Reinterpretation of seismic-reflection data from Cape Cod Bay has produced a revised late Wisconsinan history. Acoustically laminated deposits, originally inferred to be glaciolacustrine, are shown to be glaciomarine by tracing them to glaciomarine mud in Stellwagen Basin, north of Cape Cod Bay. A late Wisconsinan marine deposit of nonglacial origin overlies the glaciomarine deposits in Cape Cod Bay. Both deposits indicate that the crust was isostatically depressed below the late Wisconsinan eustatic sea level and that deglaciation and marine submergence occurred simultaneously. Valleys cut into the marine deposits, both glacial and nonglacial, indicate that a low sea-level stand, the result of isostatic rebound, occurred shortly after the marine incursion. A transgressive uncomformity and marine deposits, both mostly of Holocene age, overlie the late Wisconsinan deposits. The marine incursion, regression, and Holocene transgression represent the northward passage of an isostatically induced peripheral bulge following deglaciation. In turn, the bulge, a response to crustal loading and unloading, indicates thick glacier ice in the terminal zone and lends support to arguments for a maximum Laurentide ice model. Evidence for a late Wisconsinan marine incursion, regression, and the passage of a peripheral bulge should be sought in the other bays and sounds of the New England terminal zone.

Sharp jumps in climate punctuate the records from borings in the Greenland ice cap during the time interval 60,000 to about 20,000 yr ago. Rapid fluctuations are also seen in foraminifera records for cores from the northern Atlantic and in a pollen record from a core from a bog in the Vosges Mountains in France. In this paper we present a new radiocarbon chronology for northern Atlantic deep-sea core V23-81 which permits comparison with the radiocarbon-dated Vosges Mountains pollen record. Because of the lack of a 14C chronology for the Greenland ice record and of distortions peculiar to each of the three records, it is not yet possible to say whether or not the events are genetically related.

About 2000 large sediment samples were collected during the early 1960s throughout the continental shelf off the Atlantic coast of the United States to establish and map sediment types including sediments relict from times of glacially low (and subsequently higher) sea levels. In about 510 of these samples we found fossil shells of mollusks remaining from environmental conditions different from those at present. Publications and collections by others contain about 70 additional samples having relict mollusks. Some of these shells indicate lower sea levels, others colder water, and still others warmer water than is now present. Radiocarbon measurements from earlier studies by us and others established the dates of colder water (late Pleistocene), and we made additional measurements to learn the dates of warmer water (about 1000 to 2000 yr B.P.). The results show reasonably enough that continental shelves are the sites of relict faunas as well as of sediments that indicate changed and complex environmental histories.

Southeasternmost Baffin Island is mantled by Hudson Strait drift; it contains abundant limestone erratics and 20 to 50% carbonate in the matrix. To the northwest, it is replaced by drift dominated by locally derived rock of the Canadian Shield. The sense and orientation of ice-erosional features demonstrate that Hudson Strait drift is associated with northeasterly ice flow that crossed the tip of Meta Incognita Peninsula; local drift, associated with ice flow S10°W along the Hudson Strait coast, was derived from a dispersal center on the peninsula. Erratic lithologies contained in the Hudson Strait drift indicate a Labradorean provenance. Large-scale bedrock molding and the distribution of cirques indicate NE-flowing ice has been dominant throughout the middle and late Quaternary. Radiocarbon dates of in situ shells confirm that deglaciation began more than 11,000 yr ago, with the Frobisher Bay coast becoming ice free by 9300 yr ago. Five dates from Hudson Strait suggest that the strait was deglaciated before 9000 yr BP. However, ice from the Labradorean Sector recrossed Hudson Strait during the Cockburn Substage, about 8500 yr ago, damming drainage from the west. Final retreat of Labradorean ice from Baffin Island was complete by 8000 yr ago, at which time the sea was able to penetrate Hudson Bay.

Analysis of colluvial, fluvial, and bog sediments at Flat Laurel Gap (1500 m) in the Blue Ridge Mountains of North Carolina provides a record of late Quaternary landscape evolution. Thermoluminescence (TL) analysis provides the first absolute-age determinations available for presumed periglacial deposits in the southern Appalachian Mountains. The Pleistocene/Holocene transition, dated between 11,900 and 10,100 yr B.P., represents a period of climatic amelioration and a change from colluvial to alluvial processes. A TL date of 7400 ± 1000 yr B.P. for matrix within a block-stream indicates possible early Holocene reworking of Pleistocene periglacial colluvium. Organic sediment deposition in a bog that began about 3400 yr B.P. increased in rate from 0.02 to 0.09 cm/yr with the onset of logging and land clearance about 1880 A.D.

