What a neat article Richard. Thanks for sharing this. I haven't learned much about these aeromagnetic maps although I'm aware of them. Got my masters at KU in Geography and GIS and I would sometimes - for headspace - drive out to the flint hills and take a nap in the tall grass prairie preserve. It was very still and quite in the fall, you wouldn't catch chiggers, and I could daydream about what I wanted to do when I grew up, back against earth, and watching cumulus float by. Makes me think what it was like circa 2 billion years ago when this was actual coastline! and exotic terranes were lining up ready to join a more stable craton. All that history was below my back as I lay on those Flint Hills as you point out the evidence of these maps. Such cool stuff, I'm glad I stumbled upon your substack page via your FB "History of the Earth" blog where you did daily posts for a year describing all of geologic history on Earth. -That should be enshrined, what an awesome series.. I'm still deep diving that. Have a good day sir!
Thanks for the nice words, much appreciated! I'm glad you find the posts interesting as well as the History of the Earth blog/podcast. Feel free to ask questions!
Interesting visuals of what is under the prairies and also the various segments of Central and Western North America. With an interest in Assembling Colorado, as presented by Abbot & Cook and others, I have been curious about why the Mid-continent Rift System bends at Lake Superior into a U-shape and heads down through lower Michigan. What forces may have been involved. I would expect a mostly linear trend like Africa or Nevada.
Mostly linear, yes, but consider the geometry at the north end of Lake Malawi, where the general trend turns from nearly north-south to much closer to west (albeit stepping in short NNW-SSE grabens). Alternatively, what if Lake Superior was an incipient triple junction, with the third (failed, or failed to even start) arm heading north toward Lake Nipigon? (I know of no evidence for that, but the Minnesota arm and the Michigan arm aren't too far from the geometry of two branches of a triple junction). Still, the relatively smooth U-shape as you point out, is still there in magnetic data, so it does not seem to show the step-wise breaks we might expect near a triple junction.
What a neat article Richard. Thanks for sharing this. I haven't learned much about these aeromagnetic maps although I'm aware of them. Got my masters at KU in Geography and GIS and I would sometimes - for headspace - drive out to the flint hills and take a nap in the tall grass prairie preserve. It was very still and quite in the fall, you wouldn't catch chiggers, and I could daydream about what I wanted to do when I grew up, back against earth, and watching cumulus float by. Makes me think what it was like circa 2 billion years ago when this was actual coastline! and exotic terranes were lining up ready to join a more stable craton. All that history was below my back as I lay on those Flint Hills as you point out the evidence of these maps. Such cool stuff, I'm glad I stumbled upon your substack page via your FB "History of the Earth" blog where you did daily posts for a year describing all of geologic history on Earth. -That should be enshrined, what an awesome series.. I'm still deep diving that. Have a good day sir!
Thanks for the nice words, much appreciated! I'm glad you find the posts interesting as well as the History of the Earth blog/podcast. Feel free to ask questions!
Interesting visuals of what is under the prairies and also the various segments of Central and Western North America. With an interest in Assembling Colorado, as presented by Abbot & Cook and others, I have been curious about why the Mid-continent Rift System bends at Lake Superior into a U-shape and heads down through lower Michigan. What forces may have been involved. I would expect a mostly linear trend like Africa or Nevada.
Thanks
Mostly linear, yes, but consider the geometry at the north end of Lake Malawi, where the general trend turns from nearly north-south to much closer to west (albeit stepping in short NNW-SSE grabens). Alternatively, what if Lake Superior was an incipient triple junction, with the third (failed, or failed to even start) arm heading north toward Lake Nipigon? (I know of no evidence for that, but the Minnesota arm and the Michigan arm aren't too far from the geometry of two branches of a triple junction). Still, the relatively smooth U-shape as you point out, is still there in magnetic data, so it does not seem to show the step-wise breaks we might expect near a triple junction.