As described by Till and others (2008a), unit consists of “white to gray (less commonly black), fine to coarsely crystalline, massive to platy marble and subordinate metalimestone and dolostone occurs discontinuously in all quadrangles within the map area. |m locally contains abundant disseminated quartz or mica grains, and (or) interlayers of schist, quartzite, or phyllite. In some areas, these strata contain no relict sedimentary textures and few or no fossils; elsewhere, relict sedimentary structures and fossils occur, but rocks have not been studied in sufficient detail to allow assignment to * * *” other better defined carbonate units of Devonian and older age. “Existing fossil data and regional relationships suggest that most |m is Cambrian through Mississippian in age” (Till and others, 2008a). As shown here, unit includes exposures in the Ambler River, Survey Pass, Wiseman, Chandalar, Philip Smith Mountains, Christian, and Arctic quadrangles that were traditionally assigned to the Skajit Limestone of Baird Group, a formal unit not used herein. It excludes part of unit Pzm of Till and others (2008a) in the Baird Mountains quadrangle, which is here included in unit Pzcn