The Belle Fourche arch, a subtle northeast-trending paleoarch, extends across the central part of the Powder River basin, Wyoming, to the Black Hills uplift. The arch is the result of differential vertical uplift, primarily during Cretaceous time, on numerous northeast-trending structural lineaments. Lineament trends are identified from structural offsets in the Black Hills monocline, offsets in well-defined linear topographic escarpments, and by linear drainages which connect trends between the monocline and the escarpments. Underlying basement zones of weakness are thought to be shear zones of Precambrian age analogous to the Mullen Creek-Nash Fork shear zone of southeast Wyoming. Stratigraphic evidence suggests that the structural lineaments which form the Belle Fourch arch have rejuvenated periodically throughout the Phanerozoic. Subtle movements along the lineaments have affected depositional environments and hydrocarbon accumulation in virtually all significant reservoirs in the northern two-thirds of the basin. Evidence includes: (1) localization of Minnelusa Formation (Permian) hydrocarbon production along the crest of the arch; (2) localization of Dakota Formation (Cretaceous) alluvial point-bar production on the crest of the arch; (3) localization of lower Muddy Formation (Cretaceous) channel deposits parallel with, and on the downthrown sides of, lineament trends; (4) abrupt change in depositional strike of upper Muddy Formation (Cretaceous) marine bars close to the arch; (5) superposition of Turner sandstone (Cretaceous) channel deposits alon the trends of Muddy channels; and (6) localization of virtually all significant Upper Cretaceous Shannon and Sussex sandstone offshore marine-bar production along the crest of the arch. Subtle uplift along the arch was persistent during at least lower Muddy through Sussex deposition, a period of about 35 m.y.