Surficial geology of Avalon peninsula, Newfoundland

In this report the physiography, climate, vegetation, and hydrogeology of the Avalon Peninsula and the immediately adjacent areas are outlined, the glacial and postglacial deposits described, and the glacial and postglacial history of the area developed. Although there were probably several Pleistocene glaciations, all the observed evidence is related to the Wisconsin. A separate, vigorous ice cap is considered to have formed over the Avalon early in the Wisconsin and its radial outflow dominated all the peninsula except the northern extremities, which had thin local coverings of their own. Ice flowing east from Newfoundland areas to the west of the Avalon was diverted northeast and southwest down Trinity and Placentia Bays and did not reach the Avalon proper, although it did cover the northern half of the Isthmus of Avalon. At the Wisconsin glacial maximum, large trunk glaciers from the Avalon cap flowed down the main bays, greatly overdeepening them in parts and depositing morainic banks on the ocean floor at their mouths. From the character and disposition of the glacial and glaciofluvial deposits and of glaciofluvial erosion features, it is possible to trace shifts of the ice centre and the mode of final ice retreat. Since retreat of the ice, differential uplift has raised the northwest corner of the area relative to the sea, but over the rest of the peninsula the isostatic rise of sea level has exceeded uplift and there has been postglacial coastal submergence. Relative stability of present sea level on the east coast is postulated until further data bearing on any anomalous modern rapid rise has been accumulated, if, indeed, such data exist. The cool, humid, postglacial climate has resulted in the azonal development of areas of patterned ground and has made possible the growth of extensive organic deposits. Radiocarbon dating of these deposits suggests deglaciation of the Avalon took place more than 10,000 years ago. Probable interglacial benches have been cut in sheltered positions along the Avalon eastern coast south of St. John's. They all appear to have the same age and show no tilt because they run parallel to postglacial uplift isobases. A tentative age of Sangamon maybe assigned to them. Benches cut elsewhere may not be correlated with the east-coast group. The economic potential of surficial deposits in the peninsula is outlined and discussed.