The same model previously used to deduce an acceptable first order picture of the present zonally averaged macroclimate is now solved for the climatic response to the “glacial” surface boundary conditions that prevailed at 18,000 BP in the northern hemisphere. The equilibrium solution obtained gives the distributions with latitude of the mean temperature, wind, humidity, precipitation, evaporation, heat balance, transient baroclinic eddy statistics (i.e., kinetic energy of the meridional wind and meridional flux of heat, momentum, and water vapor), and the energy integrals. In general terms, the solution shows the glacial atmosphere to be colder and drier than at present, with an intensified polar front, stronger mean zonal and poloidal winds, more intense transient baroclinic eddies (storms) transporting heat, momentum and water vapor poleward at higher rates, and reduced precipitation and evaporation. Also evident is an equatorward shift of the climatic zones (as delineated by the mean surface zonal winds, the poloidal motion, and the difference between mean evaporation and precipitation), particularly in higher latitudes. Other properties of the solution, such as the effect of zonal wind changes on the length of the day, are discussed.

A study area in an arid region of southern New Mexico is in basin-and-range topography and includes both a river valley and a closed basin. Holocene soils occur in valley fills and low terraces between Pleistocene fans, in and near drainageways on the fan-piedmont, on ridges, and in dunes. Holocene soils suggest the character of initial development in soils that are much older and more complex, and record the beginnings of various soil horizons. Noncalcareous brown or reddish brown B horizons have formed in low-carbonate parent materials of stable sites. Incipient development of the argillic horizon and the Haplargids occurs at stable sites in very gravelly materials that are about 1–2000 yr old. The cambic horizon and Camborthids occur in adjacent low-gravel materials of the same age. The argillic horizon occurs continuously in soils of earliest Holocene, particularly in very gravelly materials. Where soils have been truncated, as in areas affected by landscape dissection, argillic and cambic horizons are usually absent and the soils are Torripsamments, Torriorthents, or Torrifluvents depending on content of sand, gravel, and organic carbon. In high-carbonate parent materials, noncalcareous, reddish brown B horizons have not formed at any time in the Holocene. Most of these soils are Torriorthents or Torrifluvents although an incipient calcic horizon has formed in some of the oldest Holocene soils; the latter are Calciorthids. Horizons of carbonate accumulation are the best and most common pedogenic indicators of soil age. Stage I carbonate horizons are a major feature of pedogenesis in the Holocene. Because of additions of carbonate from the atmosphere, carbonate horizons are morphologically similar whether they have formed in high or low-carbonate alluvium. The carbonate accumulations are illuvial.

Some Holocene deposits apparently resulted from changes in climate. Others, such as the youthful deposits of coppice dunes, apparently were caused by man's introduction of cattle and subsequent overgrazing and seed dispersal.

We have examined the circulation of the subpolar North Atlantic at 9300 yr BP by using a dispersed layer of silicic volcanic ash as a synchronous horizon. At the level of this datum, we have reconstructed from foraminiferal evidence a geologically synoptic view of seasonal variations in sea-surface temperatures and salinities. The reconstruction defines two oceanic fronts at 9300 yr BP: (1) the meridionally oriented Polar Front bordering the axis of deglacial outflow of Arctic and Laurentide ice and meltwater and (2) a zonal portion of the Subarctic Convergence along 48° N, marking a major confluence between the subtropical and subpolar gyres. The 9300-yr configuration primarily differed from the modern pattern in the more easterly position (by 3°) of the Polar Front and the more southerly (3°) and easterly (5°) position of the Subarctic Convergene. Both fronts had been merged at 18,000 yr BP into the full-glacial Polar Front; at 9300 yr BP, they were approaching the end of a northwestward deglacial retreat toward the modern interglacial positions.

There were two dominant departures at 9300 yr BP from the Earth's modern configuration, both related to deglaciation: the very large Laurentide Ice Sheet still covering eastern North America to 48° N, and the region of cold Arctic/Laurentide deglacial outflow. These two features caused: a more easterly position than now of the region of upper air divergence and lower air convergence downstream from the Ice Sheet and meltwater outflow; a more intense expression of this upper air divergence and lower air convergence over the central portion of the subpolar North Atlantic; and a latitudinally more stable axis of convergence of surface westerlies over this region. These factors apparently caused the stronger oceanic convergence along 48°N than at present. They also created a stronger, southeastward-directed wind drift current, which opposed the meridional (northward) flow typical of the present interglaciation.

