Glacial influence on deposition of the upper Proterozoic Sayunei and Shezal Formations (Rapitan Group) of northwestern Canada is well established. Diamictites of the Stelfox Member of the Ice Brook Formation, 1 km higher in the section and resting on platformal carbonate and siliciclastic strata of the Keele Formation, are here interpreted as glaciomarine. The glacial interpretation is based on the presence of dropstones, till pellets, extremely angular quartz grains, intercalations of laminated mudrocks and sandstone, and rare striated stones. The Stelfox glacial deposits are unique in that they lie above the lowest occurrence of faunas of Ediacaran type.

The establishment of two episodes of Late Proterozoic glaciation in northwestern Canada, as opposed to the previously recognized single episode, enhances the possibility that these two glaciations correspond to the two recognized in parts of Australia and Africa.

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