Comparison of the glacial and periglacial deposits and soils of the Alps and Rocky Mountains suggests the following correlations. The Donau, Günz, and Mindel are correlated with the Washakie Point (Nebraskan), Cedar Ridge (Kansan), and Sacagawea Ridge (Illinoian). These glaciations are separated and followed by interglacials represented by thick deeply weathered soils, the last being the Mindel/Riss, or Sacagawea Ridge/Bull Lake (Sangamon). The Riss I (Paar) and Riss II (type Riss) Glaciations are correlated with the early and late advances of the Bull Lake Glaciation (early Altonian), and are believed to be different glaciations separated and followed by short interglacials represented by soils of intermediate development at these latitudes. The Alt-Würm period of restricted ice in the Alps is represented only by local unnamed deposits in the Rocky Mountains. In the Alps, at least three interstadial soils occur between the Riss/Würm soil and the oldest Main Würm end moraine. These coincide in time respectively with the beginning and end of the Port Talbot II interstadial and with Plum Point interstadial. The three major end moraines of the Main Würm are correlated with three or locally more end moraines of the early and middle stades of the Pinedale (Woodfordian). Moraines of the late stade of the Pinedale are equivalent to the late glacial and early postglacial moraines of post-Würm but pre-Atlantic age in the Alps.

K-Ar dating and tephrochronology in the Rockies suggest that the Washakie Point ended about 1.2 m.y. B.P., the Cedar Ridge about 700,000 B.P., the Sacagawea Ridge about 180,000 B.P., the last great interglacial about 130,000 B.P., and the interglacial separating early and late Bull Lake about 80,000 B.P. Radiocarbon dates from the Alps suggest that the Riss/Würm was about 70,000–60,000 B.P., and that Alt-Würm interstadials occurred at >50,000, 45,000–40,000, 34,000–32,000, and 28,000 B.P. Radiocarbon dates from rock shelter deposits in France indicate minor interstadials in the Main Würm at 21,000–20,000 B.P. and about 17,000 B.P. Both the Main Würm and Pinedale ended about 11,800 B.P.

The prevailing surface temperatures in summer and winter at several different stages of the last ice age, indicated at various points scattered over the Northern Hemisphere, by botanical, glaciological, marine biological, oceanographic, etc. evidence, are used to derive probable distributions of 1000−500 mbar thickness, roughly equivalent to mean temperature of the lowest 5 km of the atmosphere and indicating the general flow pattern of the atmosphere in depth. From these thermal wind patterns computation of the tendency to cyclonic and anticyclonic development is possible. Maps of this development field, taken together with the indicated steering of surface cyclones and anticyclones by the thermal winds, make it possible to sketch probable distributions of surface pressure (and, by implication, surface winds) prevailing during each of the glacial stages studied. New light is thrown on the onset of glaciation and on the regimes associated with the maximum extent of glaciation, with the Alleröd warm epoch and the Post-Alleröd cold stage when there was some readvance of the ice.

It is becoming increasingly apparent that the pattern of early human occupation of the Southwestern United States was strongly influenced by the major paleoclimatic events of the period 9500 B.C. to A.D. 700. The size of human populations and the distribution of human settlement at both the regional-topographic and large-scale areal level, known from archaeological research, are directly correlated to climatic change documented by the evidence of geology and palynology.

The effect of climatic change is felt through the actions and reactions of the economic subsystem and its linkages with other subsystems. These reactions reflect not only the character of the climatic stimulus but also the existing state of the cultural system. Alternate reactions include direct systemic readaptation to the changed environment (through changed technologies, methods of population control, etc.); or small scale or large scale relocation of populations in different local niches, regions, or areas whose character most closely approximates the conditions to which the cultural system was initially adapted.

