Reconstructions of Plio-Pleistocene habitats and lake levels from a brief interval (∼200,000 yr) of hominid-bearing sediments from Bed I and lower Bed II, Olduvai Gorge, Tanzania, are for the first time integrated with climatic data from the deep-sea in order to examine the effect of largescale climatic events in East Africa. The period of densely vegetated habitats and wet conditions at Olduval at ∼1.82 myr shows a best fit with a period of northern hemisphere warming as evidenced by oxygen isotopes from deep-sea core V28-239 from the western Pacific. This environmental response is similar to that witnessed in East Africa during the period of warming climates associated with deglaciation at ∼10,000–8,000 yr.

Annual pollen deposition (pollen cm−2 yr−1) was sampled for 6 yr in the southern Sierra Nevada, the Owens Valley, and the Inyo Mountains of central California. Spatial pollen distributions were examined for anemophilous plants which are limited to growth sites (1) at high elevations on one or both mountain ranges, (2) on lower mountain slopes, and (3) on the Owens Valley floor, Pollen deposition values for high- and low-elevation plants changed by a factor of 5 to 10 between adjacent sample sites which straddle boundaries of the plant communities in which the source plants grow. Pollen deposition values were high and variable within communities in which the species grew. Pollen deposition beyond source populations was low and uniform despite great differences in distance of sites from pollen sources. The step function that seems to characterize pollen distribution patterns implies that pollen from distant populations may be of little value in interpreting vegetation stability and change reflected by fossil pollen stratigraphy. The physical isolation of pollen embedded in the local mountain-valley wind system from that in the prevailing westerlies may explain part of the spatial distribution of the pollen.

Latest Pleistocene-Holocene basaltic lava fields of the Snake River Plain, Idaho, have been dated by the radiocarbon method. Backhoe excavations beneath lava flows typically yielded carbon-bearing, charred eolian sediment. This material provided most of the samples for this study; the sediment typically contains less than 0.2% carbon. Charcoal fragments were obtained from tree molds but only from a few backhoe excavations. Contamination of the charred sediments and charcoal by younger carbon components is extensive; the effects of contamination were mitigated but appropriate pretreatment of samples using acid and alkali leaches. Twenty of the more than 60 lava flows of the Craters of the Moon lava field have been dated; their ages range from about 15,000 to about 2000 yr B.P. The ages permit assignment of the flows to eight distinct eruptive periods with an average recurrence interval of about 2000 yr. The seven other latest Pleistocene-Holocene lava fields were all emplaced in short eruptive bursts. Their 14C ages (yr B.P.) are: Kings Bowl (2222± 100), Wapi (2270 ± 50), Hells Half Acre (5200 ± 150), Shoshone (10,130 ± 350), North Robbers and South Robbers (11.980 ± 300), and Cerro Grande (13,380 ± 350).

The recent discovery of a post-Roman-aged marine calcarenite terrace, at an altitude of 7 to 8 m at the ancient harbor of Akhziv, supports the hypothesis of oscillatory tectonic movements along the coastline of Israel during the late Holocene. The marine to estuarine origin of this terrace is indicated by the presence within it of a biocoenosic, sea-marginal to estuarine, assemblage of well-preserved molluscs consisting of taxa tolerating brackish-water, together with a few fresh-water specimens. The transgressive marine sediments onlap and overlie a 2700-yr-old middle Iron Age (Phoenician) tomb, which was built on a dark clay layer, containing a middle Bronze HB (3750 yr B.P.) settlement. In post-Roman times the coastal zone at this site, both east and west of the present coastline, was first subjected to tectonic subsidence of a few meters, and was then tectonically uplifted to its present altitude.

The dating of the 6 to 8-m shoreline in southern Africa as early Pleistocene prompted a reassessment of evidence from archaeological cave sites on the south coast of the Cape Province which had suggested that this shoreline is of last interglacial age. The successions in the caves at Klasies River Mouth and Die Kelders have been misinterpreted. In fact, they confirm a pre-last interglacial age for this feature. These sites, together with Herolds Bay Cave, indicate that in southern Africa the only last interglacial shoreline above present sea level is at about 4 m, and that it dates from isotope substage 5e.

