This interim geologic map shows the general distribution of rock types underlying
Minnesota's landscape. Some of the rocks are 3.6 billion years old - the oldlest found so
far in the United States. The map reflects geologic ideas developed by scientists during the past decade. Because the map was compiled from large-scale maps, large parts of which were interpreted from geophysical data, this image should not be photographically or
digitally enlarged for use at a more detailed scale.