May be the first connection I've seen too. Albeit, RightWhale may have spoken of a connection in the past.
When I was much younger some people I used to know then used to smoke some kind of tobacco and then come out with these kinds of revelations.
When Lake Agassiz broke out it flooded all the way down the Mississippi and carried all of Canada's topsoil down to Illinois and even Oklahoma. The weight was also unsettling to the region and perhaps contributed to the new Madrid series of earthquakes, but at least the soil was still loose enough to be greatly disturbed during the earthquakes. Later the Dust Bowl moved much of that topsoil again, which surprised some people but shouldn't have since it was recently deposited and wasn't that well rooted.