The Flume Gorge is a natural gorge extending 800 ft horizontally at the base of Mount Liberty in Franconia Notch State Park, New Hampshire, United States. Cut by Flume Brook, the gorge features walls of Conway granite that rise to a height of 70 to 90 ft and are 12 to 20 ft apart. Discovered in 1808 by 93-year-old "Aunt" Jess Guernsey, the Flume …The Flume Gorge is a natural gorge extending 800 ft horizontally at the base of Mount Liberty in Franconia Notch State Park, New Hampshire, United States. Cut by Flume Brook, the gorge features walls of Conway granite that rise to a height of 70 to 90 ft and are 12 to 20 ft apart. Discovered in 1808 by 93-year-old "Aunt" Jess Guernsey, the Flume is now a paid attraction that allows visitors to walk through it from May 10 to October 20. Pets are not allowed.