Abstract

Fine fraction analysis of matrix samples from Cody-complex levels of the Fletcher site (DjOw-1) has yielded abundant macroremains including seeds, plant fragments, mollusc shells, bird's egg-shell, insects, ostracodes, and faunal remains, dated around 9,300 yr. BP. Identified seeds include those from aquatic (Potamogeton, Zannichellia palustris) and wetland (Scirpus) taxa that suggest the presence of permanent, if somewhat brackish, water. At present, the area has few sources of permanent water on upland surfaces, especially in mid-summer. Other identified macroremains include Scirpus validus/autus, Ranunculus sceleratus, Ceratophyllum demersum, Hippuris vulgaris, Boraginaceae, Chenopodium spp., Graminae, Polygonum, Cyperaceae undiff., Typha latifolia seeds, and Rumex periaths. Molluscs include the aquatic taxa: Gyrsaulus spp., Promenetus exacuous, Armiger crista, Lymnaeidae, Physa, Pisidium, and Helisoma. The assemblage also includes a few specimens from land snails (Vallonia, Succinea, and Vertigo). Above the Cody-complex levels, there is a transition to clastic (windblown?) sediment which is essentially sterile. This sediment infilled the wetland hollow. The Fletcher site record is one of a series of new palaeoenvironmental records that also includes the Jenner and Weber Dugouts (constructed for cattle watering) in Southeastern Alberta. These sites have yielded wood, including aspen, dated between 10,150 and 9,800 yr. BP. Together, these three records are providing a more complete picture of early postglacial landscapes (ca. 11,000-9,000 yr. BP) in southern Alberta and indicate considerable differences from present landscapes. In particular, they suggest that early postglacial landscapes were well-watered, despite indications of climatic aridity from elsewhere. Water may have been derived from melting residual ice and permafrost contributions to groundwater. The Fletcher site shows that there may have been more (fresher) water sources on the Canadian Plains in the early postglacial than at any time since. Perennial water and productive wetlands may have been attractive for human occupants, especially in summer. This suggests that Paleoindian occupation patterns and land-use on the Canadian Plains may be quite different to those of later occupants.