John O'Shea's research and work on prehistoric sites at the bottom of Lake Huron is outlined in a new study discussed in the Great Lakes Echo:

Today, scientists and shoreline property owners pay close attention to annual fluctuations of Great Lakes water levels. But water levels between 8,350 and 9,000 years ago were unusually low, according to a newly published study by Sonnenburg and John O’Shea, the curator of Great Lakes archaeology at the University of Michigan’s Museum of Anthropological Archaeology in Ann Arbor.

The study appeared in the journal Geoarchaeology. The discoveries came along the limestone-capped Alpena-Amberley Ridge — essentially a land bridge — that runs between Alpena and Point Clark, Ontario, 50 to 164 feet below the surface of the lake.There, hunters built the blinds and driving lanes during the last of several post-Ice Age times when the land subsided and rose — a process scientists call isostatic rebound — after the glaciers melted, Sonnenburg said. Lake Huron was completely cut off from Georgian Bay and Lake Michigan.

Scientific evidence illustrates how different the climate was when prehistoric hunters preyed and camped along the Alpena-Amberley Ridge. And “some of the most important questions in human prehistory require the investigations of submerged landscapes,” the study said.

Prehistory found deep in Lake Huron