The reef tracts of Barbados have been investigated by electron spin resonance dating; all parameters necessary for ESR dating (including effective α-efficiency and thermal stability) were determined without cross checking with another independent dating method. In addition, some U-series analyses were carried out in order to test the reliability of ESR. In most cases, the results show a satisfactory agreement between ESR and both these and previously published U-series dates (M. L. Bender, R. G. Fairbanks, F. W. Taylor, R. K. Matthews, J. G. Goddard, and W. S. Broecker (1979). Geological Society of America. Bulletin 90 , 577–594). For the oldest samples, ESR dates tend to exceed He/U dates, suggesting that there might have been He loss from aragonite. Raised reef tracts are assigned to high sea stands from successive interglacial stages 5, 7, 9, 11, 13, and 15. ESR and U-series (230Th/234U) dates for corals and molluses in North Barbados do not support the suggestion of N. P. James ((1971). Unpublished Thesis, McGill University, Montreal) that this region has subsided during part of the past 125,000 yr. Whereas the experimentally determined mean life (τ) of trapped electrons is only 500,000 yr for the ambient temperature in Barbados, there is no evidence from the comparison between ESR and other dates for thermal fading. This emphasizes the difficulty of experimental measurement of τ.

The global model of postglacial relative sea level variations that has been developed over the past decade is employed to investigate the constraints that it may be invoked to place on the timing of the deglaciation of West Antarctica. The analyses presented here confirm the suggestion of P. Wu and W. R. Peltier (1983, Geophysical Journal of the Royal Astronomical Society 74 , 377–450) that the model of this event employed in J. A. Clark and C. S. Lingle (1979Quaternary Research 11 , 279–298) may be simply modified to rectify the misfits between theory and observation that are otherwise obtained at Southern Hemisphere sites. A large number of Southern Hemisphere relative sea level data are shown to require that the retreat of Antarctic ice substantially lagged the retreat of Northern Hemisphere ice if the deglaciation of Antarctica was abrupt. The time of onset of Antarctic deglaciation is thereby shown to coincide with the time of most rapid Northern Hemisphere deglaciation. Sensitivity tests are performed which demonstrate that this result is relatively insensitive to the discretization employed to represent the ocean basins; the only exception to this general rule obtains at some coastal sites at which a trade-off is revealed between the delay of West Antarctic melting and the thickness of the lithosphere required to reconcile the observed local variations of relative sea level. At such sites, which are all in the far field of the ice sheets, some attention must be paid to the accuracy of the local finite element representation of the oceans and to the details of the Antarctic deglaciation history.

New evidence from the Asov Sea-Black Sea region shows that after the Cobb Mountain magnetic event (1.1 myr) there were 8 saline water events, with Mediterranean molluscs penetrating into the Asov Sea (five times farther than the western Manych Strait), and 7 or 10 cold freshwater events. During the freshening phase, the Caspian Sea molluscan fauna penetrated into the Black Sea; each time the Caspian mollusc assemblage was characterized by a new species of Didacna. Thus, some 18–20 bioclimatostratigraphic units can be distinguished in the Asov Sea-Black Sea section for the last 1 myr. Their numerical age is estimated by some dozen thermoluminescence dates and 12 magnetic-polarity datum planes. The Karangatian s. lato corresponds to the interval 300,000–50,000 yr, the Uzunlarian to 580,000–300,000 yr, and the Chaudian to 1,100,000–600,000 yr. The Karangatian and Tyrrhenian marine terraces correspond to marine isotope stages 5 and 7, the Uzunlarian and Milazzian to stages 11–15, and the Chaudian and Sicilian to stages 16–28. The number and ages of glacial-interglacial cycles in continental Europe are identical to the climatic cycles in the Black Sea and Mediterranean.

