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 (1569). This preliminary study is based on 29 measured sections of the Lisburne Group (fig. 1, see. 1-25). The outcrops are from near Cape Lisburne⁽¹⁾ in the west to Egaksrak River ⁽²⁹⁾ in northeastern Alaska and are used as the basic building blocks for the carbonate facies maps and the one cross section. The construction of the carbonate facies maps are based upon, 1) arbitrary palinspastic reconstruction of the sections ( fig . l), 2) the assumption in Early Mississippian time of a low-lying, somewhat peneplained cratonic shelf to the north of the Brooks Range, and 3) the development during Mississippian time of a marine transgression onto this shelf.