The most commonly used criteria in marine sediments for detecting climatic changes are the remains of organisms and the position of the shorelines, for these two types of criteria can have a relatively quick response to climatic change. The inorganic components of marine sediments, however, also provide useful criteria. On the inner continental shelf where the best correlation should be found between modern terrigenous marine sediments and modern climates, sediment texture is the main criterion. Where land ice reaches the sea, gravel may be deposited, but much of the inner shelf in polar climates receives abundant mud, containing a small amount of clay minerals. From tropical humid climates abundant mud is delivered composed mainly of clay minerals, but knowledge of their composition is required, because the largest rivers do not have a dominance of tropical sediment products. In arid climates and midlatitude moderate rainfall climates, inner shelf sand is indicative, although it also possibly reflects the common entrapment of mud in estuaries and the presence of the middle latitude cyclone belt in which storms remove the fine material present on the inner shelf. Climate also controls extensive carbonate deposits. In deep-sea sediments composition contains more important criteria than texture. Some criteria appear to be reliable for various aspects of modern climates and therefore should be useful in detecting climatic changes. These criteria include the size, surface texture, and mineralogical and chemical composition of eolian transported material downwind of arid lands; global dust in latitudinal bands of atmospheric circulation; volcanic ash downwind of geologically instantaneous events; surface texture of quartz grains and the abundance of terrigenous material in pelagic sediments as indication of glaciation; chlorite from a polar climate; kaolinite from a tropical climate, and inorganically precipitated calcium carbonate in enclosed seas. Less definitive criteria are possibly the rate of turbidity current activity, iron-rich layers in the sediment, sedimentation from the nepheloid zone, construction of features by bottom currents, organic matter content, and sedimentation rate. Speculations include the intensity of benthic faunal reworking of sediment. Using these criteria it is possible to identify the sediment products of the extreme climates: polar, tropical rainy, and dry (desert), and thereby to infer the existence of these climates. The moderate climates apparently are not so easily detected. The criteria also indicate the nature of the water, wind, and ice processes delivering the sediment products to the sea. Extreme values in the frequency or magnitude of the climate-associated processes have great significance in the supplying of terrigenous material, and changes in these extreme values could produce salient changes in the sedimentary sequence. The criteria of climatic change might well be considered criteria of change in extreme values of the processes.

“Thermokarst” as a process is the melting of ground ice and the consequent formation of depressions. Thermokarst landforms depend on the tectonic regime of a region, the ground ice content, and the degree to which the permafrost equilibrium is disturbed. Thermokarst forms are especially prominent in the lowlands of the subnival region with permafrost. The authors distinguish two modes of thermokarst development—permafrost back-wearing and down-wearing—based on their investigations in Siberia. The first mode is characteristic of a more dissected relief. In this case permafrost back-wearing takes place and the process is characterized by development of gullies, thermocirques, and parallel retreat of steep walls with ice veins, resulting in a lower lowland level. The second mode of thermokarst development is due to permafrost melting from above and is typical of a flat undissected relief, mainly that of watershed regions. characteristic forms are depressions with steep slopes and flat floors (alases). Thermokarst valleys develop through coalescence of alases. Thermokarst processes destroy the lowland relief of large areas and create characteristic forms resulting in a lower lowland level. Thus thermokarst represents a special type of lowland development in permafrost conditions.

Biotite-bearing chalky-white rhyolitic ash, here called the Bishop ash bed, occurs in-middle Pleistocene alluvial and lacustrine deposits at eight localities scattered from California to Nebraska and is correlated with the basal air-fall lapilli of the Bishop Tuff, an ash flow of eastern California, radiometrically dated about 0.7 million years. Correlation of the Bishop ash bed with the air-fall lapilli is made on the basis of similar petrography and on chemistry as determined by electron microprobe, atomic absorption, and emission spectrographic analyses. At five localities the Bishop ash bed lies stratigraphically below a Pearlette-like ash. As more occurrences of the Bishop ash bed are found, it should become an increasingly important dated stratigraphic marker relating middle Pleistocene deposits and events across several geomorphic provinces.

Another biotite-bearing chalky-white ash, here called the ash of Green Mountain Reservoir, occurs at three other localities and is distinguishable from the Bishop ash bed by small differences in chemical composition of the glass. The ash of Green Mountain Reservoir is younger than the Bishop ash bed, as shown by the fact that at one locality it lies stratigraphically above the aforementioned bed of Pearlette-like ash.