Nine first-appearance datums (FADs), twenty-three last-appearance datums (LADs), and three other micropaleontological datums are related to the magnetic-reversal, oxygen-isotope, and calcite-dissolution/coarse-fraction time scales to provide a preliminary basis for subdivision of the Quaternary in deep-sea sediments. The magnetic-reversal, oxygen-isotope, and calcite-dissolution/coarse-fraction scales have been correlated by determination on the same core materials, and absolute dates applied by 40K/40Ar or 14C dating of materials in known positions on one or another of these scales. FADS and LADs have been determined in cores for which either a magnetic-reversal, oxygen-isotope, or calcite-dissolution/coarse-fraction scale has also been available. Altogether 3 FADs and 5 LADs based on diatoms, 4 FADs and 5 LADs based on calcareous nannoplankton, 1 FAD and 8 LADs based on radiolarians, 1 FAD and 5 LADs based on planktonic foraminifers, 2 acme datums, and 1 ratio reversal datum have been determined, and absolute dates inferred by interpolation from known dates on the reference time scales. Some of the FADs and LADs apply or are synchronous only over limited areas of the oceans; others appear to be synchronous throughout the oceans. The base of the Quaternary is set at the top of the Olduvai event at 1.7 my. Four FADs, twelve LADs, two acme datums, and one ratio reversal datum occur above the base of the Quaternary at an average rate of about 1 per 100,000 yr. Five FADs and twelve LADs are recognized in the 0.8-my interval between the top of the Olduvai event and the Gauss/Matuyama Boundary at 2.5 my at an average incidence of about 1 per 50,000 yr.

During the Vashon Stade of the Fraser Glaciation, about 15,000–13,000 yr B.P., a lobe of the Cordilleran Ice Sheet occupied the Puget lowland of western Washington. At its maximum extent about 14,000 yr ago, the ice sheet extended across the Puget lowland between the Cascade Range and Olympic Mountains and terminated about 80 km south of Seattle. Meltwater streams drained southwest to the Pacific Ocean and built broad outwash trains south of the ice margin. Reconstructed longitudinal profiles for the Puget lobe at its maximum extent are similar to the modern profile of Malaspina Glacier, Alaska, suggesting that the ice sheet may have been in a near-equilibrium state at the glacial maximum. Progressive northward retreat from the terminal zone was accompanied by the development of ice-marginal streams and proglacial lakes that drained southward during initial retreat, but northward during late Vashon time. Relatively rapid retreat of the Juan de Fuca lobe may have contributed to partial stagnation of the northwestern part of the Puget lobe. Final destruction of the Puget lobe occurred when the ice retreated north of Admiralty Inlet. The sea entered the Puget lowland at this time, allowing the deposition of glacial-marine sediments which now occur as high as 50 m altitude. These deposits, together with ice-marginal meltwater channels presumed to have formed above sea level during deglaciation, suggest that a significant amount of postglacial isostatic and(or) tectonic deformation has occurred in the Puget lowland since deglaciation.

Radiocarbon dates from critical stratigraphic localities in southern British Columbia indicate that the growth history of the late Wisconsin Cordilleran Ice Sheet was different from that of most of the Laurentide Ice Sheet to the east. Much of southern British Columbia remained free of ice until after about 19,000 to 20,000 yr ago; only adjacent to the Coast Mountains is there a record of lowland glacier tongues in the interval 22,000 to 20,000 yr B.P. A major advance to the climax of late Wisconsin Cordilleran glacier ice in the northern States was not begun until after about 18,000 yr B.P. in the southwest of British Columbia and after about 17,500 yr B.P. in the southeast. The rate of glacier growth must have been very rapid in the two to three millennia prior to the climax, which has been dated in western Washington at shortly after 15,000 yr B.P.

