Deglaciation of the Pouch Cove area, Avalon Peninsula, Newfoundland: a palynological approach

Mellars, Gillian (1981) Deglaciation of the Pouch Cove area, Avalon Peninsula, Newfoundland: a palynological approach. Masters thesis, Memorial University of Newfoundland.

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Abstract

Recent studies (Ives 1978) have suggested that a re-evaluation of the earlier theories of the maximum extent of late-glacial ice in eastern Canada is necessary. The late-Wisconsinan glaciation of Newfoundland has been the subject of much speculation and debate but with recent field-work primarily centred along the west coast of the island and the Burin Peninsula. -- The maximum limit of the late-Wisconsinan ice on the Avalon Peninsula, Newfoundland, is uncertain. Divergent opinions have been expressed in the literature by Henderson (1972) and Grant (1977a) as to whether glacial ice covered the northern extremity of the St. John's Peninsula (Figure 1.1 p. 15). The objective of the research was to clarify its position by establishing a minimum date for deglaciation, absolute or relative. -- The geomorphology of the study area suggests that two recognizably different glacial landscapes exist north and south of Pouch Cove. Two subglacial tills are exposed by a quarry to the north of "Birch Hill's Pond". In the southeast of the study area a group of well defined meltwater channels suggest that meltwater drained eastward from an ice margin within a trough to the west. However the presently available evidence does not suggest whether or not these observations are a product of different glaciations or reflect the oscillations of an ice margin during the last glaciation. -- The lowest portions of three cores, one from "Birch Hill's Pond" and two from Northeast Pond., were subjected to palynological analysis and the basal organic sediments were submitted for radiocarbon dating. The pollen assemblages indicate changes in the regional vegetation during the early Holocene. Initial assemblages (8500 BP) suggest a shrub-sedge tundra vegetation which gave to a shrub tundra by 8300 BP, succeed in turn by boreal woodland similar in composition to that found in the area today. None of the basal pollen assemblages resemble the spectra collected by Pennington (1977) from recently deglaciated terrain, or a basal assemblage dated 9270 BP from near St. John's (Lowdon and Blake 1978; Macpherson 1980). The basal dates recorded in this study are therefore minimum dates for deglaciation, and appear too young to date ice retreat. -- Evidence from glacial landforms and till analysis is also inconclusive. The results of this study neither confirm nor refute the "maximum" glacial hypothesis of Henderson (1972) or the "minimum" glacial hypothesis of Grant (1977a). It may be stated with certainty, however, that the northern extremity of the St. John's Peninsula was free of glacial ice some time before 8500 BP.

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