Ross' Hole is a valley located in Ravalli County, in Sula State Forest, along U.S. Route 93 in the vicinity of the hamlet of Sula, Montana. It was named after fur trader Alexander Ross, leader of a Hudson's Bay Company trapping brigade, who camped there in 1824. According to the Encyclopedia of the Lewis and Clark Expedition, "Hole" was a term u…Ross' Hole is a valley located in Ravalli County, in Sula State Forest, along U.S. Route 93 in the vicinity of the hamlet of Sula, Montana. It was named after fur trader Alexander Ross, leader of a Hudson's Bay Company trapping brigade, who camped there in 1824. According to the Encyclopedia of the Lewis and Clark Expedition, "Hole" was a term used by trappers for a broad, flat valley surrounded by mountains.