CLIMAP (1981, “Seasonal Reconstruction of the Earth's Surface at the Last Glacial Maximum,” Geological Society of America Map and Chart Series MC-36) boundary conditions were used as inputs to the GISS general circulation model, and the last glacial maximum (LGM) climate was simulated for six model years. The simulation was compared with snow line depression and pollen-inferred temperature data at low latitudes, specifically for Hawaii, Colombia, East Africa, and New Guinea. The model does not produced as much cooling at low latitudes as is implied by the terrestrial evidence. An alternative experiment in which the CLIMAP sea-surface temperatures were uniformly lowered by 2°C produces a better fit to the land data although in Hawaii model temperatures are still too warm. The relatively warm CLIMAP tropical sea-surface temperatures also provide for only a slight decrease in the hydrologic cycle in the model, in contrast to both evidence of LGM tropical aridity and the results of the experiment with colder ocean temperatures. With the CLIMAP sea-surface temperatures, the LGM global annual mean surface air temperature is 3.6°C colder than at present; if the ocean temperatures were allowed to cool in conformity with the model's radiation balance, the LGM simulation would be 5°–6°C colder than today, and in better agreement with the tropical land evidence.

Study of the eolian fraction of late Quaternary sediments from the tropical Atlantic reveals that two modes of long-term climate variability have existed in tropical Africa during the last 150,000 yr. Tropical northwest Africa (i.e., the southwestern Sahara and Sahel) was driest during glaciations and stades, but wetter than at present during interglaciations and interstades. This may be a response to ice sheets at higher latitudes, via equatorward displacement of the westerlies and the subtropical high. In contrast, central equatorial Africa (southeast of the Sahara) was most arid during interstades and times of ice growth, and most humid during deglaciation. Wet periods in this area correspond to insolation maxima in northern hemisphere summer. A 23,000-yr precessional rhythm is suggested, supporting a direct link between African Monsoon intensity and orbitally modulated insolation. The late Holocene is the only time observed when both areas are arid during an interglacial episode. This may reflect, in part, anthropogenic disturbance of late Holocene climates.

Geomorphic evidence from the Peruvian-Bolivian Altiplano indicates that during episodes prior to 28,000 and around 12,500-11,000 yr B.P., lakes covered an area about six and four times as large as at present, respectively. Within the constraints of the heat and water budget, model calculations are used to estimate the precipitation rate that would allow hydrologic equilibrium. On this basis it is suggested that rainfall on the Altiplano during the episodes of enlarged lakes was, respectively, some 300 and 200 mm annum−1 larger than at present, representing increases of about 75 and 50%, respectively. Field evidence suggests that the episodes of enlarged lakes on the Altiplano may have preceded or coincided with periods of maximum glaciation in the neigh-boring Andes. In this region with high elevation of the ice equilibrium line, increased precipitation is particularly conducive to glaciation.

The mass accumulation rate and grain size of the total colian component isolated from pelagic sediment in two North Pacific cores, piston core KK75-02 under the prevailing westerlies and Deep-Sea Drilling Project Site 503 beneath the trade winds, have been used to evaluate changes in the intensity of atmospheric circulation and source-area aridity over the past 700,000 yr. The eolian grain size, a direct indicator of wind intensity, fluctuates at periodicities similar to those calculated for the earth's orbital parameters of precession, obliquity, and eccentricity. Both sites display greater variability in wind intensity prior to 250,000 yr ago. Eolian accumulation rates, an indicator of source-area aridity, fluctuate at periodicities similar to those of the glacial-interglacial cycles. Lower eolian accumulation rates during colder (glacial) times most likely reflect increased glacial-age humidity at central Asian and Central American source areas.

The Weichselian deposits of the flat Dutch-Belgian coversand area are characterized by highly varying facies types. The geomorphological location and the role of water during the deposition and the transportation of the original eolian sediments may fully explain the texture and sedimentary structures of the lithostratigraphic units. Directly deposited eolian loams and sands on the dry interfluves contrast with the same, but reworked, sediments in wet valleys and depressions. The formation of periglacial phenomena is also dependent on the geomorphologic, lithologic, and hydrologic conditions. The occurrence of peaty beds is restricted to wet environments without precise climatic significance. The Pleniglacial sequence is subdivided into early and late Pleniglacial stades, both characterized by (partial) permafrost conditions, interrupted by a middle Pleniglacial interstadial complex with clearly milder conditions.

