January 7th is Old Rock Day!! When you think of old rocks, it’s hard not to think of Devil’s Lake State Park and the Baraboo Hills range. Consider this; The Baraboo hills, the bluffs surrounding Devil’s Lake, are older than the Rocky Mountains. The Baraboo hills are older than Mt. Everest and the whole Himalayan mountain range!
Current science says that the Rocky Mountains were formed about 300 million years ago. The Himalayan mountains are now thought to be about 450 million years old. The Baraboo hills, now get this, are about 1.6 BILLION years old!! Back when our bluffs were forming, the Rockies were still just a twinkle in our continental crust!
Another interesting note about the Baraboo hills is as you can guess, they were much taller than they are today. However, they weren’t so much worn down as they were buried. Over eons the ground surrounding the bluffs has built up around them until only what you can see was left above ground. The much of the Baraboo bluffs are sunken far beneath our feet.
So what is Old Rock Day? Well, I had to look it up. According to the Days of the Year website, “Old Rock Day” is “the day that Geologists and amateur rock enthusiasts take it upon themselves to show their appreciation of all things fossilised and stony.” They continue to say, “This is also the day when young children are often encouraged to go out and discover their first “pet rock.” It is a day that they can use to bond with their “pet” and cement the very beginning of their lengthy future relationship. ” You can read more here..
Here at Devil’s Lake we have some great pet rocks from Devil’s Doorway & Balanced Rock and my personal favorite, “Elephant Rock” which really looks more like a bison than an elephant but it seems our forefathers were in need of spectacles when they named it. Elephant Rock is just a short jaunt up the East Bluff trail, just past Elephant Cave. (Which by the way, is more of a rocky divot than a cave!). If you look closely you can see that the rock was actually more of a table and some point in the distant past. Then it’s possible that the tall waves of an ancient sea (About 100-500 million years ago) pulled it over, creating the bison, (I mean elephant) we see today.
If you’d like to learn more about Devil’s Lake Geology, check out Robert H. Dott’s Roadside Geology of Wisconsin. You may also want to check out Ancient Rocks and Vanished Glaciers by Ken Lange. Ken also has a new book available called Songs of Place which is certainly worth checking out as well.
Happy Old Rock Day!!
(Thanks to DLK Naturalist, Sue Johansen for her assistance with the numbers!!)