Beaverhead Rock, a prominent geological feature west of here, was sighted on the afternoon of August 8, 1805, as members of the Lewis and Clark Expedition pulled their canoes up the Beaverhead River toward the Continental Divide; Clark later called it a “remarkable Clift,” and Sacajawea recognized the large promontory and said her people called it “beaver’s head.” Composed principally of Madison Limestone, Beaverhead Rock formed from the remains of tiny marine creatures that accumulated in a shallow sea covering much of Montana about 350 million years ago and, after about 10 million years of accumulation and many more millions of years of compaction, became pale gray limestone common across Montana, eastern Idaho, northern Wyoming, and the Dakotas; in Montana these beds range from 1,000 to 2,000 feet thick and, because they resist weathering and erosion in the state’s dry climate, they form many of its cliffs and ridges. The rock later served as an important landmark for trappers, miners, and traders entering the area, many of whom knew it as Point of Rocks. In 1863, Goetschius built a stage station near here on the well-traveled, deep-rutted road between Bannack and Alder Gulch, part of the Montana-Utah Road and also known as Road Agents Trail because of the robberies along it during the 1860s; the station changed horses for stagecoaches, served meals, provided lodging, was also known as Watson Station, included a hotel, saloon, and post office, and closed in 1881 with the arrival of the Utah & Northern Railroad.