SC, the Clovis points we got out of the well we dug on our lot in Indianapolis kinda proved that Clovis were there BEFORE the Younger Dryas ~ because the returning cold climate, and more moving ice, and the continuing drainage of the Ice Sheet through what is now Central Indiana covered the Clovis materials up with a layer of dirt.
This was maybe 20 to 30 miles south of the furthest advance of some really really tall ice ~ well over a mile. Kind of the melt limit on the ice so there was grass, etc. while the rest of the Midwest was still pretty much an iceage desert.