Replies

There are a couple of plutons in Southern Indiana ~ the ones we know about the most are on a line with Martinsville, Crothersville and Cincinatti. Martinsville used to have a lot of hotsprings. That one is big enough it reaches as far South as Paoli, Indiana and may even be the source of heat for a couple of others just East of Bloomington.

The pluton at Crothersville actually makes its presence known with a CIRCLE that shows in the soil type at the surface. The down wind area in Jennings County Indiana has a feldspar based soil ~ fairly typical of a sort of ancient volcano.

So this sucker has been toking off and on for probably a couple of hundred million years spewing stuff on Jennings County. That suggests there's an even deeper heat source closer to the mantle ~ maybe a plume like the one under under Oregon, Idaho and Wyoming (Yellowstone).

The only advantage to these hot spots is they weld the cracks overhead. Obviously it's not doing a good job gluing the Mississippi faults back together, but maybe this is their cause!

We have an ancient volcanic vent in Fairfax county just like the one at Crothersville. It's been covered over for tens of millions of years, but it is detectable at the surface. The headquarters for the Coast and Geodetic Survey is there ~ and the main driveway out front CIRCLES THE TOP! Very cute way to tell us about it.