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Sideling Hill Cut of I-68
Geological Feature
At Hancock, Interstate 70 heads north from Maryland into Pennsylvania. U.S. 40 and I-68 continue westward, following the route of the National Road to Cumberland and beyond. A huge cut through the mountain now marks the route of Interstate 68 west of Hancock.
The National Road was the first federally funded highway in the U.S., authorized in 1806. Towns in Washington County celebrate the National Pike Festival in May. Towns along the pike have events featuring Conestoga wagons, buggies, mules, and horses. For information, contact the Washington County Tourism Office at 301-791-3130.
The Sideling Hill road cut is one of the most striking geologic windows in the entire Appalachian region, created in the mid-1980s when Maryland engineers carved a 340-foot-deep notch through the ridge to complete the final segment of the National Freeway. What the excavation revealed is a spectacular, textbook-quality cross-section of the Ridge-and-Valley province: tightly folded layers of Devonian sandstone, siltstone, and shale bent into a massive syncline about 350 million years old.
The cut exposes more than 20 distinct rock formations and vividly shows how ancient tectonic collisions compressed and warped the landscape long before the Potomac carved its valley nearby. For decades, the site included a popular visitor center and pedestrian bridge, and even though the facility has since closed, the cut remains a landmark--an open-air geologic museum that turns a routine highway drive into a glimpse of deep time.
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Contact Information
Maryland Dept. of Natural Resources
14038 Blairs Valley Road
Clear Spring MD 21722
301-842-2072
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