Carbonate porosity within the Mississippian-Pennsylvanian age Lisburne Group is probably extensively developed in the subsurface of the North Slope. The Lisburne Group may prove to be one of the more significant reservoir zones in the region and should not be overlooked in any exploration program. Isopach maps for the total Lisburne Group and other upper Paleozoic and Mesozoic rocks, North Slope, can be found in Brosge and Tailleur (1969).