Or is Mark only assuming I got it?
Truth be told, Google does a world of good on things like this one. That, and knowing chert is often called flint, and that the Flint Hills have much in the way of novaculite, a grainy form of chert. That, plus knowing pfemm resides in or near Oklahoma. So, chert + byway + Oklahoma brought me close, and chert + byway brought me Flint Hills, and a link to a state by state scenic byways website brought me to a road map, where I determined it's NOT a loop but does intersect I-35.
Now watch me be wrong on this SWAG after all.
Foy