Garrett County is located entirely within the highland zone of the Appalachian Mountains known variously as the Allegheny Mountains, the Allegheny Plateau, and the Appalachian Plateau. The county's highest elevations are located along four flat-topped ridges and range to a height of at Hoye-Crest along Backbone Mountain, the highest point in the state of Maryland. As is typical in the Allegheny region, broad flats generally lie below the ridge crests at elevations of approximately . River valleys are generally narrow and deep, with ravines typically 1,000 to below surrounding peaks.