A numerical model was designed to study the stability of a marine ice sheet, and used to do some basic experiments. The ice-shelf/ice-sheet interaction enters through the flow law in which the longitudinal stress is also taken into account. Instead of applying the model to some (measured) profile and showing that this is unstable (as is common practice in other studies), an attempt is made to simulate a whole cycle of growth and retreat of a marine ice sheet, although none of the model sheets is particularly sensitive to changes in environmental conditions. The question as to what might happen to the West Antarctic Ice Sheet in the near future when a climatic warming can be expecied as a result of the CO2 effect, seems to be open for discussion again. From the results presented in this paper one can infer that a collapse, caused by increased melting on the ice shelves, is not very likely.

A model for sedimentation by surging glaciers is developed from analysis of the debris load, sedimentary processes, and proglacial stratigraphy observed at the Icelandic surging glacier, Eyjabakkajökull. Three aspects of the behavior of surging glaciers explain the distinctive landformsediment associations which they may produce: (a) sudden loading of proglacial sediments during rapid glacier advances results in the buildup of excess pore pressures, failure, and glacitectonic deformation of the overridden sediments; (b) reactivation of stagnant marginal ice by the downglacier propagation of surges is associated with large longitudinal compressive stresses. These induce intense folding and thrusting during which basal debris-rich ice is elevated into an englacial position in a narrow marginal zone. As the terminal area of the glacier stagnates between surges, debris from this ice is released supraglacially and deposited by meltout and sediment flows; (c) local variations in overburden pressure beneath stagnant, crevassed ice cause subglacial lodgement tills, which are sheared during surges, to flow into open crevasses and form “crevasse-fill” ridges.

The Sayif travertines and lacustrine limestones cropping out in the northern Arava Valley, a region of extreme aridity, have been dated by the 230Th/234U disequilibrium method. The consistency between the stratigraphic position and the apparent ages at each of the sampling sites strongly supports the reliability of the ages. Most of the ages fall within two clusters that are coincident with ages representative of oceanic oxygen-isotope stages 5 and 7. The colder intervening stage 6 was not a period of substantial travertine formation. During the warmer global episodes of isotopic stages 5 and 7 the arid south of Israel apparently was considerably wetter than at present.

Geomorphic, stratigraphic, palynologic and 14C evidence indicates that the West Coast Range, Tasmania, was glaciated at least three times during the late Cenozoic. The last or Margaret Glaciation commenced after 30,000 yr B.P., culminated about 19,000 yr B.P., and ended by 10,000 yr B.P. During this period a small ice cap, ca. 250 m thick, and cirque and valley glaciers covered 108 km2. The glacial deposits show little chemical weathering or erosional dissection. The snow line ranged from 690 to 1000 m with an average of 830 m for the ice cap. Mean temperature was 6.5°C below the present temperature. During the preceding Henty Glaciation a 300- to 400-m-thick ice cap and outlet glaciers exceeded 1000 km2. The glacial deposits are beyond 14C assay. They are more weathered chemically and more dissected than Margaret age deposits, and the degree suggests a pre-last interglaciation age (> 130,000 yr B.P.). The snow line of the ice cap lay at 740 m, and annual temperature was reduced by 7°C. Ice of the earliest Linda Glaciation slightly exceeded that of the Henty Glaciation but had a similar distribution. The glacial deposits are intensely weathered, have reversed magnetization, and overlie a paleosol containing pollen of Tertiary type. An early Pleistocene or Tertiary age is indicated.

A theory of the world's sea-level fluctuations during late Pleistocene time, based on the analysis of the general equation of the mass balance between ocean water and inland water, suggests that the exchange of water masses between the ocean and the land, where at continental glaciation periods water is stored as ice, occurs only as a result of global climatic changes. The tectonic effect is considered insignificant for late Pleistocene time. The proposed theory explains the asymmetric character and the sawlike shape of the curve of the main cycles of sea-level fluctuations. The theory also makes it possible to construct a diagram of sea-level fluctuations from the last glacial maximum to the present time. This diagram is governed by two parameters, the amount of the average “effective” evaporation from the world's ocean surface (evaporation minus rainfall) and the rate of the sea-level rise at the present time. The resulting theoretical curve agrees well with known estimates of sea level within the time span being considered. The comparison of the theoretical curve with these estimates eliminates the apparent discrepancy between data obtained by different methods: measurements of old coastline and the isotopic composition of bottom sediments.

