Radiocarbon dates of plant materials from packrat middens in caves below the elevation of the last high stand of Pleistocene Lake Lahontan, in conjunction with radiocarbon dates of ancient archaeological materials, provide evidence that the last high stand terminated before 12,070 yr B.P. This new information suggests that the last major fluctuation in the level of Lake Lahontan was approximately synchronous with those of Lakes Bonneville and Russell, and that these three lakes probably responded contemporaneously to the same regional paleoclimatic changes.

Historical observations of fjord glaciers in southern Alaska suggest that their fluctuations may be asynchronous with one another and with climate. Possible causes for anomalous fjord glacier response to climatic changes involve the instabilities inherent in a calving terminus, the interaction of fjord geometry with the extent of the calving terminus, and the intersection of low-lying snow line by a thickening glacier. The Lituya glacier system in southeast Alaska is analyzed with reference to these phenomena to test the reliability of its Holocene glacial deposits as paleoclimatic records. This fjord glacier is shown to have been probably free of major, nonclimatic responses during the Holocene except for an insensitive period of up to 1000 yr that followed calving retreats. The insensitive period has no functional effect on how the relatively coarse geologic record is interpreted in terms of paleoclimate. However, it makes impossible any inference of climatic trends from this glacier's behavior in historical times. Fjord glacier deposits can be dependable records of paleoclimate but each glacier requires careful scrutiny. Anomalous glacier responses to climate are most likely to occur in fjords of complex geometry, in regions of relatively low snow line, and where glaciers terminate at fjord mouths bordering the open sea.

The sequence of glacial deposits near McCall, Idaho, previously assigned to the Pinedale and Bull Lake glaciations, contains deposits of four different ages. These ages are defined by multiple relative-age criteria, including weathering rinds, soil development, surface-rock weathering, morainal morphology, and loess stratigraphy. The thickness of weathering rinds on basaltic clasts is statistically representative and reproducible and can be used to estimate numerical ages. Following in order of decreasing relation to age are soil development, surface-rock weathering, and moraine morphology. The glacial deposits near McCall appear to correspond to times of high worldwide ice volume indicated by the marine oxygen-isotope record. Pilgrim Cove and McCall deposits, both assigned to the Pinedale glaciation, are late Wisconsin in age, perhaps 14,000 and 20,000 years, respectively. They represent a rare case in which deposits of Pinedale age can be separated by relative-age data. Timber Ridge deposits, assigned to the Bull Lake glaciation, have subdued, but well-preserved morainal morphology; relative-age data indicate that they are pre-Wisconsin in age, probably about 140,000–150,000 years old, although we cannot exclude an older age. Williams Creek deposits are clearly distinct from, and intermediate in age between, McCall and Timber Ridge deposits. Weathering rinds and the inferred ages of the other deposits suggest an early Wisconsin age for Williams Creek deposits.

Glacial Lake Devlin was an ice-margin lake that formed during Pinedale time when the North Boulder Creek valley glacier blocked the mouth of a tributary near the downvalley limit of glaciation. The lake was about 2 km long and as much as 60 m deep, and was fed by meltwater from small valley glaciers. It accumulated sediment, apparently without interruption, for about 10,000 yr. The inception of Lake Devlin between 23,500 and 21,000 yr B.P. provides a limiting date for the maximum expansion of Pinedale ice, because the lake could not form until the North Boulder Creek glacier had advanced to within 2 km of its downvalley limit. The maximum lowering of timberline, which occurred about 19,000 yr B.P., is assumed to coincide with the Pinedale glacial maximum. Apparent timberline elevations determined from Picea/Pinus pollen ratios suggest that ice-front positions during the time between 23,000 and 19,000 yr B.P. may have been only slightly less extensive than at the Pinedale maximum. Lake Devlin drained catastrophically about 13,000 yr B.P., which was after ice had receded from the outlet area. Pinedale glaciation in the Front Range began about or after 30,000 yr B.P. and final deglaciation occurred between 15,000 and 12,000 yr B.P.

The 104 available [230Th/234U] analyses of unrecrystallized corals from stable emerged terraces indicate that the last interglacial period occurred approximately 125,000 yr ago. An estimate is made of the exact duration of this period by accounting for the surprisingly small distribution width observed among the 80 most reliable analyses. This distribution width is compared with those obtained for model populations generated by assuming various characteristic analytical errors and various lengths of the last interglacial period. The results show that (1) if there was only a single rise in sea level, it probably lasted no more than 12,000 yr, in agreement with previous estimates; and (2) if there were two separate rises of sea level, the gap between them must have been less than 7500 yr and not 12,200 as proposed by some authors.

