Coastal Features Around Yellowstone Lake

Newswise — On a recent family trip to Yellowstone Park, University of Arkansas geologist Stephen Boss noted that parts of the shoreline on Yellowstone Lake sport features more commonly seen on coastal areas. With subsequent research and historical photos, Boss has shown that the lake's shoreline has changed dramatically over the past 50 years.

Studying the coastal processes of this sparsely developed lake could provide insight into the natural processes that shape coastal shorelines and assist the National Park Service in developing long-term management plans to preserve the pristine lake shoreline and the abundant archaeological sites found there.

Boss and Barbara Pickup, graduate student in the environmental dynamics program, reported their findings at the Geological Society of America meeting in Seattle.

Yellowstone Lake is the largest lake at its altitude in the world, and formed in an enormous crater following an extraordinarily violent series of volcanic eruptions. Geologists call such craters "calderas," and part of the Yellowstone Caldera later filled with melted glacier water to form Yellowstone Lake. Such lakes typically have steep slopes that continue under water and rapidly become very deep. However, on a family trip to Yellowstone Lake this summer Boss, who studies coastal processes of shorelines, noted that parts of the lake have landforms found in coastal areas, including sand bars, lagoons and spits. Upon returning to work, Boss began looking for any research on the lake's shoreline.

"No one has examined the details of shoreline processes that are going on there right now," Boss said.

Boss and Pickup ordered aerial photographs of Yellowstone Lake from the U.S. Geological Survey Data Center in Sioux Falls, S.D. that date back to 1954. They focused in particular on West Thumb, located in the northwest part of the lake. They are in the process of entering the photographs into state-of-the-art Geographic Information Systems (GIS) software to analyze shoreline changes. An overlay of images from 1994 and 2002 shows visible differences in the shoreline in only eight years.

"Through time, you can see the shoreline change," said Pickup.

Although sandbars, spits and lagoons traditionally are associated with marine coastal ecosystems, large lakes, such as the Great Lakes, also form such features through wave action and sediment transport. Yellowstone Lake differs from the Great Lakes and the coast because it is an alpine, high altitude lake and because it has very little development on its shoreline.

"We're looking at physical processes that operate without significant human interference of any kind," Boss said.

Boss and Pickup hope to return to Yellowstone Lake to study these formations and chart their stability and erosion patterns.

"That could help determine where to locate park infrastructure and how best to manage the area as a resource for people to enjoy," Boss said. Detailed studies of these features also could lead to better understanding of the geologic history of lake level variations that may be related to inflation and deflation of the caldera as magma moves beneath the surface of Yellowstone National Park.