Physiographic and stratigraphic associations of relatively coarse-grained (mainly sand) deposits, in the Edmonton and Okanagan Valley areas, Canada, illustrate deposition in glaciolacustrine deltas. Sedimentary successions are described in terms of seven facies states: gravel, cross-bedded sand, flat-bedded sand, crosslaminated sand, alternating beds, parallel-lamination, and diamicton. Proportional thickness, preferred vertical position, and transition probabilities together with grain-size and paleocurrent analysis form the basis of detailed analysis of the deltaic successions. A simple succession is recognized in which flat-bedded sands dominate the lower part and cross-stratified sands dominate the upper part. In these successions, paleocurrent directions are consistent, and there is a significant fining-upward trend. The flat-bedded sands are interpreted as multi-storied lateral-accretion deposits of distributary channels. The cross-laminated sands are interpreted as distributary-mouth bar deposits. The succession of stratification and grain-size illustrates deposition in increasingly distal positions during ice-marginal recession. A second type of succession shows complex, broad cyclicity. Rhythmic beds, with a lower member of cross-laminated or alternating beds and an upper member of parallel-laminated beds, form a thick interval between flat-bedded distributary-channel deposits. The rhythmic beds are interpreted as levee and interdiatributary-bay sediments that were deposited under seasonally fluctuating discharge. The complexity of these successions results from a combination of channel shifting and from increasingly distal position during ice retreat. In the Okanagan section, a deep sedimentation basin and coarse deposits resulted in development of a prograding Gilbert-type delta with steep foresets.
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Glaciofluvial and Glaciolacustrine Sedimentation
This publication is the outgrowth of a symposium on Glacial Sedimentology that was held in Buffalo, New York, March 1972. The great interest generated in glacial phenomena during the nineteenth century had important implications and repercussions for the infant field of sedimentology. It provided its fair share of the background stimulus necessary to establish sedimentology as a separate branch of the earth sciences in the twentieth century. The time for reciprocity is now at hand; feedback from the expertise gained in the burgeoning field of sedimentology can greatly help the Quaternary specialist solve particular field problems. The last decade has witnessed a growing interest in the sedimentology of the Quaternary, and it seems appropriate now to summarize progress in the study of stratified drift, to present results of some recent studies, and to focus attention on avenues of research that should be explored in the near future.