Illinoian to late Wisconsinan stratigraphy at Woodbridge, Ontario

Near Woodbridge, northwest of Toronto, Ontario, a 15 metre-high railroad cut and associated borrow pit, first excavated in 1962, exposed a multiple till sequence and intervening fossiliferous sediments. Work over the next 35 years revealed that Illinoian York Till, early Wisconsinan Sunnybrook Till, and late Wisconsinan Humber till, Halton Till, and Wildfield Till are interbedded with fossiliferous sediments equivalent to the Sangamonian Don Formation, early Wisconsinan Scarborough Formation (>50 ka BP), and middle Wisconsinan Thorncliffe Formation (45 ka BP). A complex periglacial record displays multistage fossil frost wedges, indicating intervals of severe climate in late Illinoian and early Wisconsinan time. Cored boreholes indicate deep gravel below and a till on Ordovician shale bedrock (Georgian Bay Formation). Vertebrates, molluscs, ostracodes, insects, and plants (diatoms, wood, seeds, pollen) indicate mostly cool conditions (boreal to tundra) for interstadial sediments. Interglacial conditions are represented by vertebrates, molluscs, and plants above York Till. Many taxa are new to the Quaternary of the Toronto area.