The Los Chocoyos Ash, having erupted from vents near the Lake Atitlán caldera, Guatemala, is perhaps the largest Quaternary silicic pyroclastic unit in Central America. It consists of an underlying H-tephra member and an overlying ash-flow member. One-hundred-and-five samples of ash from the Guatemalan Highlands and deep-sea cores in the equatorial Pacific and Gulf of Mexico were analyzed by neutron activation and/or electron microprobe. Glass shard chemistry, determined by microprobe, is useful for distinguishing several very widespread, distinct, deep-sea ash layers, but needs support from trace-element data when applied on land to distinguish between many individual eruptions from the same province. Data from this study support the correlation of the Worzel ‘D’ layer and the Los Chocoyos Ash proposed by Hahn et al. (1979) and Bowles et al. (1973). Chemical data from this study are used to correlate the Y-8 ash layer of the Gulf of Mexico with the Los Chocoyos Ash. The recognition of the Los Chocoyos Ash in the Gulf of Mexico and equatorial Pacific increases the known areal extent of the unit to more than 6 × 106 km2 and allows an age of 84,000 yr B.P. to be assigned to the formation on the basis of oxygen-isotope stratigraphy, biostratigraphy, and Pa-Th-isotope data. Trace-element data obtained from seven other ash layers in the Gulf of Mexico and the equatorial Pacific, when combined with new land-based data, should allow further correlation and dating of ash units in Central America.

Three emergent marine terraces are prominent between Playa El Marron and Arroyo El Salinito and comprise the most extensive Pleistocene planation surfaces in central Baja California, Mexico. The deposits of the lowest terrace, the Tomatal, are 120,000 ± 20,000 yr old (Sangamonian?) while the absolute ages of the two higher and older terraces, the Andrés and Aeropuerto, are unknown. The Tomatal terrace is particularly well developed and comprises degraded sea cliffs, paleodunes, and lagoonal sequences. Shingle paleobeach ridges also occur locally and reflect shore progradation and tombolo formation. The Tomatal shoreline is nearly horizontal at 7 ± 1 m above present mean sea level, whereas the older Aeropuerto terrace has been tilted so that it decreases in elevation toward the southeast. Nonetheless, coastal tilting is not nearly as great as at many other localities in California and Baja California. This is despite the fact that the entire Baja California peninsula has been assumed to be tectonically unstable during the Pleistocene, primarily because of the forces generated by plate motion.

The rates of solifluction of two lobes in the Ruby Range have been determined by 14C dates of samples taken from buried organic layers in the lobes. Twenty-one dates are available from one lobe, and seven from another. When plotted against distance back from control points at the lobe fronts the dates show considerable scatter. In part the scatter is thought to be due to a potential age range of 340 ± 100 yr in the organic layers. Linear and polynomial regressions were calculated for the time/distance relationships shown by the dates. The rates of lobe advance established by these means for the lobe with seven dates are not thought to be reliable. Reasonably good estimates of movement rate were determined for the second lobe by both the linear and polynomial methods. However, the rates established by the two methods are quite similar. Because of this and other uncertainties it is difficult to draw inferences of climatic change from the changes in movement rate shown by the polynomial solution.

Seismic reflection profiles (3.5 kHz) were obtained along more than 3500 km of shiptrack in Lake Superior within the last 2 yr. The acoustic character of profiles is categorized as: (I) a single, strong reflector at the lake floor, (II) a thick, acoustically transparent layer overlying a strong reflector, and (III) relatively thick sediment with internal acoustic reflectors. These profiles, in conjunction with sediment cores from the area, reveal that varved glacial-lacustrine sediment settled out preferentially in a trough between Isle Royale and the north shore, and to a lesser extent in other topographic depressions; bottom currents generated by storm waves prevent clay accumulation on till or bedrock in the open lake wherever the bottom is shallower than 100 m; bottom currents prevent deposition or erode bottom sediment in certain deep-water (> 200 m) valleys; and lacustrine sediment is disturbed by creep or slumping off Grand Portage, Minnesota, and by other processes such as dewatering in many other areas. These factors complicate sedimentation in Lake Superior, and must be considered when investigating any aspect of the lake sediment.

At altitudes below 1300 m most species of grasses in tropical Africa are ones that use 4-carbon photosynthesis. Above 4000 m only species of the subfamily Pooideae using 3-carbon photosynthesis are found. At intermediate altitudes the percent of 3-carbon genera and species in the grass flora is a very regular function of altitude. The correlate of altitude that controls the distribution of grasses appears to be temperature. Fossil grass cuticles are identifiable to genus and should provide a useful paleothermometer. If no other errors were involved, the regular altitudinal distribution of genera in the flora of tropical East Africa would permit paleotemperature estimates with 95% confidence limits of ± 1.2°C.