Several glaciers sculpted this landscape, and as the last glacier receded north more than 10,000 years ago, its meltwaters helped carve Pine Creek's deep gorge, which the creek's waters continue to gradually deepen today as Pennsylvania's Grand Canyon. Humans also shaped this land: in the 1890s Leonard Harrison operated a lumber mill at Tiadaghton in Pine Creek Gorge, where loggers felled massive white pines and floated log rafts down Pine Creek to Williamsport sawmills. George Washington Sears, a well-known outdoor writer who used the penname "Nessmuk," lived in Wellsboro for most of his life. By the early 1900s, deforestation, forest fires, and unregulated hunting had taken a heavy toll on wildlife, leading Pennsylvania to begin purchasing private lands to create state forests and parks and to reintroduce white-tailed deer, beaver, elk, river otter, and fisher to this area throughout the 1900s. Leonard Harrison State Park honors Leonard Harrison of Wellsboro, who donated the park's original 121 acres to the Commonwealth, and in 1968, 12 miles of the gorge were designated a National Natural Landmark for added protection. The route now followed by the Pine Creek Rail Trail had been traversed by Native Americans for thousands of years before the Jersey Shore, Pine Creek and Buffalo Railroad laid tracks along it in 1883 to carry timber, coal, and passengers; rail service ended in 1988, and the trail now runs more than 60 miles from Wellsboro Junction to Jersey Shore.