The chromosomes of Ovis nivicola, described for the first time, exhibit 2n = 52, the lowest diploid number to be reported for wild sheep and goats. The new chromosomal data, together with a review of the fossil history of the genus, lead us to conclude that the bighorned wild sheep (subgenus Pachyceros) evolved their distinctive characteristics while isolated in the ice-free Beringian refugium, and then migrated southward into western North America when the glacial barriers melted, as first suggested by Cowan (1940).

It is proposed that the two preferred modes of temperature and circulation of the atmosphere which occurred over the past 100,000 yr correspond to two modes of partitioning of the poleward energy flux between the atmosphere and ocean. At present the ocean carries an appreciable fraction of the transport, for example about three-eighths at 30°N. In the cold mode it is suggested that the ocean carries less, and the atmosphere more, than at present. During the formation of the ice, at 50,000 BP, for example, the overall flux is expected to be slightly lower than at present and during melting, at 16,000 BP, slightly higher. The transition between the modes is seen as a natural imbalance in the atmosphere-ocean energy budget with a gradual warming of the ocean during an Ice Age eventually cluminating in its termination. At the present the imbalance is thought to correspond to a natural cooling of the ocean, which will lead to the next Ice Age.

The magnitude of temperature changes in the polar regions differ between the hemispheres in the same way as present seasonal changes, being larger in the northern than in the southern hemisphere.

Overall the atmospheric energy cycle was more intense during the Ice Ages than now.

Observational tests are proposed by which predictions from the present arguments may be compared with deductions about the environment of the past.

Data used for the present state of the atmospheric general circulation are the latest global data available and contain no known major uncertainties. However, data for the oceanic circulation and energy budget are less well known for the present and almost unknown for the past. Hence the proposed imbalances must be treated as part of a speculative hypothesis, but one which eventually may be subject to observational test as no solar variability is invoked.

Evidence of (at least) five rapid hemispheric coolings of about 5°C during the last 105 yr has been found, each event spread over not more than about a century, as examples of a global-scale climatic intransitivity. Only some of them lead to a complete glaciation at the northern continents, others ended after a few centuries by a sudden warming (“abortive glaciation”). Starting from a modified version of Wilson's hypothesis of Antarctic ice surges, an air-sea interaction model with realistic geophysical parameters is outlined to interpret the sudden initiation of the North American ice sheet. Special attention is given to the Atlantic section, where the climatic anomalies during the last glaciation appear to have been significantly larger than in other sections.

Isostatic response of the Earth to changes in Quaternary Times of ice and water loads is partly elastic, and partly involves viscous mantle flow. The relaxation spectrum of the Earth, critical for estimation of the mantle flow component, is estimated from published determinations of Fennoscandian and Laurentide rebound, and of the nontidal acceleration of the Earth's rotation. The spectrum is consistent with an asthenosphere viscosity around 1021P, and a viscosity around 1023P below 400 km depth. Calculation of relaxation effects is done by convoluting the load history with the response function in spherical harmonics for global effects, and in rectangular or cylindrical transforms for smaller regional effects. Broad-scale deformation of the globe, resulting from the last deglaciation and sea level rise, is calculated to have involved an average depression of ocean basins of about 8 m, and mean upward movement of continents of about 16 m, relative to the center of the Earth, in the last 7000 yr. Deflection in the ocean margin “hinge zone” varies with continental shelf geometry and rigidity of the underlying lithosphere: predictions are made for different model cases. The computational methods is checked by predicting Fennoscandian and Laurentide postglacial warping, from published estimates of icecap histories, with good results. The depth variations of shorelines formed around 17,000 BP (e.g., North America, 90–130 m; Australia, 130–170 m), are largely explainable in terms of combined elastic and relaxation isostasy. Differences between Holocene eustatic records from oceanic islands (Micronesia, Bermuda), and continental coasts (eastern North America, Australia), are largely but not entirely explained in the same terms.

