Name ________________________________________________________ UA Net ID ____________________ Homework #6 - Due no later than Tuesday, March 22,

Homework6_GEOS170_S16

Name ________________________________________________________ UA Net ID ____________________

Homework #6 – Due no later than Tuesday, March 22, beginning of class. You can also complete this homework in a study group before 3/22 for 2 additional points.

Part I: Hot Spots

1. Explain what a hot spot volcano is in your own words.

2. What is the relationship between hot spots and plate boundaries (see image below)?

3. Two hot spots in the United States are the hot spots that create Hawaii and Yellowstone. Compare and contrast these two hot spots. Would you expect them to erupt in similar ways or not? Explain.

1

Use the map of the Emperor-Hawaiian seamount/island chain when answering the following questions. Note: Numbers beneath island/seamount names are the ages when those rocks cooled (in millions of years).

4. Were the islands of the Emperor – Hawaiian island chain formed by several different hot spots or one hot spot? Explain.

5. How old is the oldest of the seamounts? How old is the youngest island?

6. Hot spot islands form as a plate moves over a hot spot. Draw arrows on the map above to show the direction the Pacific plate has moved in the past (Emperor chain), and the direction it is moving today (Hawaiian chain).

2

7. Has the Pacific plate always been moving in the same direction? How can you tell?

8. At roughly what time in the past did the Pacific plate change its direction of motion? How can you tell?

9. The eight principal islands of Hawaii, shown in the dark blue box (zoomed in), are all above sea level. Most of the remaining islands of the Emperor-Hawaiian island chain are now seamounts, meaning they are no longer above sea level. Why do you think the younger Hawaiian Islands are above sea level while the oldest (Emperor seamounts) are all under water?

10. What type(s) of eruption(s) are common today on the island of Kauai (oldest of the principal Hawaiian Islands)? What type(s) of eruption(s) are common today on the big island of Hawaii (youngest of the principal Hawaiian islands)? Explain your answers.

3

Part II: Mass Wasting (Landslides)

Mass wasting is defined as the downslope movement of material under the influence of gravity. If a slope is very steep, gravity alone can cause material to move downslope. However, other factors can influence mass wasting. Watch the short video at the web address below and answer questions 1-4. If you do not have access to a computer, the video will be playing in study groups:

http://www.youtube.com/watch?v=HiNwmj5ALZs

11. What is one factor besides gravity that can trigger a mass wasting event (i.e., landslide)? Explain why this factor is important.

12. Name a place on Earth that you predict would be prone to landslides, and discuss why you chose that location.

13. Name a place on Earth that you predict would not be prone to landslides, and discuss why you chose that location.

14. In terms of geologic time, are mass wasting events fast or slow? Explain.

4

Watch the short video at the web address below and answer questions 15-17. If you do not have access to a computer, the video will be playing in study groups.

http://www.youtube.com/watch?v=aajUXQmec-Q&feature=related

15. What is different about this mass wasting event as compared to the landslides discussed in the previous video? Explain.

16. Which type of mass wasting event do you think is more common in a desert – a rock fall like the one in this video, or a landslide like the ones explained in the previous video? Explain.

17. This event did not involve excess precipitation. Can you think of something (an event or situation) that could cause dry, solid rock to come loose from a slope? Describe it.

18. In general, do you think dry climates (i.e., deserts) or wet climates experience more mass wasting events? Explain.

5

Look at the block diagrams below. They show how material on a slope experiences two components of gravity – one acting parallel to the slope (labeled gs) and one acting perpendicular to the slope (labeled gp). Refer to this diagram to answer question 19:

19. In which of the above diagrams is a mass wasting event more likely to occur, simply based on the influence of gravity? Explain.

20. Can you think of a situation that would cause a slope to become steeper, thereby allowing for mass wasting events? Where might this happen? Explain.

6