Sideling Hill Welcome Center

The road cut through Sideling Hill is the kind of thing you can see from miles away — a deep V-shaped notch punched clean through what would otherwise be an unbroken ridge. When I-68 was built in the 1980s, crews blasted through the crest of the mountain, and the work exposed something geologists had not seen at this scale in the region: a tightly folded syncline with nearly 810 feet of strata visible in a single cross-section. The Maryland Geological Survey calls it one of the best rock exposures in Maryland and the entire northeastern United States — not because of thickness alone, and not because of structural quality alone, but because few sites match both at once. The layers arch in a broad U-shape up both walls of the cut, a visual record of ancient seafloors and river systems compressed over hundreds of millions of years by continental collision.

The Welcome Center building sits on the westbound side and connects to the eastbound rest area by a pedestrian bridge that spans the highway. That bridge is the reason to get off the bike: standing on it puts the full geometry of the cut in front of you, the road threading through the gap far below, ridgeline above on both sides. Inside, a four-level exhibit and a geological time spiral give context to what you just rode through. The center operates Thursday through Monday, 8:30 a.m. to 4:30 p.m.; the rest area and parking lot are accessible around the clock. Note that the center is closed on major holidays, so verify hours before planning a stop around the exhibits specifically.