The Suitcase Lady


October 10, 2017, 8:16 pm

Geology rocks……literally. Look up America’s top natural attractions and you will be looking at the Grand Canyon, Rocky Mountains, Zion and Bryce National parks, Yellowstone and Yosemite.

Our rocks here in Wisconsin aren’t on the list, but they should be. Wisconsin is home to part of a world famous geological formation that runs through the eastern third of the state and then through the Upper Peninsula of Michigan into Canada and down to Niagara Falls. This massive, 1,000 mile stone ledge is called the Niagara Escarpment.

The Escarpment plays a game of hide and seek. In some places such as Door Country, High Cliff State Park and Horicon Marsh it is unmissable. But in other places it is underground, only to pop up a few miles later.

The geology of the Escarpment is fascinating. Essentially, it is the rim of a vast, ancient sea that formed 430 million years ago in the Silurian Period. In comparison, that makes the 70 million year old Rocky Mountains mere kids.

The rock was originally lime mud on the sea floor. What we see now is the result of “uplift, weathering and erosion”. When the sea dried up, the layer that was soft shale eroded quickly, the harder dolomite limestone remained. A close inspection of these dolomite cliffs reveals wonderful sea fossils such as corals, cephalopods and chrinoids.

More than 10,000 years ago (modern history in geological time) glaciers covered the eastern part of Wisconsin. Those mile thick frozen rivers of ice acted like bulldozers knocking down the Escarpment in some places and creating fissures and caves in others.  So we can blame the glaciers for the “now you see it, now you don’t” aspect of the formation.

Geologists classify the Escarpment as a cuesta, which is a ridge with a gentle slope on one side and a steep slope on the other. In Wisconsin’s Door County, the cliff is on the Green Bay side and the gentle slope on the Lake Michigan one.

People have been drawn to the Escarpment from the earliest times. An 11,200 year old projectile point has been found on the Oakfield Ledge in Wisconsin. Pioneers settled near the ridge as well building lime kilns to burn the rocks to produce white lime powder that was used for mortar, plaster and paint. The limestone itself was used to build homes and churches. 500 designated historic sites and structures can be found within two miles of the Escarpment’s path in Wisconsin.

So lift a glass of wine to this amazing piece of geology. And be sure the wine is from an Escarpment vineyard. The slopes and micro climate of the ledges make it ideal for growing grapes. The Wisconsin Ledge Viticulture Area is a federally designated grape growing region of 3,800 square miles from Cedarburg to Door County, Wisconsin. Watch out, Napa. We are more than Cheeseheads.



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