Cave of the Mounds, in Blue Mounds, Wisconsin
Cave of the Mounds, in Blue Mounds, Wisconsin
Cave of the Mounds, in Blue Mounds, Wisconsin, the bump running upper-left to lower-right is a fossil of a giant cephalopod sea creature which lived 450-500 million years ago
Oolites, or 'Cave Pearls', in Cave of the Mounds, in Blue Mounds, Wisconsin
Cave of the Mounds, in Blue Mounds, Wisconsin
Cave of the Mounds, in Blue Mounds, Wisconsin
Cave of the Mounds, in Blue Mounds, Wisconsin
Cave of the Mounds, in Blue Mounds, Wisconsin
Cave of the Mounds, in Blue Mounds, Wisconsin
Cave of the Mounds, in Blue Mounds, Wisconsin
Cave of the Mounds, in Blue Mounds, Wisconsin
Cave of the Mounds, in Blue Mounds, Wisconsin
Cave of the Mounds, in Blue Mounds, Wisconsin
Cave of the Mounds, in Blue Mounds, Wisconsin