Dept. Logo

Name = ______________________
Geology 333 - Homework #4 (Plate Tectonics on Earth and Other Planets, Meteorite Impact Craters)
Available Monday, Feb. 27; Answers are due by 10 AM on Wednesday, March 1.
(10 total points)

Instructions: Follow the instructions in this exercise and answer all questions on a separate sheet of paper or directly on the question sheet, which you must print out. To access the Web sites listed below, click on the links given in this exercise. NOTE: Clicking a link opens the page in a new window. The purpose of this exercise is to explore the topics of the driving mechanism of plate tectonics, plate tectonics on other celestial bodies in our solar system, and meteorite impact craters.

Part I - Plate Tectonics on Earth

1) Go to a USGS on-line publication This Dynamic Earth: The Story of Plate Tectonics (in the subsection Some Unanswered Questions):

http://pubs.usgs.gov/publications/text/unanswered.html

Read the first section What Drives the Plates? and answer the questions below.

(a) The motion associated with the tectonic plates is called convective flow. What general feature drives convective flow in the moving tectonic plates? (0.33 pts)

 

(b) What are two sources of the general feature that drives convective flow in the moving tectonic plates? (0.67 pts)

 

(c) Briefly describe the most recent idea of geologists about the major specific mechanism that drives the moving tectonic plates? (0.5 pts)

 

Part II - Extraterrestrial Plate Tectonics

2) If you were studying photographs of another planet, list at least 3 different features would you look for to determine whether or not the planet is or has been tectonically active? (1.5 pts)

 

 

 

 

 

3) Go to NASA's Welcome to the Planets Web site at http://pds.jpl.nasa.gov/planets/

(a) Click on the image of Venus to examine a variety of photographs of various features of Venus. The direct URL is: http://pds.jpl.nasa.gov/planets/choices/venus1.htm.

You can click on individual photographs to get an expanded view accompanied by an explanation.

Do any of the photographs provide evidence that Venus has ever been tectonically active? (0.5 pts)

If yes, then list at least one feature that is evidence that Venus has been tectonically active at some point. If no, then explain why not. (0.5 pts)


(b) Return to the Welcome to the Planets home page at http://pds.jpl.nasa.gov/planets/ Now click on the image of Mars to examine a variety of photographs of various features of Mars. The direct URL is: http://pds.jpl.nasa.gov/planets/choices/mars1.htm.

You can click on individual photographs to get an expanded view accompanied by an explanation.

Do any of the photographs provide evidence that Mars has ever been tectonically active? (0.5 pts)

If yes, then list at least one feature that is evidence that Mars has been tectonically active at some point. If no, then explain why not. (0.5 pts)


(c) Return to the Welcome to the Planets home page at http://pds.jpl.nasa.gov/planets/ Now click on the image of Jupiter to examine a variety of photographs of various features of Jupiter. Navigate to the 3rd and 4th screen of images (by pressing the 'down arrow' button) to view photographs of Io, Europa, and Ganymede, three of Jupiter's moons. The direct URLs are

http://pds.jpl.nasa.gov/planets/choices/jupiter3.htm
http://pds.jpl.nasa.gov/planets/choices/jupiter4.htm

Do any of the photographs provide evidence that either Io, Europa, or Ganymede has ever been tectonically active? (0.5 pts)

If yes, then list at least one feature that is evidence that Io, Europa, or Ganymede has been tectonically active at some point. If no, then explain why not. (0.5 pts)


4) Return to the USGS on-line publication This Dynamic Earth: The Story of Plate Tectonics (in the subsection Some Unanswered Questions):

http://pubs.usgs.gov/publications/text/unanswered.html.

Read the second section Extraterrestrial Plate Tectonics? and answer the questions below.

(a) Discuss the status of plate tectonics on Mars. Specifically, you should address whether or not there is any evidence plate tectonics has occurred on Mars and if so, when. (0.5 pts)

 

(b) Discuss the status of plate tectonics on Venus. Specifically, you should address whether or not there is any evidence plate tectonics has occurred on Venus and if so, when. (0.5 pts)

 

(c) Discuss the status of plate tectonics on Io and Ganymede (moons of Jupiter). Specifically, you should address whether or not there is any evidence plate tectonics has occurred on Io and Ganymede and if so, when. (0.5 pts)

 

(d) List two factors that control whether or not a planet is able to sustain plate tectonic activity. (0.5 pts)

 

Part III - Meteorite Impact Craters

5) Both our Moon and planet Earth are thought to have formed about 4.6 billion years ago and both are thought to have been bombarded with many meteorites during the first 1 billion years of their history. However, the surface of our Moon contains many craters produced by the collisions of those meteorites whereas the surface of Earth shows relatively few craters from meteorite impacts. For your information, you can see photos of meteorite impact craters on Earth (as well as lots of other related information) at the following Web sites:

http://neo.jpl.nasa.gov/images/ (under Crater/Impact Photos)

http://www.lpi.usra.edu/publications/slidesets/craters/crater_index.shtml (scroll to the bottom of the screen).

You can see photos of the Moon, including some meteorite impact craters, at

http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-moon.html

(a) Explain why there are relatively few craters from meteorite impacts in Earth's oceanic crust compared to the surface of our Moon. (HINT: This explanation should involve plate tectonics. Be specific in your explanation.) (1 pt)

 

 

 

(b) Explain why there are relatively few craters from meteorite impacts in Earth's continental crust compared to the surface of our Moon. (HINT: This explanation does not involve plate tectonics but rather a major difference in the environment surrounding Earth's continental crust compared to the environment surrounding the surface of the Moon.) (1 pt)