Lake-level data can be used to refine palaeoclimate reconstructions based on pollen data. This approach is illustrated for the European Holocene. Estimates of P-PET (precipitation minus potential evapotranspiration) were first inferred from modern pollen analogues. The pollen-based estimates were then compared with the status of lakes within a 5° radius. Analogues with P-PET anomalies inconsistent with the lake-level changes were rejected. The "constrained" sets of analogues were used to estimate continental-scale patterns of annual mean temperature and annual precipitation at 3000-yr intervals. Estimated temperature anomalies differed only slightly from the unconstrained reconstructions. Estimated precipitation anomalies, however, showed improved spatial coherence and increased regional contrast and were occasionally reversed in sign. The effect of the constraint was to impose a rational selection among almost equally similar modern pollen analogues with similar temperatures but widely varying moisture regimes. The resulting maps showed clear, spatially coherent patterns of change in precipitation as well as temperature, suitable for comparison with climate-model results. Further improvement of these maps will become possible as a more extensive coverage of lake-level data is obtained.

In the Río Mendoza valley, five Pleistocene drifts and one Holocene drift are distinguished by multiple relative-age criteria, including surface-rock weathering, development of rock varnish, moraine morphology, soil-profile development, and stratigraphic relationships. Several absolute ages suggest a preliminary chronology. During the oldest (Uspallata) glaciation, a system of valley glaciers flowed 110 km from the Andean drainage divide and 80 km from Cerro Aconcagua to terminate at 1850 m. Drift of this ice advance is older than a widespread tephra dated by fission-track at 360,000 ± 36,000 yr. During the Punta de Vacas advance, ice terminated at 2350 m, while during the subsequent Penitentes advance, the glacier system ended at 2500 m. A travertine layer overlying Penitentes Drift has U-series age of 24,200 ± 2000 yr B.P. The distribution of Horcones Drift, which is inferred to represent the last glacial maximum, delimits an independent ice stream that flowed 22 km down Horcones valley to 2750 m. A later readvance (Almacenes) reached 3250 m. Confluencia Drift is considered to be Neoglacial in age and extends downvalley to 3300 m. The moraine sequence is compared with those studied by Caviedes (1972) along Río Aconcagua on the Chilean flank of the Andes.

Multiple tills separated by interbedded lake sediments were temporarily exposed during open-pit mining at Sanford Hill, near Newcomb, in the central Adirondack Mountains of northeastern New York. Radiocarbon ages of wood fragments from brown clay between two tills at that site indicate an age older than 55,000 yr B.P. A pollen profile in the brown pond clay (Tahawus clay) records a transition from initial domination by pine, spruce, and birch to an oak pollen zone. The upward disappearance of spruce and decrease of pine and birch are accompanied by diversification and increase in hardwood pollen. This assemblage includes several warm-climate hardwood species that are not represented in the postglacial flora of the region, suggesting that the biota existed during an interglacial or interstadial interval that was warmer and/or longer than postglacial time. Accordingly, the Tahawus clay is tentatively assigned to the Sangamon interglaciation, and probably to marine oxygen isotope substage 5e. Truncation of the Tahawus clay by glacial erosion may account for the absence of a Sangamon paleosol.

The simultaneous operation of regressive and progressive pedogenetic pathways raises the possibility that soil evolution may exhibit patterns far richer and more complex than increasing development over time. This possibility is explored via a numerical model incorporating the relative rates of progressive and regressive pedogenesis and feedbacks between these rates and the degree of soil development. This model may exhibit deterministic chaos and sensitive dependence on initial conditions with realistic parameter values. Variations in profile development in a region of the North Carolina Coastal Plain where soil-forming factors are relatively constant is consistent with deterministic chaos. Chaotic soil evolution suggests that soil development may reflect the interplay between progressive and regressive soil-forming processes in addition to—or instead of—the age of a surface or deposit. The former may produce a state of development which is unique to a particular time, sensitively dependent on the (unknown) initial conditions, and not simply related to age. Soils and their genetic signatures as indicators of relative ages and Quaternary environments may need to be reinterpreted in this light.

As many as six levels of emerged Holocene coral terraces occur along 40 km of coastline on the Huon Peninsula, Papua New Guinea, recording uplift history since culmination of the postglacial transgression. The Holocene reef crest, ca. 6000 yr B.P., is tilted down to the northwest, parallel to the coast and concordant with the deformation of the last interglacial coral reef terrace, and descends from 23 to 12 m in the study area. The pattern and rate of deformation have been uniform in the late Quaternary because average uplift rates have remained the same since the last interglaciation. The Holocene terraces described here are erosional features with regressive encrusting corals, developed upon the Holocene transgressive reef. The multiple levels represent episodic, probably coseismic uplift, which has occurred repeatedly in the last ca. 6000 yr. Significant longshore variation in the age of the lowest terrace, from 1700 to 2500 yr B.P., suggests independent coseismic uplift on different sectors of the coast. This is supported by age-height relationships of the higher Holocene terraces. Nonlinear uplift during the Holocene, with recurrence intervals increasing toward the present, is clearly recorded by the regressive terraces in each subregion. Some of the Holocene regressive terraces grade laterally into fluvial terraces capped with debris-flow deposits, probably reflecting seismically triggered mass movement.

Holocene emergent reefs and notches are well distributed on Rota and Guam. Relative sea-level changes at these islands are reconstructed based on geomorphological observations and borings on present and emergent reefs, together with 54 radiocarbon dates. Sea level rose gradually to a maximum of 1.8 m between 6000 and 4200 yr B.P. and reached its highest level by 4200 yr B.P. on both islands. After 3200 yr B.P. abrupt uplift caused emergence of the reef. By subtracting the tectonic effect, we obtained the sea-level change in the Marianas: sea level reached its present level by 4200 yr B.P. and has remained almost stable since then. Reconstructed late Holocene sea-level change in the Mariana Islands provides constraints on geophysical models of sea-level variations.

