Mapping a local Dune Field, and estimating paleowind speed and direction
Donald T. Rodbell
This activity has benefited from input from faculty educators beyond the author through a review and suggestion process.
This review took place as a part of a faculty professional development workshop where groups of faculty reviewed each others' activities and offered feedback and ideas for improvements. To learn more about the process On the Cutting Edge uses for activity review, see http://serc.carleton.edu/NAGTWorkshops/review.html.
This page first made public: Apr 18, 2008
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We visit the Pinebush dune field in eastern New York State (20 minutes from campus). Students map one large parabolic dune, and collect sample of dune sand. In the lab, students map the dune field from aerial photographs and a DEM, measure the grain size distribution of their samples, and estimate paleo-wind speed and direction
Undergraduate geomorphology course
Skills and concepts that students must have mastered
use of a brunton compass
How the activity is situated in the course
this lab is conduted just after we spend about 1.5 weeks in lecture on eolian process and landforms
Content/concepts goals for this activity
Students use data they collected in the field and lab to address a paleoclimatic question: how different was wind speed and direction (relative to modern values) when a large body of sand was deposited in eastern NY State.
Higher order thinking skills goals for this activity
The initial reaction of students is that it must have been really windy, and very different from today! I play this up a bit. Invariably, when students do some calculations to estimate possible paleowind speeds and compare these with modern values, they find that there is plenty of wind today to move the dunes. Students must then decide what was really different when the dunes were deposited (answer: the sudden draining of Glacial Lake Albany, and the exposure of delatic and shoreline sands in the mouth of the Mohawk Valley.
Other skills goals for this activity
oral and written reports
Description of the activity/assignment
Students map one large hairpin parabolic dune in the Pinebush Preserve. They also profile the slopes on both proximal and distal sides of the dune. As a group, we take an ~ 2m long core of the dune sand to sample the sand beneath the soil profile. In the lab, students measure the particle size distribution of their sand samples, map the whole dune field from aerial photographs and a DEM, and estimate paleo-wind speed and direction. They then compare these data with modern wind data (available from the web) to answer the question of .just how different conditions were when the dune field was deposited
Uses online and/or real-time data
Addresses student fear of quantitative aspect and/or inadequate quantitative skills
Uses geomorphology to solve problems in other fields
Determining whether students have met the goals
quality of lab reports, ability to select a logical parameter of their grain size data to use in the calculations of past wind velocity, quality of their dune maps, and for the students who present their labs orally, the quality of these presentations
More information about assessment tools and techniques.
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