Late Quaternary Chronology for the Watts Bay Area, Frobisher Bay, Southern Baffin Island, N.W.T., Canada

Abstract

Maximum lichen diameter (Alectoria minuscula, Rhizocarpon geographicum), percentage lichen cover and depth of pitting on surface boulders were used to define a Holocene and late Pleistocene chronology for a Grinnell Ice Cap outlet glacier and a nearby cirque glacier in southernmost Baffin Island. Sites (32) were classified into 5 units of late Neoglacial (Units 1, 2, and 3), Cockburn-late Foxe (Unit 4) and pre-late Foxe (Unit 5) age. Discriminant analysis confirmed this classification. Moraines of Unit 1 were deposited very recently and are still unstable. Unit 2 and 3 moraines, which define the maximum late Neoglacial extent of glaciers in this area, were deposited less than 130 yr ago. Cockburn-late Foxe moraines (.apprx. 8000-11,000 yr B.P.) occur only a few tens of meters beyond the late Neoglacial maximum. Comparison with other records of Neoglacial fluctuations on Baffin Island shows that earlier Neoglacial activity is well documented to the north (e.g., Cumberland Peninsula, Barnes Ice Cap). The late Neoglacial moraines at the Watts Bay margin of the Grinnell Ice Cap, therefore, represent the youngest. Neoglacial maximum so far recorded in Baffin Island. The ice cap outlet glacier and cirque glacier studied reached their maximum. Neoglacial extent .apprx. 60 yr apart, perhaps due to a lag in the response of the ice cap to climatic change. An investigation of clast rounding as a relative dating parameter indicated that it should be applied with particular care to glacial deposits, because roundness is a function of environment of transport as well as time since deposition.