Many travelers find the midwestern United States flat and boring. But the dull landscape actually covers a turbulent past, a new set of 3D maps reveals.
In the Western states, glaciation was sparse and the rocky geology is commonly in plain view. Not so in the Midwest. To get a better grip on the region's geology, four midwestern states are collaborating with the U.S. Geological Survey to produce maps that reveal the shape of things more than 150 meters underground.
The first maps made by the 4-year-old Central Great Lakes Mapping Coalition combine surface topography with seismic studies and deep drilling. Just released, they detail the geology of select Chicago suburbs; the Fort Wayne, Indiana, region; and southwestern Michigan. Mappers are finding "far more variability than had been thought and considerable insight into glacial processes and deposition," says geologist Richard Berg of the Illinois State Geological Survey in Champaign. Repeated advances and retreats of glaciers in the Midwest have, over time, "piled one landscape over another and created a very complex array of buried deposits."
Stephen Marshak, a geologist at the University of Illinois, Urbana-Champaign, calls the effort "a very new tilt on geological mapping."
Central Great Lakes Mapping Coalition
U.S. Geological Survey Earth Resources Observation Systems Data Center
3-D Geologic Mapping in East-Central Illinois
Three-Dimensional Geologic Maps of Quaternary Sediments in East-Central Illinois