A postglacial plant macrofossil record of vegetation and
climate change in southern Saskatchewan
Catherine Yansa and J.F. Basinger
The Andrews site is a small closed-drainage
basin on the Missouri Coteau of southern Saskatchewan that has been filled
with postglacial sediment. Plant macrofossil analyses of 67 sediment
samples and 6 14C ages were used to reconstruct 6 phases of environmental
changes that followed deglaciation in southern Saskatchewan. Fossil
remains of 42 taxa of vascular plants have been recognized and are illustrated. Sparse macrofossils recovered from
the basal diamicton (Phase 1) are likely redeposited. Abundant fossils
indicate establishment of an open white spruce forest by ca. 10.2 ka BP (Phase
2), followed by development of a pond and replacement of the spruce forest
by deciduous parkland vegetation (Phase 3) that persisted until ca. 8.8 ka
BP. The pond shallowed at the end of this period. Prairie fires
are evident between ca. 8.8 and 7.7 ka BP (Phase 4). Water levels rose
between ca. 7.7 and 5.8 ka BP and a semi-permanent prairie pond was established
(Phase 5). After 5.8 ka BP this wetland became ephemeral (Phase 6)
and no longer conducive for fossil preservation.