Pollen and macrofossil analyses of two radiocarbon-dated lake sediment cores in the upper Peace River district were used to investigate the controversial late-glacial geochronology of the “ice-free corridor.” The basal mineral-rich sediments contain reworked, radiogenically “dead” palynomorphs, as well as intrusive “modern” carbon. Analyses of the basal sediments from Boone Lake show that two 14C ages greater than 12,000 yr B.P. are spuriously old due to contamination by organic matter of Cretaceous age. The data support occlusion or near occlusion of Laurentide and Cordilleran ice in the Peace River area during the late Wisconsinan period. The sediment record began around 12.000 yr B.P. in the ice-dammed and enlarged Boone Lake. An initially open, sedge-dominated cover was invaded by sage, willow, grass, and poplar by 11,700 yr B.P., suggesting that a habitable landscape has existed in the area for at least 12 millennia. The data, however, do not support the ice-free corridor arguments of B. O. K. Reeves (1973, Arctic and Alpine Research 5, 1–16; 1983, In “Quaternary Coastlines and Marine Archaeology: Towards the Prehistory of Land Bridges and Continental Shelves” (P. M. Masters and N. C. Fleming, Eds.), pp. 389–411. Academic Press, New York), who suggests that ice occlusion did not occur in the Peace River Valley during the last 55,000 yr.

Using modern pollen and radiolarian distributions in sediments from the northwest Pacific and seas adjacent to Japan to interpret floral and faunal changes in core RC14-103 (44°02′N, 152°56′E), we recognize two major responses of the biota of eastern Hokkaido and the northwest Pacific to climatic changes since the last interglaciation. Relatively stable glacial environments (∼80,000–20,000 yr B.P.) were basically cold and wet (<4°C and ∼1000 mm mean annual temperature and precipitation, respectively) with boreal conijers and tundra/park-tundra on Hokkaido, and cool (<16°C) summer and cold (<1.0°C) winter surface temperatures offshore. Contrasting nonglacial environments (∼10,000–4000 yr B.P.) were warm and humid (>8°C and >1200 mm mean annual temperature and precipitation, respectively), supporting climax broadleaf deciduous forest with Quercus and Ulmus/Zelkova, with surface waters in the northwest Pacific characterized by warm (>1.5°C) winter and cold (10.4°–14.3°C) summer temperatures. Climatic evidence from RC14-103 shows a high degree of local and regional variation within the context of global climatic change. Correlative ocean and land records provide the detailed input necessary to assess local/regional responses to variations in other key elements (i.e., solar radiation, monsoonal variations) of the northeast Asian climate system.

A 14-m-thick section of marine and nonmarine sediments of the Gubik Formation of northern Alaska, exposed in bluffs near Ocean Point on the Colville River, has been studied by means of pollen analysis. Pollen from the marine sediments, of probable late Pliocene age, records a boreal forest of spruce and birch with minor amounts of alder in the adjacent terrestrial vegetation. Pine and perhaps true fir were probably at or near their northern limit here, but hemlocks and hardwoods were absent. The suggested environment for the Arctic Slope during the time represented by the marine sediments is similar to that of present-day Anchorage. Pollen floras from the overlying fluvial strata, of early or middle Pleistocene age, record predominantly herbaceous taxa indicating tundra conditions probably more severe than those of the present day. These deposits were most likely contemporaneous with glacial conditions in the Brooks Range to the south. Pollen of woody taxa (spruce, alder, birch, heaths) is rare through most of the section, although birch and alder percentages similar to those found in modern river sediments indicate an interstadial or interglacial warming in midsection. Inland climates during glacial episodes may have been similar to those of the present Arctic coast.

Cave sediments from Stump Cross Cave in northern England contain Pleistocene mammal remains. Uranium-series dating of calcium carbonate deposits closely associated with the fossiliferous horizons has established an absolute age of 83,000 ± 6000 yr B.P. for a faunal assemblage largely comprised of wolverines (Gulo gulo). This date lies firmly within the younger portion of oxygen-isotope stage 5. The occurrence of wolverines in the vicinity of Stump Cross Cave at ca. 83,000 yr B.P. indicates a significant climatic deterioration from ca. 120,000 yr B.P., when an Ipswichian interglacial fauna with hippopotamus was present in this part of northern England.

Seismic profiles across the southwest end of Jeffreys Ledge, a bathymetric high north of Cape Ann, Massachusetts, reveal two end moraines. The moraines overlie upper Wisconsinan glacialmarine silty clay and are composed mostly of subaqueous ice-contact deposits and outwash. They were formed below sea level in water depths of as much as 120 m during fluctuations of a calving ice front. The moraines are late Wisconsinan in age and were formed after the Cambridge readvance, about 14,000 yr B.P., and before the Kennebunk readvance, about 13,000 yr B.P. They represent fluctuations of the ice front during overall retreat of Laurentide ice from the Gulf of Maine and New England.

