Abstract

Macrofabric studies and scanning electron microscopic (SEM) analysis of sand grains in Sunnybrook diamicton confirm that it consists of lodgment and/or deformation till. Formation of Sunnybrook drift included deposition of glaciolacustrine mud and grounding of early Wisconsin ice, followed by rainout of glaciolacustrine sediments. Macrofabric and quartz microtexture analyses support a model of deposition of the middle member (Sunnybrook diamicton, unit b) as lodgment and/or deformation till. Macrofabrics show generally bimodal, and occasionally trimodal, orientations that in the lower part of the unit indicate progressive change in direction of ice movements: first westward to northwestward, and latger (in the middle and top of the unit) to the northwest. Quartz-grain microtextures show extensive crushing effects compatible with deposition by grounded active ice, as determined at other continental locales including Antarctica, Fenno-Scandia, northern Ontario, and Wellsch Valley, Saskatchewan.

You do not currently have access to this article.