The isotopic composition of paleosol carbonates from Olduvai Gorge can be used to give estimates of the paleoclimatic history of East Africa during the Plio-Pleistocene. Oxygen isotopes are indicative of major changes in the isotopic composition of meteoric water, while carbon isotopes are indicative of major changes in the fraction of biomass using the Hatch-Slack (C4) photosynthetic pathway. Three major periods of climatic change in this terrestrial setting occurred at about 1.67, 1.3, and 0.6 myr. These involved major changes in flora as well as major changes in the isotopic composition of meteoric water. Overall, the climate has become warmer and more arid over the past 2.2 myr.

Under the near-ideal hydrologic conditions provided by the Uitenhage artesian aquifer, reliable estimates of paleotemperatures were obtained by measurement of the dissolved N2 and Ar in groundwater, confidently dated in the range 28,000 yr B.P. to the present using 14C. The mean annual air temperature in this area during the last glaciation is calculated to have been, on average, 1/2°C lower than during the Holocene. The change in the 18O/16O ratio of the groundwater, corrected for changes in ocean water, amounted to 0.4‰ per °C.

An investigation of Illinoian- and Sangamonian-age deposits in the type region for both Pleistocene stages in central Illinois has yielded a palynological record spanning the Illinoian-year during at least the portion of the Sangamonian represented. Sangamonian boundary associated with an interglacial fauna containing Geochelone crassiscutata. The pollen indicates a shift from high Picea and Pinus to deciduous trees, followed by grass and herbaceous taxa, and finally, a return of deciduous trees. This sequence appears to correlate with marine isotopic stages 6 through 5d. Faunal remains are abundant throughout but megafauna are present only in the interglacial section where Geochelone occurs. The presence of Geochelone suggests above-freezing temperatures in central Ilinois throughout the

Seventy surface pollen samples from coastal forest, coastal meadow, muskeg, tree line, and alpine tundra communities form a basis for interpreting fossil pollen assemblages in the Malaspina Glacier district, Alaska. Poflen and macrofossil analyses of three radiocarbon-dated fossil sections from Icy Cape indicate that vegetational changes resulting from plant succession can be distinguished from those of migrational and climatic origin. Vegetation of the early Holocene xerothermic interval (10,000–7600 yr B.P.) was dominated by Alnus communities. Wetter conditions ensued, enabling generative muskeg surfaces to develop and first Picea sitchensis, then Tsuga heterophylla to expand from areas southeastward. Climatic cooling in more recent millennia (3500 yr B.P. to the present) is indicated by the appearance and persistent growth of Tsuga mertensiana and Selaginella selaginoides along this portion of the Gulf of Alaska coastline.

The discovery of a unique organic deposit in a dry cave on the Colorado Plateau, southern Utah, permits the first comparison of the physical characteristics and the diet of the dung of the extinct mammoths from the arid Southwest, North America, with that of mammoths from Siberia and northern China, the only other known locations of such remains. The deposit buried beneath sand and rockfall is composed primarily of mammoth dung, estimated at over 300 m3. Radiocarbon dates on dung boluses indicate that the mammoths frequented the cave between approximately 14,700 and 11,000 yr B.P. (the range of ages at 2σ). The desiccated boluses, measuring approximately 230 × 170 × 85 mm, are nearly identical in size to dung from extant elephants. The largest contents in the dung are stalks measuring 60 × 4.5 mm. Grasses and sedges dominated the diet, although woody species were commonly eaten.

Megaloceros giganteus, the largest Eurasian deer, inhabited Ireland from ca. 12,000 yr B.P. to the time of its extinction ca. 10,600 yr B.P. The archaeologic record documents that people arrived on the island no earlier than 9000 yr B.P., so they could not have caused the extinction in Ireland. Close stratigraphic association of the geologically youngest elk fossils with sediments indicating the onset of the Nahanagan Stadial (approximately = Younger Dryas) implicates climatic change as the exterminator. Palynologic data support the idea that extinction probably resulted when forage quantity and quality along with length of the spring green-up decreased during the Nahanagan Stadial. For M. giganteus, this meant that the energy intake required to sustain large bodies, grow enormous antlers, and build fat reserves for winter was increasingly difficult to maintain, until deaths, primarily by winterkill, outnumbered births.