A variety of paleoecological and sedimentary techniques were used to investigate the storage of sediment within a small lowland catchment during the Holocene. Radiocarbon dating of vertically accreted floodplain deposits allowed the calculation of inorganic accumulation rates. These rates show a dramatic increase in sediment deposition during the late Bronze Age and early Iron Age (2900-2300 yr B.P.) due to deforestation and cultivation of the catchment slopes and resultant soil erosion. The soils within the catchment were susceptible to structural damage, surface waterlogging, and slope-wash erosion. From the calculated increases in sediment storage estimates of catchment erosion were made which vary from around 20 to 140 tons km−2 yr−1. The study of alluvial chronology at this scale can provide unique information on the source areas of Holocene floodplain sediments and provide long-term erosion rates.

Two sediment cores from Kaiyak and Squirrel lakes in northwestern Alaska yielded pollen records that date to ca. 39,000 and 27,000 yr B.P., respectively. Between 39,000 and 14,000 yr B.P., the vegetation around these lakes was dominated by Gramineae and Cyperaceae with some Salix and possibly Betula nana/glandulosa forming a local, shrub component of the vegetation. Betula pollen percentages increased about 14,000 yr B.P., indicating the presence of a birchdominated shrub tundra. Alnus pollen appeared at both sites between 9000 and 8000 yr B.P., and Picea pollen (mostly P. mariana) arrived at Squirrel Lake about 5000 yr B.P. The current foresttundra mosaic around Squirrel Lake was established at this time, whereas shrub tundra existed near Kaiyak Lake throughout the Holocene. When compared to other pollen records from north-western North America, these cores (1) represent a meadow component of lowland. Beringian tundra between 39,000 and 14,000 yr B.P., (2) demonstrate an early Holocene arrival of Alnus in northwestern Alaska that predates most other Alnus horizons in northern Alaska or northwestern Canada, and (3) show an east-to-west migration of Picea across northern Alaska from 9000 to 5000 yr B.P.

Radiocarbon analysis plays an important role in studying the Quaternary geologic history of the East China Sea. More than 200 14C dates have been published in various Chinese publications. The continental shelf of the East China Sea is one of the few large continental shelves in the world. Many low-lying flats and deltaic plains lie along the coast making it a favorable site for sea-level studies. Radiocarbon data from Neolithic sites, chenier ramparts, peaty deposits, and submarine sediments converge to suggest that oscillations of sea level have occurred: they also suggest that the lowest glacial sea levels probably occurred between 22,000 and 19,000 yr B.P. Calculation of the volume of the Yangtze River Delta, together with 14C dates, indicates that more than 89% of the solid particles carried by the river were deposited in the delta. Due to the sedimentary load, the crust beneath the delta has subsided isostatically and tilted seaward. Marine shells provide many acceptable 14C dates, but because they are easily transported, most samples from the continental shelf cannot be directly related to the history of sea-level changes.

The distribution of radiolarian assemblages identified by Q-mode factor analysis of radiolarian microfossils in surface sediments from low latitudes in the Pacific Ocean reflects their associations with surface water masses. Downcore fluctuations of these radiolarian assemblages at two sites, RC10-65 and V19–29, indicate changes in circulation in the eastern equatorial Pacific during the past 500,000 yr. Surface-water radiolarian assemblages characteristic of zonal flow have dominated siliceous sedimentation in the eastern equatorial Pacific, except during times of intense upwelling which can occur along the coast of Peru and in the Equatorial Undercurrent. Fluctuations in the importance of this upwelling have not been consistent with glacial/interglacial changes in ice volume throughout the late Quaternary. Intensification of upwelling in the equatorial divergence, however, has consistently coincided with increases in ice volume in the past 500,000 yr. The times at which changes in the nature of the relationship between upwelling and ice volume occur (approximately 240,000 and 380,000 yr B.P.) roughly coincide with times of observed changes in other proxy indicators of oceanographic conditions in the Pacific and Indian oceans.

Sediments of Balsam Meadow have produced a 11,000-yr pollen record from the southern Sierra Nevada of California. The Balsam Meadow diagram is divided into three zones. (1) The Artemisia zone (11,000–7000 yr B.P.) is characterized by percentages of sagebrush (Artemisia) and other nonarboreal pollen higher than can be found in the modern local vegetation. Vegetation during this interval was probably similar to the modern vegetation on the east slope of the Sierra Nevada and the climate was drier than that of today. (2) Pinus pollen exceeded 80% from 7000 to 3000 yr B.P. in the Pinus zone. The climate was moister than during the Artemisia zone. (3) Fir (Abies, Cupressaceae, and oak (Quercus) percentages increased after 3000 yr B.P. in the Abies zone as the modern vegetation at the site developed and the present cool-moist climatic regime was established. Decreased fire frequency after 1200 yr B.P. is reflected in decreased abundance of macroscopic charcoal and increased concentration of Abies magnifica and Pinus murrayana needles.