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?
- If longshore drifts were present in your chosen regions, what direction is the longshore drift heading?
ExplainLongshore drift- 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.
This USGS website gives a description of longshore motion parallel to the beach face.
Here is another short movie on longshore drift, but it does not explain that the return flow back to the ocean takes a pathway directly perpendicular to the shoreface (the shortest distance back under the influence of gravity).
- What do deposits of longshore drift look like in cross-section? *Have students hypothesize or perhaps draw a stratigraphic section of sorts and guide them
- What determines the size of grains that are deposited?
View the following Mars image online of Cape Verde at Victoria Crater on Mars:
- Ask students to point out high energy rocks and low energy rocks.
- Note to teacher to be shared with students: While this is not the right depositional environment, the image does illustrate varying energy environments of deposition.
- While this is not the right depositional environment, the image does illustrate varying energy environments of deposition.