A synthesis of previous work and new data on the stratigraphy of high terraces of the Ohio and Monongahela Rivers upstream from Parkersburg, West Virginia, indicates a correspondence between terrace histories in the ancient Teays and Pittsburgh drainage basins. Four terraces are identified in each. Sediments of the lower three alluvial and slackwater terraces, correlated with Illinoian, early Wisconsin, and late Wisconsin glacial deposits, have been traced along the modern Ohio River through the former divide between the Teays and Pittsburgh basins. Sediments in the fourth terrace, the highest well-defined terrace in each basin, were deposited in two ice-dammed lakes, separated by a divide near New Martinsville, West Virginia. Some deposits of the highest slackwater terrace in both the Teays and Pittsburgh basins have reversed remanent magnetic polarity. This, and the stratigraphic succession in the two basins, suggests that both were ponded during the same glaciation. Reversed polarity in these terrace sediments restricts the age of the first ice-damming event for which stratigraphic evidence is well-preserved to a pre-Illinoian, early Pleistocene glaciation prior to 788,000 yr ago. In contrast, slackwater sediments in the Monongahela River valley, upstream from an outwash gravel dam at the Allegheny-Monongahela confluence, have normal remanent magnetic polarity, corroborating correlation with an Illinoian ponding event.

Thick deposits of Roxana Silt are recognized only along the Illinois River (downstream from the Woodfordian terminal moraine) and are generally interpreted as being mainly loess, with the bulk accumulating from about 40,000 to 30,000 yr ago in association with an Altonian-age glacier in northeastern Illinois. Yet 11 14C dates indicate that southern Michigan was not ice-covered during that interval; thus, any proximate ice must have, at best, been restricted to Great Lakes basins, an interpretation supported by the absence of late Altonian till at critically located Michigan, and nearby, sites. Late mid-Wisconsinan ice did, however, obstruct eastern drainage of the ancestral Great Lakes. Such glacial blockage, the distribution of many Michigan organic deposits within pre-Woodfordian lacustrine sediments, and radiocarbon dates suggest that, more than once, late Altonian lakes associated with the Lake Michigan basin drained into the Illinois River. Erosion of lake and spillway bluffs along with repeated river fluctuations provided a source for the thick, geographically restricted Roxana Silt. Meanwhile, along other nearby rivers the supply was meager and the loess thin.

Radiocarbon age control on the type Glenwood, Calumet, and Toleston shoreline features and on the abandoned Chicago outlet at the south end of the Lake Michigan basin provides a basis for reevaluating the timing and causes of high lake phases in the basin. Radiocarbon dates suggest that Glenwood-level (195 m) shoreline features formed between 14,100 and 12,700 yr B.P. (Glenwood I and II phases), Calumet-level (189 m) between 12,700 and 11,000 yr B.P. (Calumet I and II phases), and Toleston-level (184.5 m) between 5000 and 4000 yr B.P. (Nipissing phase), and that the Chicago outlet was cut to its present level (180 m) on bedrock while the lake was at the Glenwood level. This new chronology is inconsistent with J H. Bretz' hypothesis ((1951) American Journal of Science 249 , 401–429) that the progressive lowering of lake level resulted from episodic down-cutting of the outlet. Instead, the changes in lake level appear to relate to changes in the amount of glacial meltwater and precipitation entering the basin. We hypothesize that the Glenwood phases correspond with times when discharge from the Huron and Erie basins also entered the Lake Michigan basin (Lake Border and early Port Huron glacial phases), the Calumet phases with times when drainage was from the Lake Michigan basin alone (late Port Huron and Two Rivers glacial phases), and the Nipissing phase with the postglacial middle Holocene transgression caused by differential uplift in the basin. Estimates of relative net inputs to the basin during the Glenwood, Calumet, and Nipissing lake phases are consistent with estimates of relative outputs (i.e., discharge through the Chicago outlet); the magnitude of relative differences in inputs and outputs between phases is sufficient to explain lake-level changes of 4.5 to 6 m.

Between 7000 and 6000 yr B.P., relative sea level was as much as 5 m lower than today in the St. Lawrence estuary, Québec. A small transgression (Laurentian transgression) occurred between 5800 and 4400 yr B.P., which resulted in the construction of an 8- to 10-m terrace. About 3000 yr B.P., relative sea level was similar to present, and then a stillstand or a slight rise occurred during which a cliff (Micmac cliff) was cut into the emerged terrace. During a subsequent lowering of relative sea level (coastal emergence), a low aggradational terrace (Mitis terrace) was built between 2300 and 1500 yr B.P. at the base of the Micmac cliff. A new emergence curve for the south shore of the St. Lawrence estuary showing a mid-Holocene high stand of relative sea level is therefore proposed.

