Devil's Backbone Road Cut

This sliced-open ridge is a window into a vanished sea. The wall of the road cut exposes layers of Fayetteville shale topped by Pitkin limestone, sediments laid down in a shallow ocean that once covered the southern Ozarks as the Mississippian geologic period drew to a close, more than three hundred million years ago.

Look closely and you will see the two kinds of rock alternating, what geologists call interbedded. Shale dominates near the bottom, limestone near the top. Those bands may record ancient storms that periodically washed limestone-forming material out into deeper water where the clay of the shale was settling.

The original cut was blasted through in nineteen twenty-eight. Crews returned in the early nineteen seventies to widen and straighten it for modern traffic.