Late Quaternary history and paleoecology of a small oxbow wetland on glaciated terrain were investigated using sediment lithology (cores, bulk samples, backhoedug trenches), ground-penetrating radar, vascular plant and moss macrofossil stratigraphies, and accelerator mass spectrometric radiocarbon dating. A nearly complete mastodon skeleton was recovered from late Pleistocene detrital peat and peaty marl near the top of the sediment sequence. Sedimentation in the basin began with silt and clay over dense cobble outwash transported southward from the nearby Hyde Park Moraine. Overbank sediment deposition occurred between ∼13,000 and 12,220 yr B.P. during a period of tundra vegetation, which ended with a sharp rise in spruce needle abundance and a shift to autochthonous marl and finally peat deposition. Fossils of aquatic and wetland plants began to accumulate before the tundra-spruce transition and increased after it. Rich fen wetland began to infill the pond with peat, while the upland supported open white spruce and later white spruce–balsam fir–tamarack forest. The mastodon, 11,480 ± 40 radiocarbon years old, was contemporaneous with spruce–balsam fir–tamarack forest and rich fen wetland. Many mastodon bones were articulated or nearly so, indicating that the animal died in the basin and that postmortem bone dispersal was slight.

Study of plant remains found intercalated between two till bodies in Cheboygan County at the northern tip of the Southern Peninsula of Michigan suggests that an open vegetation, floristically similar to a dwarf-shrub tundra or tundra communities within the tundra-boreal forest ecotone was present in this area sometime between 12,500 and 13,300 years B.P. The organic layer that has been correlated with the Cary–Port Huron (Lake Arkona) interstade consists mostly of bryophytes. Eight species of mosses; two kinds of leafy liverworts; achenes from Carex tenuiflora and/or C. trisperma; a perigynium of Carex supina; leaves of the arctic-alpine plants Dryas integrifolia, Salix herbacea, and Vaccinium uliginosum var. alpinum ; and Salix twigs have been identified from the deposit. Pollen analysis of the bryophyte bed and associated sediments yielded spectra dominated by nonarboreal pollen, but a significant amount of spruce pollen is also present. Evidence is given that indicates that some of the pollen is rebedded. The macrofossils suggest the presence of distinct communities on wet and dry sites.