Ostracod and pelecypod carbonate preserved since the latest Pleistocene in the bottom sediments of Lake Zürich was probably formed under constant temperature conditions. Temporal shifts in the oxygen-isotype ratios for those carbonates therefore correspond to shifts in the isotopic character of the net lake inflow. Alpine deglaciation, which released isotopically light meltwaters, commenced prior to ca. 15,000 yr B.P. and was essentially completed in northern Switzerland by 12,4000 ± 250 yr B.P., well before substantially increased atmospheric heat was available from either increased insolation or an increased atmospheric CO2 content. The early Holocene climate for the region was characterized by minor short-term fluctuations in mean annual air temperatures and an overall amelioration of up to 2°C. Contemporaneously precipitated authigenic and biogenic carbonates have recorded partitioning of carbon isotopes between surface and bottom waters during photosynthetic production and subsequent oxidation of organic matter in the lake. The degree of that partitioning provides an index of the relative production rates, which were low in the late Pleistocene meltwater lake but considerably enhanced during the Holocene.

A series of submerged archaeological sites found on the continental shelf between Haifa and Atlit indicate a continuous marine transgression between 8000 and 1500 yr B.P. The sites are embedded in the upper part of a marshy clay that fills the trough between the coastal aeolianite (kurkar) ridge and a ridge now submerged some 1000 to 1500 m to the west. The submerged prehistoric sites belong to two main chronological units: Prepottery Neolithic B (8000 yr B.P.) and late Neolithic (ca. 6500 yr B.P.); these were found at depths of 12 to 8 m and 5 to 0 m, respectively. Bronze Age and Byzantine anchors were found at depths of 5 to 3 m and 4 to 1.8 m, respectively. As the archaeological materials are firmly dated, we can reconstruct the rate of marine transgression from 8000 yr B.P. to the present and the eastward movement of settlements through time as related to the transgression.

The general lack of an age-diagnostic biostratigraphy in the Neogene sediments of the abyssal Arctic Ocean has emphasized the importance of magnetostratigraphy in providing chronostratigraphic control in these sediments. Sedimentation rates interpreted from early magnetostratigraphic studies of cores taken from the T3 ice island in the western Mendeleev Plain were estimated to be on the order of 1 mm/103 yr; however, recent amino acid epimerization studies of a core from the same area have suggested sedimentation rates of almost 15 mm/103 yr. This controversy has led us to reexamine the paleomagnetism of several of these cores. Our alternating field demagnetization studies indicate that many of these cores have an intense, high coercivity overprint, acquired after the core was opened, that is adequately removed only after treatment at 20 to 70 mT. We have remeasured samples from two cores after demagnetizations up to 80 mT and can confirm the position of the Brunhes/Matuyama boundary originally identified in the cores. In addition, the Jaramillo and Olduvai subchrons are identified. Average sedimentation rates in these two cores are 2–3 mm/103 yr, similar to the original estimates based on reversal stratigraphy, as well as those determined from recent radiocarbon studies, but incompatible with the amino acid-based dates.

The relationship between the stable C-isotope composition of the soil environment and modern climate and vegetation was determined empirically along a present-day climatic transect in the eastern Mojave Desert. The δ13C of the soil CO2 and carbonates decreased with increasing elevation and plant density, even though plant assemblages at all elevations were isotopically similar. Several factors, including differences in the ratios of pedogenic of limestone calcite and differences in past vegetation, were considered as explanations of this trend, However, it appears that in the sparsely vegetated Mojave Desert, the δ13C of pedogenic carbonate is controlled by differences in plant density and biological activity. This relationship may provide a tool for assessing past vegetational densities, as long as the vegetation is isotopically homogeneous.

