ABSTRACT: Bison, birds, and bulrushes: early Holocene macroremains at the Fletcher site (DjOw-1), Alberta, and implications for plains landscape and climate.

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Abstract

Fine-fraction analysis of matrix material from the Cody-complex level at the Fletcher site (DjOw-1), southern Alberta, is yielding a detailed picture of the flora and fauna in and around a prairie surface lake around 9,000 years ago. Abundant bison remains are found in clay matrix at ca. 220-270 cm BD, overlain by predominantly sandy sediment. Plant macro-remains, mainly seeds, from wetland and aquatic plants (such as Scirpus, Zannichellia palustris, Potamogeton), indicate perennial water, rather than a seasonal slough. Gradual lake drying is shown by changing assemblages before transition to overlying sands. Vertebrate remains include larger fauna, such as Castor canadensis and Odocoileus indicating woody or shrubby vegetation in the vicinity, and small fauna including Microtus, Peromyscus, and Ambystoma tigrinum. Many samples contain fragments of bird's eggshell; morphological characteristics suggest that several bird taxa are represented. Several sampling and processing strategies are being used to explore variability within and between levels because, unlike pollen analysis, few published studies examine this. Replicate sample analysis shows considerable variability in the assemblages within the same level, between quandrants of the 2 x 2 m unit, and between levels. This may reflect differing positional characteristics (e.g., distance from shore) and inherent sample variability. Macroremains at Fletcher and other similar sites indicate that the plains surface probably had more permanent water sources in the early Holocene than at any time since. This does not necessarily argue for a wetter climate; water in these sites may have been derived from groundwater and meltwater during and after deglaciation. Once these locales had dried up in the early Holocene, precipitation has not been sufficient, even in the wetter Little Ice Age, to allow lakes to reform.

Bibliography of Canadian Geomorphology