An estimate of the sliding velocity and basal meltwater discharge of the Puget lobe of the Cordilleran ice sheet can be calculated from its reconstructed extent, altitude, and mass balance. Lobe dimensions and surface altitudes are inferred from ice limits and flow-direction indicators. Net annual mass balance and total ablation are calculated from relations empirically derived from modern maritime glaciers. An equilibrium-line altitude between 1200 and 1250 m is calculated for the maximum glacial advance (ca. 15,000 yr B.P.) during the Vashon Stade of the Fraser Glaciation. This estimate is in accord with geologic data and is insensitive to plausible variability in the parameters used in the reconstruction. Resultant sliding velocities are as much as 650 m/a at the equilibrium line, decreasing both up- and downglacier. Such velocities for an ice sheet of this size are consistent with nonsurging behavior. Average meltwater discharge increases monotonically downglacier to 3000 m3/sec at the terminus and is of a comparable magnitude to ice discharge over much of the glacier's ablation area. Paleoclimatic inferences derived from this reconstruction are consistent with previous, independently derived studies of late Pleistocene temperature and precipitation in the Pacific Northwest.

A new quantitative, reproducible method for determining relative ages of unconsolidated Quaternary deposits containing granitic clasts has been developed and tested. The technique makes use of a microseismic timer to determine the compressional wave velocity (clast-sound velocity) in each clast of a group chosen from a single deposit. From these data a group mean velocity is determined that is proportional to the age of the deposit: the youngest deposits having the highest velocities. The clast-sound velocity method was used to study Quaternary deposits in the San Gabriel Valley and San Gabriel Mountains, California, using a previously proposed four-part age classification for the deposits. The clast-sound velocity group means for the four age groups were found to be statistically separable at better than 99% confidence. A velocity/age correlation curve was determined for these deposits using two radiocarbon dates and one paleomagnetic determination. This curve suggests that the clast-sound velocity method may be used to determine ages of deposits up to one million years old when calibrated with sufficient radiometric dates and may also be used as a tool for correlating undated deposits.

Stream channels in the Paria River basin were eroded and partially refilled between 1883 and 1980. Basin-wide erosion began in 1883; channels were fully entrenched and widened by 1890. This erosion occurred during the well-documented period of arroyo cutting in the Southwest. Photographs of the Paria River channel taken between 1918 and 1940 show that the channel did not have a floodplain and remained wide and deep until the early 1940s. A thin bar (<50 cm), now reworked and locally preserved, was deposited at that time. Basin-wide aggradation, which began in the early 1940s, developed floodplains by vertical accretion. The floodplain alluvium, 1.3–3 m thick. consists of two units recognizable throughout the studied area. An older unit was deposited during a time of low flow and sediment yield whereas the younger unit was deposited during times of high flow, sediment yield, and precipitation. Tree-ring dating suggests that the older unit was deposited between the early 1940s and 1956, and the younger between 1956 and 1980. The units are not time transgressive, suggesting that deposition by knickpoint recession was not an important process. High peak-flood discharges were associated with crosion and low flood discharges with aggradation. The erosional or aggradational mode of the streams was determined principally by peak-flood discharge, which in turn was controlled by precipitation.

During recent humid episodes, stromatolites were built along paleolake margins, some 60 m above the modern water level of Lakes Natron and Magadi (southern Gregory Rift Valley). Three generations of stromatolites are observed, the more recent ones frequently covering pebbles and boulders eroded from the older ones. The youngest one yielded 14C ages ranging from approximately 12,000 to 10,000 yr B.P. Their δ13C values (≥2.6%) suggest isotopic equilibrium between the paleolake total inorganic dissolved carbon and the atmospheric CO2, thereby lending credence to the reliability of the 14C. An initial 230Th/232Th ratio in the detrital component was determined by Th/U measurements on the 14C dated stromatolites. Using this value a 230Th/234U chronology for the older stromatolites was calculated. Ages of ≥240,000 and 135,000 ± 10,000 yr were obtained for the first and second generations, respectively. A humid episode apparently characterized eastern Africa during each glacial-interglacial transition. 18O and 13C measurements on stromatolites, when compared to values on modern waters and carbonates, provide paleohydrological information. Long residence time of the paleolake waters and less seasonally contrasted regimes are inferred.

