Imagine this area over two billion years ago, covered by the waters of an ancient Precambrian sea. This ocean deposited sand on the sea floor, and these ripple marks on the rocks in front of you formed by wave action in the sand.
Over time, the sand grains cemented and transformed into sandstone, and eventually, with more heat and pressure, into quartzite, a very hard rock. This process preserved these ripple marks.
For the next several hundred years, extensive weathering and erosion reduced the surrounding region to a flat "peneplain." However, Rib Mountain, with its hard, resistant quartzite, projected high above this surface.
Then, about 600 million years ago, expanding oceans covered Wisconsin, depositing thousands of feet of sediment. Slowly, these layers of sediment wore away, once again revealing Rib Mountain and its ancient ripple marks.
[caption] Pictured above are algal stromatolites composed of blue-green algae, bacteria, and silt on the bottom of the Pre-Cambrian Sea. They are believed to be the first life-forms to colonize the earth.