Time series of grain-size distributions from Pleistocene sediments deposited in Lake Biwa during the past 550 millennia show dominant periods of 40,000 and 20,000 yr that are very close to those predicted by the Milankovitch theory, as well as a period of about 70,000 yr not directly predicted by this theory. The 70,000-yr period is strongest, followed by the 20,000-yr period. The sequences also show that coarser particles were deposited, in general, during strong solar insolation, whereas finer particles were deposited during weak insolation.

The microprobe-determined glass shard major element chemistry of tephras derived from five North Island, New Zealand volcanoes (Mayor Island, Okataina, Taupo, Tongariro, and Mount Egmont) and younger than ca. 20,000 yr B.P. was subjected to discriminant function analysis. Four separate approaches were adopted to test the match of the tephras with their known sources: (1) an analysis of raw microprobe data; (2) an analysis of normalized data; (3) an analysis of the data transformed by calculating the log10 of oxide scores divided (arbitrarily) by the chlorine content; and (4) a repeat of (3) with multivariate outlier scores, as determined by principal components analysis, deleted. All yielded excellent classification functions (efficiencies of 91–100%), with the eruptives associated with each of the five volcanoes being chemically distinct from one another. In each approach, the first two canonical discriminant functions accounted for >90% of the variation between groups. The removal of multivariate outliers from the data set had only minor effects on the performance of the discriminant function procedures. Separate discriminant function analysis of the relatively alike Taupo and Okataina eruptives gave a greater degree of multivariate separation. The numerical classifications generated should enable unidentified tephras erupted since ca. 20,000 yr B.P. from the five volcanoes to be provisionally matched with their sources.

High latitude intracontinental seaways occupy great troughs carved by broad tongues of inland ice as it debouched to deep marine water. Such troughs occur in glaciated coasts, but not in stable, nonglaciated ones. Where ice flowed along the walls of troughs whose adjacent uplands held local glaciers, the walls simulate alpine troughs with faceted spurs and submarine hanging tributary valleys. Where uplands were not glaciated, trough walls are unbreached. Where ice flowed across them, coasts are digitate in low relief. In the northeastern sector of the Laurentide Ice Sheet, large glacial grooves converge toward the Gulf of Boothia-Prince Regent Inlet-Lancaster Sound avenue of egress to open sea, suggesting that it was an exit for inland ice which shaped it to its present form. The subduction Pacific coast of the Americas is mostly harborless in nonglaciated latitudes, but in southern Chile and British Columbia it is dissected. A circular gravity high 2800 km across is concentric with the area covered by the Laurentide Ice Sheet. Abyssal glacial silts are voluminous enough to account for an average of 100–150 m of erosion over the area covered by the Laurentide Ice Sheet.

A continuous pollen record from a central African highland site (3°28′S, 29°34′E) with 15 radio-carbon dates spans at least the last 40,000 yr. Both modern and fossil pollen have been investigated. A clear pattern of changes in vegetation and climate is suggested. Prior to 30,000 yr B.P., the occurrence of the montane conifer forest, including the upper forest limit, indicates climatic conditions colder and drier than now, but more humid than in late-glacial time. Between 30,000 and 15,000 yr B.P., grassland with afroalpine indicators expanded down to 2500-2000 m altitude as a result of dry, and most probably cool, climate; the montane forest persisted in refuges, although much reduced. Forest vegetation with the same floristic composition as today appeared after 13,250 ± 200 yr B.P., suggesting more humid conditions. The occurrence of a possible short-term humid episode about 21,500 yr B.P. is correlated with some high lake-level stages in East Africa and with organic deposits in deep-sea cores from the Mediterranean and the Atlantic Ocean.

We measured the offsets of six stream valleys, of 30 to 90 m, along the northwest-southeast trending, left-lateral Haiyuan strike-slip fault, in north-central China. Minimum ages of these offsets were determined to estimate lower bounds for the Holocene slip rate. The most reliable bounds are 7.6 ± 1.0 and 6.7 ± 1.0 mm/yr, with three others that are smaller (3.4 ± 0.7, 3.5 ± 0.9, and 4.1 ± 0.4 mm/yr) and one large value (16.4 ± 5.9 mm/yr) that we doubt. Thus, the average Holocene slip rate of the Haiyuan fault is larger than 6 mm/yr and probably exceeds 7 mm/yr. If the average slip rate of 5 to 10 mm/yr for the Quaternary Period is applicable to the Holocene Epoch, the average rate is 8 ± 2 mm/yr.

