"Bounding" through Dunes
Homework 1_Vast Deserts on Mars
Julia Kahmann-Robinson PhD and Marjorie Chan PhD, University of Utah Department of Geology & Geophysics
- Recognize bounding surfaces in Google Earth imagery and their meaning in the geologic record.
- Understand why or why not bounding surfaces are recognized on Mars.
- Make sure you have Google Earth downloaded to your computer to accomplish this exercise. http://www.google.com/earth/download/ge/agree.html
- Students need an understanding of eolian systems, particularly dune formation and sedimentary structures (i.e. bounding surface, planar cross bedding, dunes marching away, toward you etc.) to be successful in this exercise.
Checkerboard Mesa, Zion National Park UT
Open Google Earth (load the free program if necessary) and navigate to:
Navigate to 37°13'30.75"N 112°52'54.13"W and orient the window looking Southwest. See image below* for orientation of your viewing window
Capture your own .jpg and insert your image into a PowerPoint file (see Figure 1* to make sure you have the right orientation).
*Figure 1 in this exercise is not zoomed in or large enough for your PowerPoint slide
In PowerPoint annotate your image with the following:
- Paleocurrent direction- red arrows
- Bounding surfaces- green lines
- Dunes are "marching towards you" – blue triangles
- Dune are "marching away from you"...in any direction – orange triangles
On another slide answer the following questions
- What do the bounding surfaces represent? [changing paleocurrent]
- What created the sinusoid (sine wave) morphology of beds? [Similar to above, changing paleocurrent and how the dunes are coming/going away from you.]
Burns Formation, Meridiani Planum Mars
Insert the following Burns Formation image (Figure 2) into a slide and do the following (Image Source: http://marsrover.nasa.gov/gallery/all/1/p/288/1P153752565ESF37MIP2544L7M1.HTML):
- Follow the same instructions for labeling as followed for Checkerboard Mesa above (answers to the following questions should be given in a separate slide as well).
- What are the main differences between Checkerboard Mesa and the Burns Formation outcrop? (cite at least 3)
- Do you think the Burns Formation was formed in an eolian environment, why or why not?
- In the below photos, what is helpful about the colorized imagery and what can you observe in Image C of Figure 3? Why are some layers "looking different"? [In Image C you are observing graded bedding implying either a changing depositional environment to carry/deposit larger grain sizes, or increasing paleocurrent velocity.]