Archeological evidence from the USSR suggests that cultural adaptations to the most rigorous (most continental) environments of northern Eurasia were not achieved until 35–40,000 BP. This presumably sets an absolute basement date for the entry of man into Alaska through the region of Beringia. The absence of evidence for pre-14,000 yr old man in the 48 adjacent United States comparable in any sense to the evidence that has been developed for man prior to 14,000 y.a. in the Old World suggests that movement south out of Alaska only occurred after 14,000 BP.

By mapping and summarizing 478 pollen counts from surface samples at 406 locations in eastern North America, this study documents the relationships between the distributions of pollen and vegetation on a continental scale. The most common pollen types in this region are pine, birch, oak, and spruce. Maps showing isopercentage contours or isopolls for 13 important pollen types reflect the general N-S zonation of the vegetation. The maps and tabulations of average pollen spectra for the six major vegetational regions indicate high values for the following pollen types in each region: (1) tundra-nonarboreal birch, sedge, and alder; (2) forest/tundra-spruce, nonarboreal birch and alder; (3) boreal forest-spruce, jack pine (type), and arboreal birch with fir in the southeastern part; (4) conifer/hardwood forest-white pine, arboreal birch, and hemlock with beech, maple, and oak in the southern part; (5) deciduous forest-oak, pine, hickory, and elm, with beech and maple in the northern part, and highest values of oak and hickory west of the Appalachian crest; and (6) southeastern forest-pine, oak, hickory, tupelo, and Myricaceae. In some cases, less abundant pollen types are diagnostic for the region, e.g., bald cypress in the southeast. In the conifer-hardwood region and southward, pollen of weeds associated with deforestation and agriculture is abundant. The maps also show that much of southeastern U.S. and the area just to the east of Hudson Bay are in need of additional sampling. At 51 of the sites, absolute pollen frequencies (APF; grains/ml lake sediment) were obtained. These confirm the major conclusions from the percentage data, but differences are evident, e.g., the percentages of alder pollen peak in the tundra whereas alder APFs peak in the boreal forest, and spruce percentages peak in the forest-tundra whereas spruce APFs peak in the boreal forest. Because the APF data reflect the patterns of absolute abundance of individual taxa in the vegetation as well as the overall forest densities, future counts of modern pollen should include APF determinations. The effects of sedimentation processes on APF quantities indicate that APF samples should be obtained from moderate size lakes of similar morphology and hydrology and that, in each lake, several samples from the profundal zone should be pooled to create a sample representative of that lake.

Pollen influx and percentage diagrams were prepared from an 11.4 m core from Moulton Pond, Maine. The pond basin was deglaciated about 14,000 y. a., after which it was located on an island in a sea of subarctic character until about 12,400 y. a. when the surrounding area emerged from the sea. The terrestrial vegetation was tundra until about 10,000 y. a. A change in the tundra vegetation is synchronous with the emergence from the sea, but synchroneity with the Pineo Ridge glacial readvance, which reached its maximum 50 km to the east of the pond about 12,700 y. a., is also possible because of imprecision in the dating. Comparisons of the Moulton Pond results with late-glacial pollen sequences elsewhere in eastern United States and adjacent Canada reveal a lack of synchroneity in vegetational changes casting doubt on claims of major broad-scale climatic shifts over the entire area.

The tundra period at Moulton Pond ended with a transition of a few hundred years to partly open, relatively xeric forests of low diversity dominated by white pine, oak, and birch trees. There was no intervening boreal forest. In the postglacial period the vegetation was continually changing, including in the early portion a series of immigrations of temperate tree taxa which later became important in the forests. The transient nature of these assemblages is further indicated by their differences from the closest modern analogs. From about 7100 y. a. until settlement by Europeans 200 y. a., the forests were closed. A major decline of conifers centering about 4700 y. a. was followed by maxima of mesic hardwoods about a thousand years later. In the most recent 2000 yr, the pollen record suggests greater environmental severity, evidenced by increasing spruce. But for the entire postglacial period, the closest modern vegetational analogs are all in the conifer-hardwood region. Much of the postglacial pollen sequence is inexplicable in climatic terms, as evidenced by nonsynchronous behavior of hemlock and beech.

The pollen influx diagram is useful for distinguishing tundra from forest, but for the postglacial period it is difficult to interpret. Pollen influx data are strongly affected by shifts in the pattern of sedimentation in lakes. We propose that such shifts account for the major changes in influx in mid- and late-postglacial time at Moulton Pond and at Rogers Lake, Connecticut. This complicates the interpretation of influx data which otherwise are superior to percentage data.