Calvin crater

Template:Short description Template:Infobox terrestrial impact site Calvin is an impact crater located in Calvin Township, Cass County, in the U.S. state of Michigan. It was discovered in 1987 by Randall Milstein of the Michigan Geological Survey while examining data from about 100 test wells drilled in the area.<ref name=um>Template:Cite web</ref>

It is Template:Convert in diameter and the age is estimated to be 450 ± 10 million years (Ordovician).<ref>Template:Cite Earth Impact DB</ref> The crater is not exposed to the surface. It lies about 100 to 400 feet (30–120 m) below today's ground level.<ref name=um />