Figure 2. Idealized distribution of palynoflora from hinterland, through tranisitional and into marine paleoenvironments. Upland paleoenvironments are dominated by terrestrial palynoflora: bisaccate pollen, pteridophyte spores (e.g. trilete spores) and freshwater lacustrine algae (e.g. Pediastrum). Low-salinity dinoflagellates (e.g. Vesperopsis, Pseudoceratium) represent the landward encroachment of marine (tidal) waters, and marine dinoflagellates (e.g. Palaeoperidinium, and other cosmopolitan forms) are abundant in offshore, neritic paleoenvironments and deeper. Distribution and relative percentages of these palynofloral groups within these paleoenvironments may be altered by factors such as climate, increased fluvial activity, and changes in sea-level. Paleoenvironments with low-salinity dinoflagellates are those envisaged for much of the deposition of the McMurray Formation at Surmont. Diagram modified from Michoux (2002).