Disagreement on the time of the end of the Last Interglacial stems from lack of an agreed definition of an Interglacial. Although strictly a climatic episode, “Interglacial” as commonly used is essentially a chronologic unit equivalent to an Age, corresponding in time range to the chronostratigraphic unit Stage.

The name “Last Interglacial” has gained a global connotation so that its definition must take into account global rather than local effects of temperature fluctuations. An Interglacial begins with a warming to full interglacial warmth (as warm as the present day). It continues until a cooling of full glacial severity occurs, and includes any lesser coolings within a period of fluctuating climate. Such lesser coolings are recorded, particularly in deep-sea cores, following a period of warmth about 125,000 y.a. The cooling that led to the next full glacial cold began about 50,000 yr later. The Last Interglacial lasted from about 128,000 to 73,000 yr BP, equivalent to stage 5 of Shackleton and Opdyke.

Departures of mean annual precipitation and temperature for the decade 1961–1970 from the 1931–1960 averages are illustrated on maps of the tropical and subtropical portions of the American continents. Certain features of midlatitude climatic anomalies appear to be associated with concurrent anomalies in the tropics. There is an apparent southward shift of circulation features in this longitudinal sector of both hemispheres. A review of selected literature on latitudinal climatic shifts and atmosphere-ocean interaction suggests some similarities between the patterns of climate in the 1960s and the climate of the Little Ice Age.

Monitoring evidence indicates that the Holocene embraced a sequence of rather discrete climatic episodes. The transitions between these environmental episodes apparently were abrupt and globally synchronous. This paper reports on statistical analyses of radiocarbon dates associated with environmental change and cultural change.

Over 800 14C dates associated with pollen maxima and minima, sea level maxima and minima, and top and bottom surfaces of peat beds were simultaneously analyzed to identify times of globally synchronous environmental discontinuities.

Some 3700 14C dates associated with 155 cultural continua of the world were collectively analyzed to identify worldwide synchroneities in appearance and termination of the cultures.

Significant globally synchronous discontinuities were identified in each independent analysis. The dates of environmental and cultural discontinuities are rather similar, particularly during the recent half of the Holocene. The fact that the cultural discontinuities mostly follow rather closely those of the paleobotanical record suggests that there has been a distinct climatic impact on the cultural history of man.

Mean monthly temperatures for the Northern Hemisphere were determined for the years 1955 through 1968 following the same procedures used by H. C. Willett and J. M. Mitchell, Jr., in their studies of long-term trends. It was found that the downward trend they reported starting in the 1940s continued, though interrupted, into the 1960s.

The temperature data when combined with radiation data and other components of the hemispheric energy budget led to the formulation of the response ratio, the relationship between change in incoming solar radiation and change in temperature. When this response ratio was applied to the reported trends in direct solar radiation and to the decrease in direct solar radiation following the eruption of Agung in 1963, a probable cause-effect relationship was suggested.

Analyses of crystal size, bubble content, oxygen isotope ratio, specific electrolytic conductivity, and the distribution of firn and dirt layers in a core, 121.2 m long, from surface to bedrock near the highest point of the Meighen Ice Cap, leads to the following outline of the ice cap's history. The ice cap, which has always been stagnant, originated in the cold period that followed the postglacial Climatic Optimum. After initial growth came a period of negative mass balance in which the area and thickness of the ice cap diminished and the surface slope at the core site steepened. The end of this period, at least 600 y.a., is marked by a discontinuity at 54 m depth in the core; above this level, the values of most parameters differ significantly from their values below. There followed a period of growth by the end of which, some 80 y.a., the ice cap had attained its maximum thickness; this period included the coldest interval in the ice cap's history. Ablation has predominated since then and up to 13 m of ice have been lost at the core site. This history resembles that of the Ward Hunt Ice Shelf.

