Prolonged eolian action on the barren (prevegetation) craton provides a better explanation for the absence of shale in the Cambrian and Lower Ordovician orthoquartzite-carbonate suite of east-central and Arctic North America than does marine bypassing. It is hypothesized that paleo-trade winds transported much of the missing silt and clay to the southern and western United States and southwestern Canada, while the remainder diffused radially off the craton under the influence of variably directed storm winds. The distribution of shale in the Sauk sequence supports this and indicates that the orthoquartzite-carbonate suite of upwind regions is replaced by a shale-carbonate suite in downwind areas.

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