"Bounding" through Dunes
Figure 1-Google Earth image capture of Checkerboard Mesa, Utah.
Provenance: Google Earth
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Homework 1_Vast Deserts on Mars
Julia Kahmann-Robinson PhD and Marjorie Chan PhD, University of Utah Department of Geology & Geophysics
Purpose
- 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.
Preparation
- Make sure you have Google Earth downloaded to your computer to accomplish this exercise. https://www.google.com/earth/versions/
- 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.
Directions/Questions
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):
Figure 2 Left Panoramic Camera Non-linearized Sub-frame EDR acquired on Sol 288 of Opportunity's mission to Meridiani Planum at approximately 13:10:16 Mars local solar time, camera commanded to use Filter 7 (432 nm). NASA/JPL/Cornell
Provenance: NASA/JPL/Cornell
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- 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.]
Figure 3 Burns Formation: Contacts between stratigraphic units of the Burns formation as obtained by the Pancam at Burns cliff, Endurance crater. (a) Burns formation
at eastern end of Burns cliff. The three informal subdivisions (lower, middle, and upper units) of the formation are visible, as described in Fig. 4.
Because of its broad coverage, the scale varies significantly across area of image. This image is an approximate true-color composite mosaic
generated from images acquired on sol 278, sequence P2440, using Pancam’s 750, 530, and 430 nm filters. (b) Close-up of Wellington contact and
Burns lower unit strata. Note thick lamination of cross-bedding below contact, which contrasts with fine lamination above. Scale of cross-bedding
provided by bar in (a), and by visible concretions (small black dots) which are up to 3–5 mm in diameter. Grayscale bsuper-resolution imageQ using
Pancam’s 430 nm filter on sol 288. (c) Close-up of Burns middle unit/upper unit transition and Whatanga contact. Contact is characterized by an
upward gradation from light to dark tone in upper part of middle unit, followed by an abrupt shift to a much lighter tone which defines the contact.
Grayscale bsuper-resolution imageQ using Pancam’s 430 nm filter on sol 289.
Provenance: Grotzinger, J.P. et al., 2005. Stratigraphy and sedimentology of a dry to wet eolian depositional system, Burns formation, Meridiani Planum, Mars. Earth & Planetary Science Letters, v. 240, p.11-72
Reuse: This item is offered under a Creative Commons Attribution-NonCommercial-ShareAlike license http://creativecommons.org/licenses/by-nc-sa/3.0/ You may reuse this item for non-commercial purposes as long as you provide attribution and offer any derivative works under a similar license.
Turn your .ppt presentation/slides into your instructor.