The position of the Inland Ice margin during the late Wisconsin-Würm glaciation (ca. 15,000 yr BP) is probably marked by offshore banks (submarine moraines?) in the Davis Strait. The history of the Inland Ice since the late Wisconsin-Würm can be divided into four principal phases: (1) Relatively slow retreat from the offshore banks occurred at an average rate of approximately 1 km/100 yr until ca. 10,000 yr BP (Younger Dryas?) when the Taserqat moraine system was formed by a readvance. (2) At ca. 9500 yr BP, the rate of retreat increased markedly to about 3 km/100 yr, and although nearly 100 km of retreat occurred by ca. 6500 yr BP, it was punctuated by frequent regional reexpansions of the Inland Ice that formed extensive moraine systems at ca. 8800-8700 yr BP (Avatdleq-Sarfartôq moraines), 8400-8100 yr BP (Angujârtorfik-Fjord moraines), 7300 yr BP (Umîvît moraines), and 7200-6500 yr BP (Keglen-Mt, Keglen moraines). (3) Between 6500 and 700 yr BP, discontinous ice-margin deposits and ice-disintegration features were formed during retreat, which may have continued until the ice margin was near or behind its present position by ca. 6000 yr BP. Most of the discontinuous ice-margin deposits occur within 5–10 km of the present ice margin, and may have been formed by two main phases of readvance at ca. 4800-4000 yr BP and 2500-2000 yr BP. (4) Since a readvance at ca. 700 yr BP, the Inland Ice margin has undergone several minor retreats and readvances resulting in deposition of numerous closely spaced moraines within about 3 km of the present ice margin. The young moraines are difficult to correlate regionally, but several individual moraines have the following approximate ages: A.D. 1650, 1750, and 1880–1920.

Inland Ice fluctuations in West Greenland were very closely paralleled by Holocene glacial events in East Greenland and the eastern Canadian Arctic. Such similarity of glacier behavior over a large area strongly suggests that widespread climatic change was the direct cause of Holocene glacial fluctuations. Moreover, historical advances of the Inland Ice margin followed slight temperature decreases by no more than a few decades, and 18O data from Greenland ice cores show that slight temperature decreases occurred frequently throughout the Holocene. Therefore, we conclude that construction of the major Holocene moraine systems in West Greenland was caused by slight temperature decreases, which decreased rates of ablation and thereby produced practically immediate advances of the ice sheet margin, but did not necessarily affect the long-term equilibrium of the ice sheet.

This paper evaluates the geological and paleoecological implications of a Wenner-Gren symposium Stratigraphy and Patterns of Cultural Change in the Middle Pleistocene. The deep-sea, glacial-eustatic, loess, alluvial, and palynological records suggest between six and eight cold-warm cycles since the Brunhes-Matuyama magnetic reversal of 700,000 BP. Till and outwash stratigraphies are inadequate to provide a valid nomenclature for the numerous glacials preceding the Würm. Since at least five of the glacials since 700,000 BP were sufficiently severe to produce permafrost in midlatitude Europe, the “glacial Pleistocene” begins with the Brunhes-Matuyama. Although earlier cold-warm cycles extend well back into the early Pleistocene, with extensive glaciation and repeated floral decimations in higher latitudes, the first record of permafrost in the Rhine Basin 700,000 BP argues that major climatic oscillations of the Brunhes epoch were of glacial-interglacial amplitude. It is therefore recommended that a Lower-Middle Pleistocene boundary be linked to the practicable and universally applicable chronometric horizon provided by the Brunhes-Matuyama reversal, while the Middle-Upper Pleistocene limit can continue to be drawn at the base of the last, Eemian Interglacial (130,000 BP). The tropical African record presently contributes little to general understanding of the Middle Pleistocene, while the climatic cycles of higher latitudes are of limited value in analyzing mid-Pleistocene records of the tropical continents. Problems of stratigraphic control and environmental contexts for archeological sites are discussed.

