The Tug Hill Plateau is a roughly elliptical-shaped area located in northern New York State that rises above the adjacent landscape and is underlain predominantly by Middle to Upper Ordovician strata. Its elevated character is interpreted as a passive response to the tectonic uplift of the adjacent Precambrian basement located to the east and northeast of the plateau. Uplift of the basement is also inferred to have resulted in the strata on the plateau and in the topographically lower terrain to the north dipping gently towards the southwest. Tilting of the plateau was probably facilitated by rotation along the newly recognized regionally extensive Black River fault, which separates the plateau from the uplifted basement and marks the plateau’s east-northeastern limit. The northern limit of the plateau, accentuated by a pronounced escarpment, is aligned with the northeast-trending Carthage–Colton shear zone, a major Precambrian tectonic boundary. Uplift of the Adirondack Highlands and Tug Hill Plateau, relative to their counterparts northwest of the shear zone, is believed to have been enabled by reactivation of the Carthage–Colton shear zone.