Spits on Mars
In-Class Activity_Water World
Julia Kahmann-Robinson PhD and Marjorie Chan PhD, University of Utah Department of Geology & Geophysics
- Understand the concept of longshore drift and the geomorphic features it creates/develops.
- Search for and identify sand spits/tombolos on Mars
- Have an Internet connection in classroom.
- Prepare MOLA colorized elevation maps if desired (see Exploration)
Spit Formation in the UK and longshore drift: http://www.youtube.com/watch?v=Fe9YBuK_qEo&feature=endscreen&NR=1
Have students view the following video of Spit Formation in the UK and consider the following questions:
- On the beach, where would the coarsest of grain sizes be deposited (nearest the ocean or nearer the land; proximal/distal)?
- What determines the location of particular grain sizes?
- What governs the growth of a spit?
Using a MOLA colorized elevation map have students do the following (students may come up to the screen and point, or students can annotate a map):
- Mark or point to areas on Mars where spits could be present.
- How did they make their decisions? [Answers can range from finding an area with and open basin, cuspate like features or peninsulas that jet out from the dominant "shoreline" morphology etc.]
- If longshore drift were present in your chosen regions, what direction is the longshore drift heading?[answers vary]
Longshore drift- <a></a>caused by wave and current action. It is the primary method of sediment transport along the beach. The direction of this motion is always parallel to the beach face.
- What do deposits of longshore drift look like in cross-section? [encourage graded bedding and/or swash zone sedimentary structures such as planar cross beds etc.] *Have students hypothesize or perhaps draw a stratigraphic section of sorts and guide them
- What determines the size of grains that are deposited?[High energy can deposit larger grains and low energy smaller grains]
View the following Mars image online of Cape Verde at Victoria Crater on Mars: http://www.nasaimages.org/luna/servlet/view/search/where/Cape+Verde?q=+mars+rover&os=0&pgs=50&sort=Title%252CDate
- Ask students to point out high energy rocks [cross-beds, cliff-forming] and low energy rocks [finer-grained slope forming material]
- While this is not the right depositional environment, the image does illustrate varying energy environments of deposition.