Since chronometric data comparable to that available from the late Cenozoic succession of East Africa have not, and probably cannot be obtained in southern Africa, faunal dating methods retain their traditional significance in the latter area. Five successive late Cenozoic mammal ages, the Namibian, Langebaanian, Makapanian, Cornelian, and Florisian have been proposed as a framework for discussions relating to the chronology of southern African mammalian faunas. The Namibian fauna is poorly known, but is evidently of Miocene age. It is not discussed in this paper. The Langebaanian fauna is well known only from the prolific occurrence at the type site of Langebaanweg and is Pliocene in age. Makapanian faunas are best represented at the Transvaal Australopithecine sites and probably overlap the Plio-Pleistocene boundary. The Cornelian fauna is not as well known as others, the largest assemblage having been recorded from Elandsfontein, although this assemblage is one which is unfortunately temporally heterogeneous. Florisian faunas have been recovered from a relatively large number of localities, including several for which there are radiometric dates. The recorded southern African fossil Carnivora are listed and the local evolution of this group is discussed in terms of the mammal age chronology. It is concluded that secure faunal dating of individual fossil occurrences is enhanced by an appreciation of the nature of changes undergone in evolutionary lineages, while an uncritical knowledge of recoreded taxa is less useful.

Geologic evidence in the closed Seistan Basin of southwestern Afghanistan and adjacent parts of Iran and Pakistan indicates that a lake as much as 65,000 sq km in size occupied this closed depression during Pleistocene time. The deposits consist mostly of lacustrine silt and clay and have a maximum observed thickness of about 250 m. A layer of alluvial gravels overlies the sequence. The deposits are probably early or middle Pleistocene in age; they are old enough to have sustained nearly 300 m of erosion over large areas but are not faulted or detectably folded in the central part of the basin although they are upwarped along the west edge of the basin.

Sand dunes cover extensive areas of the basin. Dune orientation shows that the strong surface winds enter the basin blowing toward the south-southeast and then are deflected to the east, apparently as a response to mountains bordering the basin on its south side. The Gawdezereh, a large deflation depression, may be a result of an augmented excavation ability of winds that occurs where turbulence is created along a zone of deflection.

Late-Quaternary sea level changes in the eastern Aleutian Islands are of paramount importance in the reconstruction of the migrations and environment of the ancient Aleuts. A radiocarbon-dated ash stratigraphy provides the chronology into which geomorphic events can be fitted. These provide evidence for the sea level changes. Deployment of beach material and coastal configuration intimate that sea level was about 2–3 m above the present level about 8250 radiocarbon yr BP. Beach deposits suggest that sea level remained high until about 3000 radiocarbon y.a. when it gradually dropped to its present position. It is concluded that the ancient Aleuts that settled Anangula about 8400 y.a. used boats; all major passes in the eastern Aleutians were flooded, and did not have winter ice. Those ancient Aleuts did not have available the major year-around food resources of the present strandflats as they were cut during the high sea level stand 8250–3000 yr BP. The ancient Aleuts must have been marine oriented, for land-based food resources would have been limited.

The cause of relative sea level changes on Umnak Island is considered indeterminate with present data. Eustatic, glacial isostatic, water isostatic, tectonic, and volcanic causes are considered the main possible controls in combinations such that a basic eustatic sea level curve and likely a glacial-water isostatic curve must be common to any solution. Representative solutions are given to illustrate some of the problems.

Cover sediments of the York Terrace exposed near the California River, western Seward Peninsula, Alaska, yield mollusks, ostracodes, and foraminifera that lived during the Anvilian transgression of early Pleistocene age. The fossiliferous sediments lie at the inner edge of the York Terrace, a deformed wave-cut platform that extends eastward from Bering Strait along much of the southern coast of Seward Peninsula. The seaward margin is truncated by the little-deformed Lost River Terrace, carved during the Pelukian (Sangamonian) transgression. The early Pleistocene sediments seem to have been deposited between the first and second of four glaciations for which evidence can be found in the California River area.

The California River fauna includes several extinct species and several species now confined to areas as remote as the northwestern Pacific and north Atlantic. The fauna probably lived in water temperatures much like those of the present time but deeper water on the Bering Shelf is suggested.

