Missing Waterfall

Planning a trip from Tallulah Gorge SP, GA to Fairy Stone SP, VA. While still in the planning, Stage some where along the route we had found a waterfall, that in the past you could drive under. Due to erosion and/or what ever, you can no longer do that, but it is still an interesting place to see.
Well I lost the info I had on it. Anyone familiar with my vague description of it. Almost positive a planned stop was Mt. Airy, if that helps. Didn't help me.

thanks