Late Quaternary chronology and environments of Square Lake, Torngat Mountains, Labrador
Sediment, pollen, and diatom records from Square Lake, a small lake dammed by a segment of Saglek Moraine, cover the period of deposition of and deglaciation from the Saglek Moraine. The basal radiocarbon date (18 210 ± 1900 years BP) is on sediment contaminated by reworked pollen and is thus a maximum age. However, the date was measured on organic carbon recovered from glaciolacustrine couplets associated with deposition of the Saglek Moraine and thus establishes a Late Wisconsinan age for the Saglek Moraine. Vegetation on the ice-free upland surrounding Square Lake at this time was a sparse tundra vegetation dominated by grasses and herbs. The absence of diatoms indicates perennial lake-ice cover. A major transition is recorded by pollen and diatoms at > 8.5 ka. Vegetation probably remained sparse tundra, but birch and willow may have arrived in the area by 8 ka. Diatoms are first dominated by alkaliphil species, reflecting continued influence of glaciolacustrine sedimentation. An abrupt change in depos...