When the Wisconsin River Flowed North through Shawano
Beneath the fields and forests around Shawano lies the buried valley of an ancient river that once carried more water than the modern Wisconsin River.
The Hidden Story
If I told you that one of Wisconsin's largest rivers once flowed the opposite direction, would you believe me? Right beneath our feet, hidden under hundreds of feet of glacial sediment, lies the valley of an ancient river that may have changed the course of Wisconsin's history.
What We Know
Beneath the Shawano area lies a broad buried bedrock valley carved by an ancient river system before the Pleistocene glaciations.
The valley is now filled with glacial sediments, so its full size and shape cannot be seen from the modern land surface.
The buried valley extends well beyond the present-day Wolf River and Shawano Lake and is significantly larger than either feature.
Modern geological mapping, well records, and other subsurface investigations have documented the depth, extent, and general geometry of this buried valley.
The valley formed before continental ice sheets advanced across Wisconsin during the Ice Age. Later glaciations modified the landscape and buried the ancient river system beneath thick glacial deposits.
Although hidden from view, the buried valley continues to influence the region by affecting groundwater flow, sediment distribution, and parts of the modern drainage network.
Without geological mapping, well records, and other subsurface data, there is little at the surface to suggest that such a large ancient river valley lies beneath the Shawano area.
The buried valley has been studied by professional geologists and is recognized as an important component of northeastern Wisconsin's geologic history.
Questions That Remain
How precisely can the buried valley be mapped?
Existing bedrock elevation data are too sparse in parts of northeastern Wisconsin to confidently trace the valley's exact route. Additional well logs, drilling, and geophysical surveys could significantly improve our understanding.
How deep is the buried valley along its entire length?
Some portions are well documented, while others remain poorly constrained due to limited subsurface information.
Exactly when did the Wisconsin River abandon this ancient course?
The general sequence of glacial events is understood, but the precise timing of drainage changes continues to be refined.
Were there multiple episodes of valley erosion?
Did one ancient river carve the valley, or was it modified by several rivers over millions of years?
Are there additional buried tributaries?
Smaller valleys may still lie hidden beneath glacial sediment and have yet to be identified.
How does this buried valley continue to influence today's landscape?
Researchers continue to investigate how the buried valley affects groundwater flow, wetlands, sediment thickness, and the locations of modern rivers and lakes.
The Big Picture
The landscape we see today is only the surface of a much older world. Beneath Shawano lies the buried valley of an ancient river that still influences the region, proving that some of Earth's greatest stories remain hidden beneath our feet.
Keep Exploring
This is the story as I understand it today. If it sparked your curiosity, I encourage you to keep exploring. The buried valley beneath Shawano is part of a much bigger story than I could tell in one visit, and geologists like Dr. Eric Carson have done outstanding work explaining it in greater depth. Adventures in Place is about discovering remarkable places and asking better questions. I hope this story inspires you to look a little more closely at the landscape around you—and perhaps discover that some of Wisconsin’s biggest stories are hidden beneath your feet. I’ll almost certainly return to this ancient river system in future Adventures in Place stories as we visit other locations that reveal different pieces of the puzzle.
Contributors
Dr. Eric Carson — Geologist whose research and public presentations helped explain the buried river valley beneath the Shawano area.
Sources & Further Exploration
The River That Flows Uphill: Geologic evolution of the upper Mississippi River Valley
Eric Carson, Ph.D, WGNHS
Adventures in Place 