Quaternary stratigraphic of the low Gods River region, Hudson Bay lowlands, Manitoba

Abstract

Four or more tills, commonly separated by nonglacial deposits, are exposed along the Gods River in northwestern Hudson Bay Lowland. The oldest till (Till A) overlies Paleozoic bedrock and is overlain by fossiliferous beds of fluvial, lacustrine, and organic origin (Gods River sediments). Pollen, spores, seeds, wood, insects, and molluscs from within the Gods River sediments record a subarctic climate and a vegetational succession that began and ended with tundra. During the warmest part of the interval, a forest-tundra vegetation grew in the region. The Gods River sediments are correlative with the Missinaibi Formation in northern Ontario and a Sangamon age is inferred. Till B, which overlies the Gods River sediments, is usually separated from the younger Till C by stratified sand and gravel devoid of organic material (Twin Creeks sediments) . This glacial-nonglacialglacial sequence probably encompasses the greater part of Wisconsin. time. The uppermost till (Till D) was laid down during a glacial advance prior to about 7, 600 years B. P. Tyrrell Sea invaded the area contemporaneously with, or shortly after, deglaciation. Isostatic rebound raised the land surface and sea-level receded rapidly. During the initial thousand-year period following inundation, the rate of uplift was about 6 m/ century. Since then, the rate of uplift has decreased to about O. 6 m/ century.