Thursday, September 13, 2018

Devil's Lake

Devil's Lake lies in a steep sided gorge that cuts through the southern Baraboo Range about an hour north of Madison. The billion and a half-year old Baraboo Quartzite forms steep cliffs along the edge of the valley and erosion has left an assortment of stones standing alone or leaning against each other. The stones that didn't remain on top are piled in a talus slope along the base of the slopes.


The lake itself is formed between two moraines - left at the western edge of the ice during the last ice age. We're right at the eastern edge of the driftless area, which extends west into Minnesota. Given it's shape and location, I had sort of expected that the gorge was a glacial margin outwash channel, but apparently it's much older and may mark an earlier route of the Wisconsin River. The quartzite is awfully resistant stuff and it makes sense that this gorge was not formed easily or quickly.

I assume the reddish sand beaches are derived from these same rocks. This was one of those sites where you could see primary ripple marks on the quartzite blocks, and then find modern ripples of the same sand on the edge of the lake.