Amino acid and other studies have been made on the 30-km Pleistocene sections of the Intracoastal Waterway between Myrtle Beach and Little River, South Carolina. Our ratios differentiate the long-established Waccamaw (oldest), Canepatch, and Socastee formations. The ratios from the four laboratories that have worked in this area agree very well, and apparent conflicts with U-series dates may merely reflect an abundance of reworked corals. Our amino acid correlations with U-series coral dates in South Carolina, Bermuda, and the Mediterranean all argue that the classical Canepatch and its Horry Clay date from isotope stage 5e and not, as has been implied, from stage 7, 9, 11, or 13. Excavations and erosion have increased position-fixing problems along the Waterway, and “Canepatch” amino acid ratios and U-series dates (460,000 ± 100,000 yr B.P.) at “ICW5” may be from an older unit. The Canepatch shows the double marine transgression visible in many stage 5e deposits. Pollen shows that the second transgression occurred late in the interglaciation, and stratigraphic studies show that it reached 14 m. It therefore fits very well Antarctic ice-surge models of stage 5 sea level and climate. The Socastee adds to the evidence for one or more sea levels above 0 m late in stage 5.

In an area north of the Giants Range in northeastern Minnesota the late Wisconsin glacial and extraglacial lithostratigraphy shows that, apart from one occurrence of red clayey till, the deposits can be related to the deglaciation of the Rainy Lobe, the margin of which retreated northward, leaving debris-rich ice behind. By a combination of pollen stratigraphy, lithostratigraphy, and chronostratigraphy of lake sediments in this area, together with multivariate numerical analyses of the data set, a “hiatus” stratigraphy was set up. Combined with the glacial and extraglacial stratigraphy, it shows that the area of Glacial Lake Norwood was possibly later filled with sediments, between masses of stagnant ice, following a damming of drainge in the south by the St. Louis Sublobe. The area was drained through the Embarrass channel when the St. Louis Sublobe retreated. Then followed the drainage of Lake Koochiching through the Embarrass channel. At ca. 10,200 14C yr B.P. the area apparently became free of stagnant ice as normal lake sedimentation began in all lakes studied. A lake-level rise is indicated ca. 1000 yr later. Apart from a long-lasting phase of birch tundra parkland between ca. 12,000 (or 11,500?) and 10,600 14C yr B.P., the general pollen stratigraphy fits into the regional picture with a more or less undisturbed and gradual plant immigration from the time of the culmination of the St. Louis Sublobe.

A lava flow in southern New Mexico extends into the Rio Grande Valley from the lower La Mesa geomorphic surface, a relict basin floor of middle Pleistocene age. Three buried soils occur beneath the lava at its east end. In places, the lava itself is buried by a sediment in which a soil has formed. Pedogenic carbonate was used to calculate the age of this soil, using a soil of lower La Mesa as a chronological guide. Both the latter soil and the Rio Grande Valley must be less than about 620,000 yr old according to dated volcanic ash, and are estimated to be about 500,000 yr old. Based upon this age and a total of 1200 kg/m2 pedogenic carbonate in the lower La Mesa soil, the carbonate accumulated at an average rate of about 2.4 kg/m2/1000 yr. Using the same rate of carbonate accumulation, the postlava soil took about 180,000 yr to form. However, not quite all of the pedogenic carbonate in this soil has been accounted for, and a general figure of 200,000 yr is suggested for its approximate age. The geological setting indicates that the age of the lava should be very close to the age of the postlava soil, and a general figure of 200,000 yr is also suggested for approximate age of the lava. This contrasts with a new K/Ar age of 490,000 ± 30,000 yr, which is considered to be too old. However, two previously obtained K/Ar ages of 232,000 ± 80,000 and 154,000 ± 119,000 yr are much closer to the estimate based on pedogenic carbonate. The landscape of the soil that buries the lava differs from the landscape of the lower La Mesa soil that was used as a chronological guide. The rate of carbonate movement into the soils could also differ, and for this reason the age obtained by pedogenic carbonate is considered tentative.

Sediment features and soil patterns indicate that permafrost developed beyond the late Wisconsinan (Woodfordian) ice margin in Illinois. Vertical wedge-shaped bodies in Woodfordian glacigenic deposits and buried by Woodfordian loess are interpreted to be ice-wedge casts. Large-scale patterned ground, common on the late Wisconsinan drift plain and on the Illinoian drift plain to the south and west, also is interpreted to be the result of ice-wedge formation. Permafrost extended to about 38° 30′ N latitude and formed during the interval from about 21,000 to 16,000 yr B.P. Formation and degradation of permafrost was time-transgressive, directly related to the ice-marginal climate, and probably restricted temporally to less than 1000 years at a site. The following environmental conditions are suggested near the ice margin: mean annual ground temperature −3°C; mean annual air temperature −6 ± 2°C; less precipitation than modern, particularly in winter; strong and likely dry wind systems; and relatively open vegetation with few woody plants.