Deep-sea sediment cores recovered from the Northeast Atlantic Ocean were examined in order to elucidate the influence of the Earth's orbital parameters on major ice rafting. Analyses of coarse-grained ice-rafted debris and planktonic foraminifers revealed a strong reaction to the precession signal. Since 130,000 yr B.P., dropstone layers have been deposited each half period of a precessional cycle (11,000 ± 1000 yr). Ice rafting occurs during times of winter minimum/summer maximum insolation and summer minimum/winter maximum insolation. In the first case, high summer insolation forces meltwater discharge from the ice sheets into the polar seas which subsequently enhances formation of sea ice during the winter. In the second case, growth of continental ice enhances iceberg production which also leads to a salinity reduction of surface seawater. Both situations result in a southward penetration of polar water. Thus, the marine record of dropstones documents ice rafting not only during Weichselian stades but also during cold events within interstades. The regularity of ice rafting yields a useful framework to calibrate and elucidate climatic changes, not only in the region of the North Atlantic Ocean but also in remote areas such as the Pacific Ocean and the Antarctic.

Sediment and microfossil analyses of a 7.5-m core from Lake Cheshi suggest that south-central Africa experienced late Quaternary climate changes similar to those in East Africa. The lake formed around 34,000 yr B.P., after a prelacustrine phase of at least 6000 yr, from climatic or tectonic causes. Ratios of precipitation to evaporation were probably similar to those of today until a decline about 15,000–13,000 yr B.P. when the lake shrank and became chemically concentrated. Maximal lake levels occurred between 8000 and 4000 yr B.P., and were followed by a low stand under presumably arid conditions about 3500 yr B.P. Encroachment of sudd vegetation contributed to shallowing during the last 3000 yr. A phase of microfossil dilution may reflect human activity in the basin, or climatic or hydrological changes. Melosira valve morphology seems to reflect mixing regimes. Sponge and testate amoeba remains were most numerous relative to diatoms during low-water phases.

Well-dated pollen profiles from six sites from Maine to Minnesota record vegetation changes indicative of summer temperature and annual precipitation variations over the past 2000 yr. Laminations in the sediment provide accurate time control. Multiple regression techniques were used to calculate calibration functions from a spatial network of modern pollen and climate data. When applied to the six pollen diagrams, these calibration functions yielded estimates that show a long-term trend toward lower summer temperature. Superimposed on this long-term trend are short-term fluctuations that are frequently in phase at the sites. Departures from the long-term cooling trend are positive around 1500 yr ago (indicating relative warmth) and negative between 200 and 500 yr ago (indicating relative cold). Annual precipitation showed a slight increase at several sites during the past 1000 yr relative to the previous 1000 yr.

Surficial sediments of Gulf St. Vincent, South Australia, are predominantly bioclastic, cool-temperate carbonates. Benthic foraminifera are abundant and distribution of species is closely related to water depth. For example, Massilina milletti is most common at depths ca. 40 m, while Discorbis dimidiatus is characteristics of shallow, subtidal environments. Elphidium crispum, a shallow-water species, and E. macelliforme, favoring deeper water, provide a useful numerical ratio. Their logarithmic relative abundance, in the sediment size fraction 0.50–0.25 mm, correlates strongly with water depth. Vibrocores SV 4 and SV 5 recovered undisturbed sections of Quaternary strata from the deepest part (ca. 40 m) of Gulf St. Vincent. Amino acid racemization and radiocarbon age determinations show that late Pleistocene sections of the cores were deposited over the time ca. 45,000 to 30,000 yr B.P. Species of fossil foraminifera, recovered from these sections, are mostly extant in modern Gulf St. Vincent, thus allowing paleoecological inferences of late Pleistocene sea levels. These inferred sea-level maxima can be correlated with those determined from study of Huon Peninsula coral reef terraces. Initial estimates of tectonically corrected sea levels for transgressions in Gulf St. Vincent at 40,000 and 31,000 yr B.P. are −22.5 m and −22 m, respectively. The intervening regression lowered sea level to −28 m.

