Map 3 Milepost 25.0 to 40.0

31.5 Thornton Gap Entrance Station

31.7 Panorama

Marys Rock Tunnel

The tunnel, 670 feet long, was bored through the solid granite of Marys Rock in 1932. Although justified as avoiding the necessity of creating an expensive cut on the existing slope and filling the down slope areas, thus creating a massive man-made, visual feature, it has been suggested that the tunnel was built as a challenge to Bureau of Public Roads and National Park Service landscape architects. 

The tunnel was partially lined with concrete in 1958 to alleviate the formation of icicles in winter and water seepage in summer—a partially successful effort.

36.7 Pinnacles

This picnic area is open year-round. It is large and scenic, offering families a pleasant place for relaxing. There are picnic tables with grills nearby; accessible sites are available. Restrooms (open except in cold months) are accessible with assistance.