On October 28, 1983, a major earthquake fracture 26 miles long and 7 miles deep surfaced as Lost River Valley slid away from Mount Borah. During that rock shift, Mount Borah’s ridge front rose about 6 inches, while this valley subsided 9 feet. This kind of movement has been going on here for 10 to 20 million years as subsurface rock has been pulled apart during gradual but persistent range and valley building. A spectacular fracture that shattered this side road lies 2 1/2 miles from here.