Human occupation and utilization of plant resources have affected vegetation in the lower Little Tennessee River Valley of East Tennessee for 10,000 yr. Changes in Indian cultures and land use are documented by radiocarbon chronologies, lithic artifacts, ceramics, settlement patterns, and ethnobotanical remains from 25 stratified archaeological sites within the Holocene alluvial terrace. The ethnobotanical record consists of 31,500 fragments (13.7 kg) of wood charcoal identified to species and 7.7 kg of carbonized fruits, seeds, nutshells, and cultigens from 956 features. Pollen and plant macrofossils from small ponds both in the uplands and on lower stream terraces record local vegetational changes through the last 1500 to 3000 yr. Human impact increased after cultigens, including squash and gourd, were introduced ca. 4000 yr B.P. during the Archaic cultural period. Forest clearance and cultivation disturbed vegetation on both the floodplain and lower terraces after 2800 yr B.P., during the Woodland period. Permanent Indian settlements and maize and bean agriculture extended to higher terraces 1.5 km from the floodplain by the Mississippian period (1000 to 300 yr B.P.). After 300 yr B.P., extensive land clearance and cultivation by Historic Overhill Cherokee and Euro-Americans spread into the uplands beyond the river valley.

Field surveys of several sea-level indicators (exposed in situ reef framework, conglomerates, coral colonies and Tridacna shells in a growth position, sea-corrosion notches) carried out on six atolls from the NW Tuamotus (Mataiva, Rangiroa, Arutua, Kaukura, Apataki and Takapoto) and data from four subsurface boreholes drilled through Mataiva show that during the late Holocene mean sea level (MSL) reached a maximum elevation at approximately + 0.9 m. It remained above the present MSL from between 6000 and 5500 yr B.P. until at least 1200 yr B.P. Human settlements on the atolls were extremely unlikely and probably impossible throughout this time. The area investigated seems to have been tectonically quite stable during the late Holocene. A local curve of MSL variations may be representative of the regional eustatic pattern.

A comparison of uranium-series geochronology and radiocarbon dating, the first systematic test of its kind applied to authigenic marine apatite, has been made for nine seafloor phosphate nodules sampled from the Peruvian and Chilean shelves. Radiocarbon ages agree well with the 230Th ages for all six samples with 230Th ages younger than the practical dating limit of the 14C technique for marine samples. Two of three “old” samples contain no significant 14C activities, as expected. However, one sample with a high concentration of phosphate pellets contains more than 30% of the modern 14C activity. The discrepancy between the 14C and U-series age for this sample is thought to be due to post-depositional adsorption of the particle-reactive elements thorium and protactinium onto pellet surfaces.

A new multidisciplinary research program, started in 1981, provided new data on the stratigraphy, fauna, and human industries, as well as the first results on paleomagnetism and sedimentology, for the Ternifine site in Algeria, which yielded the earliest hominid remains known in North Africa. The fossils were deposited in a swamp or lake surrounded by a very open, dry environment. The lake was fed by artesian springs that raised the underlying Miocene sands. Although nothing suggests a camp or butchery site, we discovered the first undisputable bone artifact in this site, the earliest known in this part of Africa. According to paleontological data, 700,000 yr B.P. is a likely age for the Ternifine deposits, which is consistent with the paleomagnetic results.

In the Durance valley, high terrace levels are stepped below the young. Villafranchian surface and separated from the middle and low terraces by a step 80 m high. A paleomagnetic study was made of a key bed of freshwater silt on the high terrace, that contains archaic faunal and floral elements. The section contains two sedimentary cycles with opposite polarities, which are therefore placed on either side of the Brunhes-Matuyama boundary. By comparison with the northern European climato-stratigraphy, this sequence is correlated with the base of the Cromerian complex. Taking into account the morphological relations to the upland morainic system, this youngest high terrace is assigned a Günz age.

A chronological sequence of plant macrofossil assemblages from twenty-five pack rat middens provides a record of desert scrub vegetation for most of the last 13,380 yr B.P. from a hyperarid portion of the lower Colorado River Valley. At the end of the late Wisconsin, and probably during much of the Quaternary, the Picacho Peak area, Imperial County, California, supported a typical Mohave Desert association of Larrea divaricata (creosote bush), Coleogyne ramosissima (blackbrush), Yucca brevifolia (Joshua tree), and Y. whipplei (Whipple yucca). Recent arrivals of Sonoran Desert plants such as Olneya tesota (ironwood) and Fouquieria splendens (ocotillo) suggest that the area supported relatively modern Sonoran desert scrub species for relatively short periods during interglaciations.