NOTES ON CHANGING PALEOENVIRONMENTS ACROSS THE CRETACEOUS-TERTIARY BOUNDARY (SCOLLARD FORMATION) IN THE RED-DEER-RIVER VALLEY OF SOUTHERN ALBERTA

The Scollard Formation of southern Alberta comprises alluvial plain de posits that straddle the Cretaceous-Tertiary boundary. Paleochannels i n the Scollard Formation display an apparent shift from low sinuosity (straight) to higher sinuosity (meandering) channel forms across the b oundary, coincident with the onset of deposition of peats and organic- rich muds. A superb example of this transition is preserved at Knudsen 's Coulee and is herein documented. Although a tectonic influence cann ot be ruled out, we propose that the principal cause of the transition is climatic, the result of an increase in wetness, locally rising wat er tables, and possible changes in discharge characteristics and in-ch annel sediment load. On the basis of parsimony and the absence of evid ence to the contrary, we reject the suggestion that the Cannonball tra nsgression directly influenced changes in the depositional style of th e Scollard Formation.