Thunder Bay

Sinkholes

Sinkholes are like a time capsule, taking us back to how Earth may have appeared billions of years ago. In the cold waters of Lake Huron, the limestone, dolomite, and gypsum rocks remind us that the area was once part of a saltwater sea. Over time, these rocks became “karst formations” or underwater caves that eventually collapsed and formed sinkholes. The sinkholes in Thunder Bay National Marine Sanctuary host unique microbial communities, including some that use the sun for energy and some that rely on chemical processes to make their own food. Researchers believe these microbes could provide clues to how organisms were able to survive the harsh and sharply- changing chemical conditions of early Earth.