The subsurface Notikewan Member (Spirit River Formation) of the Fort St. John Group is correlative with the upper 60 to 70

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m of the Gates Formation in northeastern British Columbia. The basal Notikewan is a thin pebbly transgressive lag deposit overlying carbonaceous nonmarine shales, sandstone, and locally conglomerates of the Gates (Falher equivalent). Overlying the transgressive lag is a 5 to 10 m fining-upward transgressive phase of interbedded sandstone or conglomerate and shale. The sandstones are hummocky cross-stratified and the conglomerates are molded into symmetrical gravel dunes (both features indicate storm processes were common during the transgression). The regressive phase is a 20 to 30-m coarsening-upward sequence showing much less evidence of storm influence. Locally 10 to 20 m thick sandstone channels cut through the shoreline into marine sediments. The precise location of the shoreline is generally difficult to pick, unlike in the underlying Falher cycles. Specimens of Ostrea above the channel sandstones suggest a brackish-water depositional environment. The Ostrea are a good local stratigraphic marker in the Bullmoose Mountain area, in some places forming banks. Sedimentary structures in interbedded sandstones, siltstones, and shales, and reversing paleoflow directions suggest a low-energy shoreline dominated by tidal flat and, possibly, estuarine processes. Paleocurrent data indicate that shoreline orientation was generally east-west. This is in marked contrast to the high-energy wave dominated shorelines of the Fahler. The upper 20 to 30 m of the Notikewan is nonmarine floodplain and overbank deposits with thin (< 1 m) coals, lagoonal shales and siltstones, and r re channels.

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