Faults in glaciofluvial sediments are interpreted in the light of the experimental work of Sanford (1959). Internal displacements in the sedimentary sequence resulted from the melting of associated ice. Field examples are used to illustrate that (a) melting of a discrete buried ice mass will produce a downthrown block of sediment bounded by high-angle reverse faults that are convex upwards; (b) melting the ice walls that supported an esker of subglacial origin will result in high-angle reverse faults, concentrated in the flank of the esker, that strike parallel to the esker ridge and dip steeply in toward the esker axis; such walls probably were not vertical but, rather, dipped inward toward the esker axis; and (c) large normal faults may be related to deposition over a saucer-shaped ice base. Minor normal faults may complement high-angle reverse fault systems in (a) and (b). The scale, type, and distribution of faults, and the orientation of faults with respect to the sediment body and to paleocurrent directions can contribute to a reconstruction of the sedimentation environment. These data provide useful criteria for identification of fluvial sediments as glaciofluvial.
Figures & Tables
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.