The Geology of Rocky Arbor

The rock forming Rocky Arbor's gorge is sandstone which geologists have aged at about 500 million years. Its sand grains are thought to have been deposited by rivers draining into shallow seas. The seas receded, and the sand compacted into sandstone.

The rock outcrops show the layers of one-time river deposits.
DNR Photo by Joe Warren

Eons later, the Wisconsin River cut a gorge through this stone and thus formed the park's picturesque rock walls and ledges.

Long since, the river changed its course and now flows about a mile and a half to the east. The tiny stream that now occupies the gorge actually flows in the opposite direction that the mighty river did when it carved this scenic area.

For more information, ask Steve Rodenkirch, (608) 254-8001 Memorial Day through Labor Day, (608) 254-2333 the rest of the year.