A north-south stratigraphic cross section illustrates lithologies, facies, general thickness changes, and rock units of the Mississippian strata which are known only in the subsurface of the Peace River area.

Mississippian sediments were first truncated to the northeast and east by a post-Mississippian pre-Permo-Pennsylvanian unconformity with three further periods of erosion in the more easterly and northerly parts of the area in pre-Triassic, pre-Jurassic, and pre-Cretaceous time. Over 3,000 feet of sediments remain in the thickest known section and represent all the Mississippian units known from mountain areas. Over 1,000 feet of strata present in the British Columbia subsurface have been eroded in the Peace River area of Alberta.

Several of the formations of the Central Plains and Foothills are recognizable. The Exshaw of the Sturgeon Lake area is a bituminous shale-siltstone-limestone sequence which grades northward to shale. The Banff formation, which to the south is a carbonate unit overlain by a clastic zone, thickens northward to a shale facies. Similarly the Pekisko of the northern part of the Peace River area is a dark shale in contrast to the bioclastic limestone facies throughout the rest of Alberta. The Shunda is composed of a series of bioclastic limestones and gray shales over the entire area.

A new formation name, the Debolt is here proposed for a sequence of rocks divided by a thin clastic zone into a 300-foot lower unit of fragmental limestones probably correlative with the Turner Valley of Southern Alberta and a 500-foot unit of dolostones with evaporites possibly equivalent to the Mount Head. Amerada Crown "G"F 23-11 has been chosen as the type well section of the Debolt.

Above the Debolt is a series of clastics, with some carbonates and evaporites considered to be correlative with the Tunnel Mountain. These beds are assigned to the Stoddart, a new formation being proposed by A. T. C. Rutgers at this meeting.

The units Pekisko to lower Debolt inclusive comprise Laudon's Dessa Dawn of the Wapiti Lake surface sections.

The Permo-Pennsylvanian beds, indefinite as to age, are composed of light cherts and dense dolostones overlain by quartz-chert sandstones. Considerable erosion of the Stoddart and Debolt indicates a major unconformity and time lapse before deposition of the Permo-Pennsylvanian over the Mississippian.

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