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Mastodon
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Ice
Age Indiana Resources Center for Earth and Environmental Science EXCAVATING THE ICE-AGE MASTODON IN
CENTRAL INDIANA Abstract In late 1976. Mike Christensen uncovered some bones in a boggy field on his farm in Hancock County, located 27 km (17 miles) east of downtown Indianapolis and 10 km (6 miles) north of Greenfield. Dr. Arthur Mirsky identified the bones as part of a now- extinct ice-age mastodon (Mammut americanum), and expressed an interest in excavating the rest of it. Mike Christensen gave his approval and the excavation project began in late March, 1977 and ended in early October, 1977. The scientific work was done under IUPUI Geology faculty: Dr. Arthur Mirsky, supervisor of the excavation, recorder, and general paleontology; Dr. Russell W. Graham, vertebrate paleontology; Dr. Robert D. Hall, soils and stratigraphy; and IU-Bloomington Biology faculty Dr. Donald R. Whitehead, pollen analysis. Among those organizations who actively cooperated with the IUPUI Department of Earth Sciences in various phases of the excavation were the Indianapolis Amateur Archaeological Association, the Strubbe Gravel Company, the James H. Drew Corporation, the Marion County Civil Defense Fire Rescue Unit, the Indiana University Foundation, and the Children's Museum Guild. The excavation was done by a total of 102 volunteers, ranging from those who worked most of the excavation-days to those who worked only a few hours on a single day. Whatever, without the help of these cooperating organizations and volunteers, the excavation could not have been completed. And, as it turned out, the excavation was a resounding success. About 20,000 years ago, much of Indiana from Michigan south to Martinsville was covered by a glacial ice sheet many hundreds of meters thick. Then the ice began melting back northwards until, about 10,000 years ago, the glacier was gone from the state. As the ice retreated, it left behind many areas that became bogs, one of which was the boggy field on the Christensen farm. Excavation of this bog revealed 5 stratigraphic layers, which from bottom to top, are: (1) light-colored outwash sand that had been washed out from the retreating glacier, (2) black, laminated lake beds, 2.5-4 m thick, with no apparent fossils, (3) yellowish, silty laminated lake beds, 0.3-1 m thick, with mollusk shell fragments, some wood, and some bones of mastodon and fish, (4) dark-colored massive peaty clay, 1.3-3 m thick, with many mollusk shell fragments, much woody material, and most of the mastodon bones, and (5) light-colored surface deposits of slopewash, 0.5-2 m thick, with no fossils.
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