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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.

Amino acid epimeric (aIle/Ile) values from terrestrial molluscs are used to define and correlate three aminozones in loess sequences exposed across the central Mississippi Valley, in Arkansas and Tennessee. Three superposed aminozones are defined at Wittsburg quarry, Arkansas, primarily using aIle/Ile values from total hydrolysates of the gastropod genus Hendersonia: Peoria Loess (aIle/Ile = 0.07 ± 0.01), Roxana Silt (0.14 ± 0.02), and a third loess (0.28 ± 0.06). Loess units at Wittsburg quarry can be correlated on lithologic characteristics eastward across the Mississippi Valley to the Old River section, near Memphis, Tennessee; however, only one loess unit is fossil-bearing (Peoria Loess, aIle/Ile = 0.05) at that section. Radiocarbon analyses of charcoal from the upper Roxana Silt (ca. 26,000 to 29,000 yr old) and mollusc shell carbonate from the basal Roxana Silt (ca. 39,000 yr old) are used to calibrate amino acid epimeric data for the central Mississippi Valley. These data, applied to the apparent parabolic kinetic model of R. M. Mitterer and N. Kriausakul (1989, Quaternary Science Reviews 8, 353-357), suggest an Illinoian (>120,000 yr) age for the third loess in the central Mississippi Valley that is correlative with part of the Loveland Loess in Illinois and Iowa.

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A fossil assemblage containing molluscs, mammals, insects, ostracodes, and plants has been recovered from a silt-filled depression near Lima, in west-central Illinois. The reversed remanent magnetic signature of the sediments and the temporal ranges of two mammals, Microtus paroperarius and Lasiopodomys deceitensis, constrain the age of the assemblage to between 730,000 and 830,000 yr B.P. The extent of isoleucine epimerization in the molluscan shell is consistent with this age interpretation. The fauna includes at least 43 taxa of beetles from 11 families, 35 nominal species of molluscs, and two genera of ostracodes. The mammals include two shrews, three rodents, and a rabbit. The plant macrofossils (no pollen recovered) include 25 species of seed plants and four kinds of terrestrial or wetland mosses. Most of the plant species identified still occur in the upper Midwest, although a few of the taxa are found mainly to the north of the site. The fauna is characterized by an almost total absence of true aquatic taxa. The association of both boreal and thermophilous faunal and floral elements suggest that summer temperatures were not greatly different from present ones, but cooler, moist areas must have been available to support the boreal elements. Local conditions were probably similar to those now found in northeastern Iowa, where rains blocks, fissures, and joints in carbonate bedrock serve as traps for debris accumulations, provide shade, and are kept cool and moist during the hot summer months by cold-air drainage and groundwater seepage. Summer mean temperature in these microhabitats was probably between 18 and 20°C, similar to temperatures that now occur near the northern hardwood spruce-fir transition in the eastern United States.

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