2005 Salt Lake City Annual Meeting (October 16–19, 2005)

Paper No. 7
Presentation Time: 9:30 AM


DAVIS, Jena1, PLUMMER, Mitchell2, MATTSON, Earl2 and MCCANDLESS, Melanie3, (1)2214 Rendezvous, Idaho Falls, ID 83402, (2)P.O. Box 1625, Idaho Falls, ID 83415-2107, (3)Geology, Tufts University, 46 Hemlock Hill Rd, Carlisle, MA 01741, Dav01031@byui.edu

Glaciers are a dramatic display of nature's forces in the mountains and are increasingly mentioned as a notable indicator of global warming, as glaciers in many parts of the world appear to be shrinking at alarming rates. To illustrate not only how glaciers help to carve mountains but also how they work and how they respond to climate we have developed an inquiry-based learning unit on glaciers that includes three relatively new hands-on and/or computer animations of glaciers and how they work. The first of these is an extension of a lesson already available on the web (see http://www.uoguelph.ca/ ~geology/glacial/ice.html) in which students simulate a glacier by making plaster flow in a open channel. The principal goal of this exercise is to illustrate how plastic flow acts to produce a variety of common glacier features, like crevasses and ogives. In our work, we demonstrate a simple means of constructing a small mountain range for the plaster flow lesson, to illustrate additional glacial features, such as converging glacier flow and medial moraines. One of the shortcomings of such a presentation however, is that it gives a somewhat misleading sense of glacier mechanics. In a second demonstration, we therefore focus on the mass balance of glaciers, how and why they respond to climate change and how they can reach a steady-state condition. In addition to introductory material describing the interesting idea of a dynamic, yet unchanging system, this includes a hands-on demonstration of the steady state process in which students are the accumulators and ablators of a mountain basin and “ice” blocks are the flowing ice. By changing the rates at which students add or remove ice blocks from their position in the valley, we illustrate how the ice mass can reach steady state and how responds to climate change. Finally, we relate the concepts presented in the classroom to research on past and present glaciers using a series of animations of numerically simulated glaciers using a 2-D glacier model that simulates the advance and recession of glaciers to climate change. Simulations include growth and recession of last glacial maximum glaciers in the Tetons and the Sierra Nevada and simulations illustrating advance or recession of modern glaciers in the Tetons and in the Mount Saint Helens crater