 The Grand Canyon of Pennsylvania is known for its fall foliage , and Leonard Harrison State Park is a popular place to observe the colors , with the first three weeks of October as the best time to see the leaves in their full color . Red leaves are found on red maple , red oak , and black cherry , while orange and yellow leaves are on black walnut , sugar maple , aspen , birch , tulip poplar and chestnut oak , and brown leaves are from beech , white oak , and eastern black oak trees . Plants of " special concern " in Pennsylvania that are found in the gorge include Jacob 's ladder , wild pea , and hemlock parsley . 
