Glacial Signatures Written on the Land

Ten thousand years ago, at the end of the last ice age, Vilas County was locked under a solid layer of ice. The glaciers are long gone now, but you can still see evidence of them everywhere you look. I wrote over the summer about how the retreating glaciers formed the kettles that are now our many lakes and bogs – this county has the highest density of natural freshwater lakes of anywhere in the world. The lakes may be the most obvious signature the glaciers left behind, but they’re not the only one.

The photo above was taken standing on top of an esker – you can see that you’re looking along a ridge that drops off on either side.

Eskers are formed by streams of liquid water flowing under and through glaciers. As it flowed, the stream deposited a ribbon of gravel and sediment between the ice walls surrounding it. When the glacier retreated, this is what was left behind. Ours snakes along the margin of one of our kettle bogs.

We also have a lot of till, jumbled collections of rocks and boulders that the glaciers scraped up somewhere else and dumped here. The rocks I flipped for International Rock Flipping Day this year arrived on the property this way.

Was the area where you live ever glaciated? How can you tell?

Further reading: Pleistocene Geology of Vilas County, Wisconsin

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One thought on “Glacial Signatures Written on the Land”

  1. In my neck of the woods folks started to move in or back into the area around 11 or 12 thousand years ago as the glacier retreated, Presently folks are exploring a Paleo-indian site near Debert NS Canada where I often gathered wild food in the 1980 & 1990s, I personally find the dance of glaciers during the cycling of ice ages fascinating. another great post

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