The presence of an early Pleistocene fauna at the inner edge of the York Terrace at California River shows that the terrace was largely carved before and during early Pleistocene time. However, a marine fauna apparently of middle Pleistocene age is found on the York Terrace near Cassiterite Peak, and this seems to indicate that the terrace remained low until middle Pleistocene time. Uplift of the York Terrace probably was accompanied by uplift of Bering Strait. The strait may have been deeper, and there may have been no land bridge between the Seward Peninsula of Alaksa and the Chukotka Peninsula of Siberia during most of early and middle Pleistocene time.

Parallel to the Essex coast north of the mouth of the Thames, a series of gravel spreads ranging in altitude from near sea level westward to more than 200 ft O.D. (mean sea level) proved to be the remnants of an abandoned Thames/Medway terrace system, rather than a series of “raised” beaches, as their location had suggested. The seaward side of the ancient river valley has subsequently been “captured” by subsidence.

Evidence is given for five terraces, with surface levels between 5 and 75 ft O.D. Because of subsidence of the Essex coast, the terrace levels are not easily correlatable with either the Thames or Medway terrace levels. Temporal placement is attempted on the basis of one site in the 25 ft Barling terrace, which yielded a Middle Acheulian archaeological assemblage associated with a cool temperate fauna including an early form of mammoth. An ice wedge cast in the Barling terrace was filled with floodloam which weathered to a parabraunerde soil during an interglacial climate warmer than now. For these reasons man is thought to have lived on the floodplain of the Barling terrace either at the onset of the Wolstonian (Riss) glacial or during an interstadial of that stage. The question of possible linkages between Swanscombe and Clacton terraces is discussed.

In an area regarded to be very favorable for the study of Holocene sea level changes one or several eustatic (?) oscillations of sea have been found using sedimentological and ecological methods. After a maximum of +3 m during the Nouakchottian stage (= Middle Flandrian or Late Atlantic) about 5500 YBP a drop of sea to −3.5 ± 0.5 m about 4100 YBP is testified by stromatolitic algae indicating the former sea level within the tidal zone with high accuracy. This evidence is supported by the observation of post-Nouakchottian regressive and transgressive geologic sequences, by buried beach deposits and flooded hardgrounds, post-Nouakchottian marine terraces of different height and age, the cutting off of one large and several small bays from the open sea, etc. Possibly one or two smaller oscillations followed between 4000 and 1500 YBP (derived sea level curve Fig. 3).

Canonical correlation analysis, as described by Webb and Bryson, Quaternary Research 1972, provides a means of reconstructing past climates quantitatively from fossil pollen using a pollen-climate transfer function. This paper presents a method for analysis of variance of the transfer function model. This method is used to identify ecological relationships among the pollen and climate variables, to select climatically sensitive taxa, and to investigate the importance of site factors. Several criteria are presented, in addition to those used by Webb and Bryson, for choosing canonical variate pairs to include in the transfer function model, namely: the variate pair relationships should be ecologically meaningful; the transfer function model should yield stable paleoclimatic estimates; and, the variate pair relationships should be statistically meaningful. The application of these criteria to the set of variate pairs used in the transfer function model of Webb and Bryson is described and modifications are suggested.

An extensive insect fauna is described from an organic deposit occurring in a gravel pit at Lea Marston, Warwickshire, England. This organic deposit was lying beneath approximately 2.5 m of alluvial clay and directly above gravels which had provided organic material 14C dated at 11,700 ± 200 yr BP. The insect fauna was indicative of a temperate oceanic climate similar to that found today in southern England or south Sweden and suggested the presence of deciduous woodland. The six radiocarbon dates, however, agreed in giving the deposit an age of around 9500 yr BP which is earlier than the arrival of the principal broad-leaved trees. The pollen assemblage was consistent with the radiocarbon dates in showing, in addition to herbaceous pollen, only the presence of Betula, Salix, and small amounts of Pinus. As the insect faunas known from midland Britain at the close of the Devensian period, barely 500 yr before, are arctic in aspect and entirely devoid of thermophilous species a very rapid climatic amelioration is postulated which permitted the immigration of the very mobile insect fauna well in advance of the more slowly migrating trees.