Oil geologist found massive salt domes in the Gulf of Mexico. They were created maybe 60 million ears ago when Africa seperated from South America and sea water flowed in a like at stone and evaporated
This area used to be under the sea, quite a while back. The salt domes trap oil, which Michigan has a little of. A water well driller mentioned that all the wells he drills 7 miles or so west of here are shallow, because if he goes too deep he always hits salt water. That’s been done there a loooong time.