These piles dot the northern half of Thunder Bay near Alpena. Each circle is roughly 15m in diameter and some contain lumps of coal.

These piles dot the northern half of Thunder Bay near Alpena. Each circle is roughly 15 meters (49 feet) in diameter and some contain lumps of coal. Image courtesy of Thunder Bay 2010 Expedition, NOAA-OER.

 

Related Links

Thunder Bay 2010: Cutting Edge Technology and the Hunt for Lake Huron’s Lost Ships

Thunder Bay 2010: Mission Summary

NOAA Ocean Explorer Gallery