Glacial lake sedimentary records from Hector Lake in Banff National Park, Alberta, are examined with the aim of clarifying the relationship between glacial activity and outwash sedimentation. Rhythmic couplets in lake bottom sediments provide a method for accurate documentation and dating of recent sedimentation chronology, as analysis of 137Cs content indicates that the couplets are of annual periodicity (i.e., varves). A comparison of sedimentation rate records with recent regional glacial history indicates that high sedimentation rates of one to a few decades duration occur either during and immediately following periods of moraine deposition (ie, maximum ice stands) or during periods of rapid ice recession. Comparison of sedimentary records with somewhat longer term glacial and vegetation records indicates that sedimentation rate variations of several centuries duration closely parallel changes in upvalley ice extent. Over this time scale, high sedimentation rates occur during periods of relatively increased ice extent, low rates during periods of reduced ice extent. Within this general pattern, however, sedimentation rates may remain very high for nearly a century following maximum ice stands, due to the exposure of unstable glaciogenic deposits to fluvial reworking during ice recession.

U-series analyses have been made of travertine samples from the archaeological site at Ehringsdorf-Weimar. The lower Travertine, in which hominid remains were found, yields apparent ages from >350,000 to 200,000 yr. Correlation between isotope ratios yields an age of about 230,000 yr. One sample of the upper Travertine gives and age of 111,000 ± 47,000 yr. Both upper and lower travertines contain fauna and flora indicative of interglacial conditions. The lower Travertine was deposited during isotope stage 7, while the upper Travertine may have been formed during isotope stage 5. This contradicts most earlier biostratigraphic studies which assigned both lower and upper Travertines to stages of the Eem interglaciation (correlative with isotope stage 5). The fauna and flora of the lower Travertine are significantly different from those of the upper Travertine, however, and in some respects are transitional to those of the travertines of Bilzingsleben, which appear to be older yet.

Annual growth records from trees at timberline in the Cascade Range of Washington are correlated with variations in temperature and snow depth and used to reconstruct climatic variation in the past. Response surfaces indicate that growth of mountain hemlock (Tsuga mertensiana) and subalpine larch (Larix lyallii) is positively correlated with summer (July to September) temperature and negatively correlated with spring (March) snow depth when snow depth is at or below average. During years of above average snow depth, temperature has little effect on mountain hemlock but has a negative effect on growth in subalpine larch. These interactions make it difficult to reconstruct these climatic variables separately using standard methods. Mean annual temperature values, which combine information on both summer temperature and spring snow depth, were estimated from a regression model that reconstructs past temperature at Longmire, Washington, as a function of larch and hemlock tree-ring chronologies. The reconstruction of mean annual temperature shows temperatures between 1590 and 1900 to be approximately 1°C lower than those of the 20th century. Only during a short period from 1650 to 1690 did temperatures approach 20th-century values.

Four cores from Lake Mendota in the Yahara River valley of south-central Wisconsin provide pollen, charcoal, and sediment-year. Derived estimates of stratigraphic evidence of a middle Holocene dry period in the northern Midwest. The lake level was lower between about 6500 and 3500 yr B.P. indicating that runoff from the upper Yahara River basin may have ceased during the drier seasons of the precipitation between 6500 and 3500 yr B.P. indicate a decrease of about 10% (down to about 700 mm) from the present precipitation value of 800 mm. A warming between 6500 and 3500 yr B.P. is also interpreted based on a change of vegetation from rich mesophytic forest before 6500 yr B.P. to Quercus savanna, with increased charcoal abundances after that time. After 3500 yr B.P., a closed Quercus forest and decreased charcoal suggest a cooler and wetter climate. The qualitative paleoecological interpretations, quantitative precipitation reconstructions based on pollen from the region (including the Lake Mendota data), and estimates of hydrologic budget based on lake-level changes, all show indications of a dry and warm middle Holocene. Evidence from a large regional array of sites also supports these interpretations.

Radiocarbon dates from archaeological sites in Whitewater Draw, Arizona, place the Sulphur Spring stage of the Cochise Culture between 8000 and 10,000 yr B.P., and possibly back to 10,400 yr B.P. Geoarchaeological investigations of Whitewater Draw do not substantiate an earlier claim that Sulphur Spring stage ground stone artifacts are associated with extinct megafauna, nor the hypothesis that Sulphur Spring stage artifacts are specialized plant processing tools of the Clovis Culture.