Eleven radiocarbon age determinations clearly show that a lens of Holocene fluvial organic debris on the Alaskan Arctic Coastal Plain contains mostly pre-Holocene organic material. Radio-carbon ages of identified plant macrofossils indicate the material was deposited about 9000 to 9500 yr B.P. Radiocarbon analyses of bulk samples from this deposit, however, range from 13,300 to 30,300 yr B.P. Most of the old organic matter seems to be in the smaller size fractions in the deposit, particularly in the fraction between 0.25 and 0.5 mm, but all size fractions are contaminated. Particular caution must be exercised in submitting bulk samples for radiocarbon dating from areas where conditions favor redeposition of isotopically “dead” carbon.

Strata at Landguard Bluff, near Wanganui, New Zealand preserve a clear record of relative sea-level changes during oxygen-isotope stage 7. Two relative high sea-level stands (during stages 7a about 210,000 yr ago and 7c about 240,000 yr ago) are separated by a relative low sea level (stage 7b) that was at least 32 m lower than present. Pollen analysis of sediment deposited during stage 7b indicates climate at the time was up to 3°C cooler than present. The climate and sea-level evidence from Landguard Bluff are consistent with oxygen-isotopic evidence from deep-sea cores indicating a marked cooling during stage 7, which is closely associated with a summer radiation minimum centered at about 230,000 yr ago in the Northern Hemisphere.

Pollen diagrams from Joe and Niliq Lakes date to ca. 28,000 and 14,000 yr B.P., respectively. Mesic shurb tundra grew near Joe Lake ca. 28,000 to 26,000 yr B.P. with local Populus populations prior to ca. 27,000 yr B.P. Shrub communities decreased as climate changed with the onset of Itkillik II glaciation (25,000 to 11,500 yr B.P.), and graminoid-dominated tundra characterized vegetation ca. 18,500 to 13,500 yr B.P. Herb tundra was replaced by shrub Betula tundra near both sites ca. 13,500 yr B.P. with local expansion of Populus ca. 11,000 to 10,000 yr B.P. and Alnus ca. 9000 yr B.P. Mixed Picea glauca/P. mariana woodland was established near Joe Lake ca. 6000 yr B.P. These pollen records when combined with others from northern Alaska and northwestern Canada indicate (1) mesic tundra was more common in northwestern Alaska than in northeastern Alaska or northwestern Canada during the Duvanny Yar glacial interval (25,000 to 14,000 yr B.P.); (2) with deglaciation, shrub Betula expanded rapidly in northwestern Alaska but slowly in areas farther east; (3) an early postglacial thermal maximum occurred in northwestern Alaska but had only limited effect on vegetation; and (4) pollen patterns in northern Alaska and northwestern Canada suggest regional differences in late Quaternary climates.

A total of 50 arthropod taxa were identified from 41 fossil packrat (Neotoma sp.) middens from 160 to 625 m elevation in three study areas in the Lower Colorado River Valley subdivision of the Sonoran Desert. Radiocarbon dates associated with the middens range from >43,200 to 610 yr B.P. The fauna in the Tinajas Altas Mountains, southwestern Arizona, was relatively modern by ca. 10,000 yr B.P. in the early Holocene although a California juniper woodland persisted in the area until 8970 yr B.P. In contrast the fauna of the Hornaday Mountains, northwestern Sonora, increased dramatically in species richness after 4000 yr B.P. Although we are limited by poor taxonomic resolution and by insufficient knowledge of current distributions, the arthropod fauna may have been much more conservative than the regional flora during the last glacial/interglacial climatic cycle. Decreasing differences between modern and glacial climates (both temperature and precipitation) at lower latitudes and elevations may have resulted in minimal changes in the arthropod fauna of the Sonoran Desert lowlands.

One of the lines of evidence cited for possible late Pleistocene human control of horses has been the presence of notching and anterior beveling on horse incisor teeth recovered from upper and middle Paleolithic sites in Europe. Similar forms of wear have been found on the incisor teeth of wild horses from early and middle Pleistocene deposits in North America. Notching appears partly due to malocclusion and chipping. The causes of beveling are less certain but may involve the eating of bark. Therefore, the presence of notching and anterior beveling on horse incisor teeth may not be a reliable indicator of human control.