Geology of the 400 Trail

Geology of the 400 Trail. Glacial Lake and Sandstone Bluffs. If you had been here 12,000 years ago, you would be standing at the bottom of an 1825 square mile lake called Glacial Lake Wisconsin. It was formed when glacial ice blocked the Wisconsin River, allowing water to back up to Stevens Point. The valley you are in was a long narrow bay of the lake with surrounding sandstone bluffs as the shoreline. The flat lake left an ideal path for building a railway that became the 400 trail!, The large sandstone outcrop seen beyond this sign is known locally as the "Third Castle." It stood as an island in Glacial Lake Wisconsin. The name "Castle" comes from the fact that these rock bluffs reminded European settlers of the walls of castles from their homelands. First and second castle are located to the left but are not clearly visible from here. The castles are on private property so can only be enjoyed from this view., The area north of Third Castle is shaded most of the day. This creates a cool climate where hemlock trees, normally found farther north, can grow in the cliff’s shade.