The Back Forty deposit was formed roughly 1.8 billion years ago around a hot spring on the seafloor. In this type of environment, hot water with high concentrations of dissolved metals and sulfur vent onto the seabed and mix with frigid seawater. The change in temperature and chemistry cause the metallic elements including zinc, gold, and copper to bind with other minerals and settle onto the seabed as metal-bearing minerals. Over the course of time, this accumulation can turn into an economic mineral deposit. Several mineral deposits of this type have been found in our region; including Flambeau, Crandon, Bend, and Lynne.
Scientists first discovered these types of deposits in the 1970s while exploring the Galapagos Islands. The researchers learned that large numbers of organisms depend on the ecosystems formed around these hot springs in the ocean floor. Tubeworms, orange shrimp, eel-like fish, bacteria, and many other deep-sea creatures can be found among the springs.