Geologists are continuing to study the Decorah meteorite crater

Model of the Decorah Crater by the US Geological Survey

Staffers from the US Department of the Interior's Geological Survey program were in the Decorah area this week, continuing their exploratory work.

Aerial surveys of the Decorah area were conducted in 2011 and 2012, concentrating on the 470-million-year-old meteorite crater concealed beneath Decorah.  Later aerial surveys included electromagnetic monitoring.

The picture that emerged from these surveys confirmed earlier surveys and showed a crater filled with electrically conductive shale.  "The shale is an ideal target and provides the electrical contrast that allows us to clearly image the geometry and internal structure of the crater," said USGS geophysicist Dr. Paul Bedrosian, who is leading the project.

The surveys have revealed a nearly circular region underneath Decorah that is distinct from the surrounding area.  The crater goes to a depth of several hundred meters.  More analysis of the data will provide additional details.