No stromatoporid too deep for John Zawiskie

The summer of 2007 found Cranbrook Institute of Science Research Scientist and adjunct Wayne State University Geology Instructor John Zawiskie "on the reefs." But these weren't ordinary reefs. First of all, they are located in the Great Lakes beneath Thunder Bay Island in Lake Huron, approximately 13 miles offshore of Alpena, Michigan. Second, these reefs are Middle Devonian in age - approximately 385 million years old!

The reefs are exposed by low water along the southern end of Thunder Bay Island and continue for 20 feet or more beneath the surface of Lake Huron. They are comprised of wave resistant corals, sponges, and dominantly stromatoporoids - an ancient form of calcareous lime-secreting sponge. The expedition used a combination of surface geology and underwater diving to document the distribution of the Devonian reef complexes.

From a scientific standpoint, these reefs are important because they: 1) provide insights into Michigan's geologic history; 2) represent an important commercial resource (cement is made of limestone); and 3) give us information about carbonate sediments (limestone and dolostone rocks) that constitute the largest reservoir of carbon in the Earth's crust.

This scientific expedition resulted from a collaborative effort among the Noble Odyssey Foundation, the Great Lakes US Naval Sea Cadets, the National Oceanic and Atmospheric Administration, the Michigan Department of Environmental Quality, the Cranbrook Institute of Science and Wayne State.