Quaternary stratigraphy of the Severn and Winisk drainage basins, northern Ontario

Quaternary sediments outcropping in the Severn and Winisk drainage basins of northern Ontario include postglacial sediments, five till units, and interstadial deposits. Shagamu Till, the oldest unit, is attributed to southeastward ice flow on the basis of the abundance in this sediment of Devonian red carbonate erratics derived from central Hudson Bay. Rocksand Till is slightly enriched in Proterozoic erratics derived from the east is correlated to the Bell Sea of substage 5e. Sachigo Till, considered the deposits of ice sheet growth, yielded directional data indicating westward flow at its base and later southeastward flow implied by red carbonates. Severn Till is attributed to Late Wisconsinan southwestward ice flow on the basis of enrichment in Paleozoic debris, northeast-southwest pebble fabrics, striated boulder pavements, the younger striations at Big Trout Lake, and flutes in the Severn River area. -from Authors