Peninsula State Park Professional Review and Guide
"Peninsula State Park was developed in 1909 from a protruding section of Door County that was, until that time, heavily logged and farmed. The area is a geological wonder made up of sandstone and limestone which accumulated millions of years ago at the bottom of a prehistoric sea. The area, along with the rest of Door County, is part of the Niagara Escarpment, the massive shelf of rock that extends from Lake Winnebago to Niagara Falls, New York.
The terrain the mountain bike trails cover has more recently been scoured and compressed by glaciation, the same glaciers that carved out the surrounding waters of Green Bay. Sighting a red-tailed hawk perched along the trail is not at all uncommon. Elevation Change: While there are quite a few flat stretches, small rolling hills make up the majority of the terrain. Small climbs are commonplace, none over 30 feet in elevation."