of the world's volcanos surround the Atlantic Ocean.

     

25. The prediction of volcanic eruptions does NOT involve:
    1. the measurement of changes in a volcanos surface temperature
    2. the measurement of a volcano's slope
    3. gauging the pressure on surrounding rocks
    4. monitoring escaping gases

     

26. Most of the volcanos on Mars are of the ________________ type (including Olympus Mons, taller than Everest and nearly the size of Oklahoma).

     

27. ________, one of Jupiter's moons, has active volcanos (including Pele, which has a base as large as Alaska).