Postglacial geomorphic development of the Buchanan Drainage, a small tributary to the South Skunk River, is reconstructed by documenting relationships among four allostratigraphic units and 17 radiocarbon dates. Formation and headward expansion of the valley was both episodic and time-transgressive. Response to downstream conditions in the South Skunk River largely controlled the early formation of the basin. Downcutting through Pleistocene deposits produced a gravelly lag deposit that was buried by alluvium in the downstream portion of the valley during the early Holocene (10,500–7700 yr B.P.). Lag deposits formed in a similar manner continued to develop in the upper portion of the drainageway into the late Holocene (3000-2000 yr B.P.). Episodes of aggradation during the middle Holocene (7700-6300 yr B.P.) and late Holocene (3000-2000 yr B.P.) were separated by a period of soil formation. Holocene geomorphic events in the drainageway coincide with some vegetational and climatic changes as documented in upland pollen sequences from central Iowa. Analysis of plant macrofossil assemblages recovered from alluvium indicates that during the middle Holocene forest contracted and prairie expanded into the uplands within the basin. Vegetational changes within the basin apparently had only minor influence on rates of hillslope erosion, and the widely accepted relationship between prairie (versus forest) vegetative cover and increased rates of hillslope erosion did not hold. Instead, greater amounts of erosion occurred under forested conditions when local water tables were higher and seepage erosion was more effective.

Fission-track ages of zircon crystals from four tuff layers in the late Cenozoic sediment sequence of the Boso Peninsula,.Japan, are 1.6 ± 0.2 myr (the Kurotaki Formation), 5.5 ± 0.6 and 5.2 ± 0.5 myr (the uppermost part of the Amatsu Formation), and 11.5 ± 0.8 myr (the middle part of the Amatsu Formation). These ages provide numerical age constraints on magneto-biostratigraphy. The normal polarity interval in the lower part of the Kiwada Formation corresponds to the Olduvai polarity subzone. The boundary between the Pliocene and Pleistocene lies slightly above the Olduvai polarity subzone.

Fine-grained excavation and analysis of a stratigraphic column from Danger Cave, northeastern Great Basin, suggests prehistoric hunter-gatherers were collecting and using singleleaf pinyon (Pinus monophylla) near the site for at least the last 7500 yr. Human use of the cave began after the retreat of Lake Bonneville from the Gilbert level, shortly before 10,000 yr B.P. In stratum 9, culturally deposited pine nut hulls appear in the sequence by about 7900 yr B.P. and are continuously present thereafter. A hull fragment in stratum 10 is directly dated to 7410 ± 120 yr B.P. These dates are at least 2000 yr earlier than expected by extrapolation to macrofossil records from the east-central and central Great Basin, and necessitate some revision of current biogeographical models of late Quaternary pinyon migration.

A fossil pecan, Carya illinoensis (Wang.) K. Koch, from floodplain sediments of the Mississippi River near Muscatine, Iowa, was accelerator-dated at 7280 ± 120 yr B.P. This discovery indicates that pecan was at or near its present northern limit by that time. Carya pollen profiles from the Mississippi River Trench indicate that hickory pollen percentages were much higher in the valley than at upland locations during the early Holocene. Pecan, the hickory with the most restricted riparian habitat, is the likely candidate for producing these peaks in Carya pollen percentages. Therefore, pecan may have reached its northern limit as early as 10,300 yr B.P. Its abundance in Early Archaic archaeological sites and the co-occurrence of early Holocene Carya pollen peaks with the arrival of the Dalton artifact complex in the Upper Mississippi Valley suggest that humans may have played a role in the early dispersal of pecan.

The first pollen and phytolith data covering the entire Pleistocene/Holocene transition from the lowlands of the Central American isthmus indicate that the forests of late-glacial Panama at an altitude of 650 m resembled those currently found at ca. 1500–1800 m. A temperature depression of ca. 5°C and reduced precipitation/evaporation ratios in the late-glacial period are suggested. Forest composition from ca. 14,000 to 10,500 yr B.P., although primarily montane in character, contained a low biomass of species today segregated in lowland forests and, hence, a floral assemblage with no modern analog. The sudden appearance of carbon and burnt, weedy plant material at ca. 11,000 yr B.P. is attributed to the earliest human impact yet recorded from tropical America and may perhaps have been associated with the first human occupation of the region.

Oxygen isotope determinations on the α-cellulose of tree rings cut from two leaning Picea engelmannii revealed significant differences between results from normal and compression wood radii. Nine samples (10-year periods) from the normal wood radius (1721–1953) in one tree showed good agreement with proxy climate information and maximum differences of 1.8‰ between the “warmest” and “coolest” decades sampled. Differences of equivalent magnitude were found between samples from the same decade from normal and compression wood radii. These differences are strongly related to the amount and/or density of compression wood present and suggest that sampling for paleoclimatic work should be restricted to complacent, erect trees without compression wood rings.

Fossil insects from the late-glacial deposits at the Lamb Spring archaeological site, near Denver, Colorado, are relatively abundant and diverse, providing considerable paleoecological data for the site. The late Pleistocene insect fauna from the site comprises 72 identified taxa, principally beetles. However, the fauna presented an interpretive problem because it contained a mixture of prairie and alpine tundra species. This was initially considered to be the result of a mixing of faunal elements during the climatic transition of late-glacial times, a “no-modern-analog” fauna. Accelerator dating of insect fossil specimens from the two ecological groups helped resolve the paleoecological problem. Fossil specimens of the prairie-associated species were dated at 17,850 ± 550 yr B.P., while specimens of the tundra-associated species yielded an age of 14,500 ± 500 yr B.P. These dates reveal that what appeared to be an ecological mixing was probably a taphonomic problem, wherein full-glacial-age fossils were probably reworked into latest Wisconsin sediments. While both faunal assemblages reflect climatic conditions substantially colder than present, initial results suggest that the full-glacial fauna represents a cold, dry grassland or steppe environment, while the younger fauna suggests moister and more tundra-like conditions.