Isabelle Therriault HBSc thesis abstract

Thesis Title: 
Geochemical Investigation of Lake Sediment Cores and Soil Samples from Whitefish Lake, Ontario: Characteristics and Geoarchaeological Implications

Many generations and cultures have traveled the waters and harvested the resources of Whitefish Lake, a shallow boreal lake located in northwestern Ontario.  Archaeological reconnaissance and excavations in the 1960s and 1970s uncovered the importance of the site, but could not completely unravel its mysteries.  Within the framework of a multiproxy and multidisciplinary approach, this contribution sheds light on the environment evolution of Whitefish Lake, by investigating the geochemistry of lake sediment cores and soil samples collected on and around MacGillvray Island.

At the onset of the Holocene, Whitefish Lake first existed as a multi-stage proglacial lake fed by melting ice sheets in which laminated sediments were deposited.  Climatic fluctuations during the Holocene brought varying humidity and temperature combinations, with subaerial exposure of lake bottoms during drought cycles.  With the return of cooler and moister conditions, the lake basin filled to present-day levels.  Nowadays, macrophyte beds abound on the fringes of the lake and contribute to the formation of reducing conditions below the sediment-water interface.  Sedimentation levels are very low, with sediments comprised of material derived from authigenic and allogenic organic matter as well as from erosion in the catchment area.

The archaeological record reveals that humans have occupied the Whitefish landscape for a long period of time.  However, their arrival could not be constrained geochemically with the presently available data set because the weak signal is overprinted by variations in climatic and environmental conditions.