Data from 291 small lakes and mires in eastern North America provide information on the natural variability of rates of sediment accumulation in these environments over the last 18,000 yr. Accumulation rates were calculated by linear interpolation between radiocarbon and biostratigraphic dates from sediment cores taken for pollen analysis. Within the data set, the rates were lognormally distributed with a mean accumulation rate of 91 cm/103 yr, and a range from less than 1 to over 3500 cm/103 yr. The accumulation rate data were divided into five subsets that were temporally or spatially distinct and therefore represent different geomorphic and climatic conditions at the time of deposition. Sediments deposited in basins north of 50°N, south of 40°N, and before 10,000 yr B.P. accumulated at much slower rates than sediments accumulating in midlatitude basins (between 40° and 50°N) between 10,000 and 330 yr B.P. Sediment accumulation over the last 330 yr has, on average, been at rates four to five times faster than any time previously. Inorganic sediments that could be radiocarbon-dated have accumulated at significantly lower rates than organic sediments, reflecting differences in depositional processes. For midlatitude basins during the Holocene, the most likely rate of continuous sediment accumulation within our data set is 65 cm/103 yr. Rates below 10 cm/103 yr are likely to be associated with nonconstant processes of sediment accumulation.

From 41,000 to over 22,000 yr B.P., a massive and areally extensive spring travertine was deposited in the Bet Shean Valley, Israel. This travertine is coeval with the Ami'az Member of the Lisan Formation which represents a high lake stand. The travertine deposition is contemporaneous with a more active hydrologic regime associated with wetter conditions in the arid zones of the southern Levant adjacent to southern Israel. These wetter conditions facilitated formation of a widespread spring tufa and also enhanced the water levels of Lake Lisan.

Temperature variations over Europe are reconstructed for a 6-month “summer” season from April to September for the period 1750–1850 using a network of maximum latewood density chronologies of coniferous trees. Around 44% of the variance of the whole temperature grid was explained in calibration. Independent verification indicates that over the reconstruction period the explained variance averaged over the whole grid should lie in the range 30 to 35%. The reconstructions are better in the north of the region (about 50% explained temperature variance based on comparison with independent climate data) than in the south (below 20%). The temperature recontructions indicate cooler summers over Europe from 1812 to 1816 and during the 1830s. The summers of the 1820s were the warmest reconstructed. Decadal variations occur on a regional scale but no similar periods of anomalously cooler or warmer summers occurred between 1750 and 1810 throughout Europe.

An extended chronology of Lahontan basin lake levels based on uranium-series age estimates correlates with the global ice-volume record. Lake highstands occur at or shortly after times of maximum ice-sheet size. Moderate size lakes occur when the global ice volume is about 80% of its maximum. The data indicate that lake levels rise and fall relative to the proximity of the mean position of the jetstream. When the continental ice sheet is above some threshold size or shape, it appears that the large-scale circulation and climatic conditions are right for producing lakes of moderate to large size within the Lahontan basin.

The late Quaternary vegetation of northern Isla de Chiloé is inferred from palynological analysis of a section in the Río Negro drainage (42°03′S, 73°50′W). At ca. 30,500 yr B.P., maxima of Astelia and Donatia occurred, suggesting wetland development. From that time until ca. 27,000 yr B.P., steppe indicators such as Compositae/Gramineae dominated, suggesting drier conditions. After 27,000 yr B.P., the moorland shrub Dacrydium gradually increased, reaching a maximum by 18,000 yr B.P. At this time Astelia increased again, suggesting development of cushion bog during cold and wet conditions. The glacial-postglacial transition is characterized by a marked change from peaty sediments to clays, a decrease in the cushion bog flora, and the prevalence of Gramineae/ Compositae and swamp taxa. This vegetation prevailed until ca.7000 yr B.P. when forest taxa became dominant. The floristic pattern inferred from the pollen spectra of the Rio Negro section suggests that the late Pleistocene vegetation of Chiloé resembled modern Magellanic Moorland vegetation (52°–56°lat S). Based on climatic conditions presently associated with Magellanic Moorland, its occurrence in Chiloé at low elevations during the late Pleistocene implies a decrease in average temperature of at least 4°C and an increase in annual precipitation of at least 1500 mm.