The rivers of central Australia rise in the MacDonnell Ranges and flow out across broad, low-relief plains into the surrounding desert. The stratigraphy of the Ross River plain records the areal extent and frequency of Holocene floods. This floodout plain is underlain by deeply weathered alluvial deposits, characterized by red earth soils dated by thermoluminesence at >59,000 yr. This old alluvium is covered by a sheet-like deposit of very silty sand of probable eolian origin dated by thermoluminesence at 9200 ± 900 yr. The oldest Holocene alluvium occurs as broad, low-relief bars and levee deposits flanking the modem channel and as low-relief long-wavelength bedforms that fan out across the plain. This deposit resulted from a flood flow, up to 10 km wide, that covered the entire plain. Evidence for several large floods between 1500 and 700 yr B.P. is also preserved in a 500- to 1500-m-wide paleochannel. Thus, the surface features on the floodout plains are the product of a few rare large flood events. This paleohydrologic record is additional evidence of the dynamic nature of the hydrometerological regime of central Australia.

Quantitative estimates of late-Quaternary climate in the northeastern United States are reconstructed from fossil pollen data to evaluate changes in the regional moisture balance inferred from water-level fluctuations. We use environmental response surfaces to calibrate modern pollen data (for 17 different taxa) to an index of effective soil moisture and mean annual precipitation. We apply these response surfaces to fossil pollen data from 60 sites in the region to reconstruct changes in soil moisture and mean annual precipitation at 3000-yr intervals from 12,000 yr B.P. to present. The mapped reconstructions of soil moisture and mean annual precipitation illustrate how the regional moisture balance of the Northeast may have changed over the last 12,000 yr in response to changing climate. Reconstructions of annual precipitation show a gradual increase from 30% below modern values at 12,000 yr B.P. to near-modern values by 6000 yr B.P. and then remain relatively constant thereafter. Reconstructed changes in the index of effective soil moisture, however, show a pattern of near-modern values at 12,000, 6000, and 3000 yr B.P., with significantly lower values estimated for 9000 yr B.P., the time of maximum pine pollen abundances in the Northeast. This pattern of change is similar to the change in regional moisture balance inferred from stratigraphic records of water-level fluctuations. These results confirm previous interpretations, based on records of water-level fluctuations, that conditions in the Northeast were significantly drier during the early to middle Holocene than at other times during the last 12,000 yr.

New detailed pollen analysis of the lower part of the Upper Pliocene Semaforo section (Crotone, Italy) documents cyclic behavior of vegetation at the beginning of the Northern Hemisphere glaciations. The competition between four vegetation units (subtropical humid forest, deciduous temperate forest, altitudinal coniferous forest, and open xeric assemblage) probably reflects modifications of vegetation belts at this montane site. Several increases in herbaceous open vegetation regularly alternate with subtropical humid forest, which expresses rapid climatic oscillations. The complete temporal succession—deciduous forest (rich in Quercus), followed by subtropical humid forest (Taxodiaceae and Cathaya), then altitudinal coniferous forest (Tsuga, Cedrus, Abies, and Picea), and finally herbaceous open vegetation (Graminae, Compositae, and Artemisia )—displays the climatic evolution from warm and humid interglaciation to cold and dry glaciation. It also suggests an independent variation of temperature and humidity, the two main climatic parameters. The vegetation history of southern Calabria recorded in the Semaforo section have been correlated with the ∂18O signal established in the Atlantic Ocean.

The malacofaunas of Burgundy, France, reflect changes in climate and the activities of man during the Holocene. Statistical analyses based on the Shannon diversity index and correspondence analysis are used to describe the mollusk assemblages in a composite sequence based on three well-dated sites. The variation demonstrated by the mollusks suggests that a two-step warming took place between 10,000 and 9000 and 8000 and 6000 yr B.P. in relative agreement with the timing of the deglaciation in the tropical Atlantic Ocean proposed by Mix and Ruddiman (1985, Quaternary Science Reviews 4, 59-108). High humidity, partly associated with widespread inundations of the valleys between 10,000 and 8000 yr B.P., may be related to estimated variations in the rate of freshwater discharge to the Atlantic Ocean reported by Fairbanks (1989, Nature 342, 637-642). The increasing impact of human activities on the environment during the past 2000 yr is indicated by the low diversity of the mollusk assemblages, demonstrating the need for careful interpretation of the youngest Holocene sediments in this region.

A fossil assemblage containing molluscs, ostracodes, and fish has been recovered from lacustrine sediments from near Connersville, southeastern Indiana. The reversed remanent magnetic signature of the sediments and the extent of isoleucine epimerization in molluscan shell protein indicate a pre-Illinoian age for the fossils. The fauna includes four taxa of fish, Coregonus sp., cf. Prosopium sp., cf. Thymallus arcticus, and Catostomus sp.; four taxa of ostracodes, Cytherissa lacustris, Candona caudata, Cyclocypris ampla, and Candona sp.; and 28 taxa of molluscs. Elements of the aquatic molluscs, fish, and ostracodes suggest a cool-water lake (8° to 16°C). The terrestrial molluscs include boreal species that now reach the southern limits of their range in the Great Lakes region near the north shore of Lake Superior and imply average summer temperatures of about 15°C near the lake margins. The lake may have been formed when West Lebanon ice advanced into the Anderson-New Castle Buried Valley system which drained northwest as a tributary of the Lafayette Bedrock Valley System.