The Monongahela National Forest includes some major landform features such as the Allegheny Front and the western portion of the Ridge-and-valley Appalachians. Within the forest are most of the highest mountain peaks in the state, including the highest, Spruce Knob (4,863 ft), also the highest point in the Alleghenies. Approximately 75 tree species are found in the forest. Almost all of the trees are a second growth forest, grown back after the land was heavily cutover around the start of the 20th century. Species for which the forest is important include red spruce (Picea rubens), balsam fir (Abies balsamea), and mountain ash (Sorbus americana).