A chronology for the Last Glacial Maximum based on cosmogenic exposure dati
ng in the Pangnirtung Fjord area, eastern Baffin bland, Arctic Canada, is a
t adds with many decades of land-based, glacial stratigraphic research. Mos
t previous chronologies focused primarily an relative weathering criteria a
nd suggested that ice extent was restricted during the late Wisconsinan (ca
. 24-8 ka). In contrast, by directly dating glacial features, we conclude t
hat late Wisconsinan ice was far more extensive than previously believed.
There are 36 gneissic boulders and 8 samples of ice-molded gneissic bedrock
that yield late Wisconsinan Be-10 and Al-26 exposure ages for the last gla
ciation of Pangnirtung Fjord. The prominent Duval moraines, which were prev
iously interpreted to represent a significant early Wisconsinan (100-60 ka)
ice advance on southern Cumberland Peninsula, were actually deposited betw
een 24 and 9 ka. Two boulders from a raised glaciomarine delta, stratigraph
ically related to the Duval moraines, date to about 10 ka. Two recessional
moraines and striated bedrock along Pangnirtung Fjord, as well as erratics
on the floor of the Kolik River valley, a tributary to Pangnirtung Fjord, i
ndicate that deglaciation began between 12 and 9 ka.
In situ produced Be-10 and Al-26 abundances indicate that ice filled Pangni
rtung Fjord for about 15 k.y. (either continuously or intermittently) prior
to 10 ka, which is compatible with C-14 chronologies for adjacent Cumberla
nd Sound. Thus, our data support other recent studies that suggest the nort
hern and southern margins of the Laurentide ice sheet were generally in pha
se during the latest Wisconsinan, contrary to earlier interpretations.