The isotopic composition of oxygen in freshwater calcareous tufa seems to be a sensitive indicator of past climatic changes. Results of measurements of δc18O and δc13C in tufa samples dated with the 14C method are used to reconstruct Holocene climatic changes in southern Poland. Values of δc18O obtained on tufa samples from four sites (Raclawka, Rzerzuŝnia, Trzebienice, Sieradowice) representing different hydrodynamic conditions of tufa sedimentation seem to form a selfconsistent series. These values, with some simplifying assumptions concerning the course of tufa sedimentation, were therefore used to estimate mean annual temperatures in the interval ca. 9500-2000 yr B.P. When the resulting curve of thermal changes in southern Poland is compared with changes of deposition and erosion of tuffaceous sediments and with results of other methods of reconstruction of paleoclimate in central Europe, a reasonable agreement among the different specific methods is seen.

A postglacial core was taken from Lily Lake, a soft-water lake, located on carbonate-poor till in eastern Minnesota. Pollen analysis allowed the reconstruction of watershed vegetation change. Diatom assemblages from the core were compared with 255 surface sediment assemblages from Minnesota, Maine, Labrador, and the Canadian arctic. Late-glacial assemblages were similar to Canadian arctic lakes. During the mid-postglacial period of warmer and drier climate, fossil diatom assemblages at Lily Lake were similar to those in the surface sediment of modern eutrophic hardwater lakes in Central Minnesota. The shift to hardwater diatom assemblages coincided with a shift to prairie species in fossil pollen assemblages at about 8000 yr B.P. At about 3400 year B.P. the fossil diatom assemblage that characterized presettlement times was established.

Three lithologically distinct alluvial units of Holocene age can be distinguished along trenched cross sections of the Missisquoi valley bottom. The oldest is of early Holocene age, and the associated floodplain had aggraded to nearly its present level by 8000 14C yr B.P. At that time, early Archaic projectile points were deposited in a fire hearth 50 cm below the surface. Abandonment of this floodplain was followed by the development of an A-E-Bt soil profile. Accumulation of a younger floodplain had begun by 6400 14C yr B.P. and local sedimentation persisted to ca. 500 14C yr B.P., as indicated by radiocarbon dates of buried woody debris (including large logs) and of charcoal. Alluvium of the modern floodplain began accreting after A.D. 1860 and contains machine-cut square nails, whiteware ceramics, and coal clinker. Previous locations of the river channel can be reconstructed from relict surfaces marked by paleosols, the preserved depositional stratigraphy, and the radiocarbon samples. Immediately after regression of the Champlain Sea from this part of the valley, and before 8000 14C yr B.P., the river incised late Fleistocene marine silts and clays at an average rate of at least 1 m/100 yr. After the interval of downcutting, episodic lateral migration became the dominant process, with the rate varying between 0 and 4 m/100 yr. The early Holocene incision was most likely a lagged response to postglacial crustal rebound, whereas strong soil development and floodplain stability between 8000 and 6400 14C yr B.P. may reflect an independently documented warmer, and perhaps drier, climate in New England at this time. Finally, the post-A.D. 1860 period of active floodplain sedimentation may have been a response to timber clear-cutting, row crop agriculture, and cattle and sheep grazing in the watershed.

The chemical composition of ice containing tephra (volcanic ash) layers in 22 sections of the Byrd Station ice core was examined to determine if the volcanic eruptions affected the chemical composition of the atmosphere and precipitation in the vicinity of Byrd Station. The liquid conductivity, acidity, sulfate, nitrate, aluminum, and sodium concentrations of ice samples deposited before, during, and after the deposition of the tephra layers were analyzed. Ice samples that contain tephra layers have, on average, about two times more sulfate and three to four times more aluminum than nonvolcanic ice samples. The acidity of ice samples associated with tephra layers is lowered by hydrolysis of silicate glass and minerals. Average nitrate, sodium, and conductivity are the same in all samples. Because much of the sulfur and chlorine originally associated with these eruptions may have been scavenged by ash particles, the atmospheric residence time of these volatiles would have been minimized. Therefore the eruptions probably had only a small effect on the composition of the Antarctic atmosphere and a negligible effect on local or global climate.