Late-glacial and Holocene 14C/12C ratios of atmospheric CO2 vary in magnitude from a few per mil for annual/decadal pertubations to more than 10% for events lasting millennia. A data set illuminating 10- to 104-yr variability refines our understanding of oceanic (climatic) versus geomagnetic or solar forcing of atmospheric 14C/12C ratios. Most of the variance in the Holocene atmospheric 14C/12C record can be attributed to the geomagnetic (millennia time scale) and solar (century time scale) influence on the flux of primary cosmic rays entering the atmosphere. Attributing the observed atmospheric 14C/12C changes to climate alone leads to ocean circulation and/or global wind speed changes incompatible with proxy records. Climate-(ocean-)related 14C redistribution between carbon reservoirs, while evidently playing a minor role during the Holocene, may have perturbed atmospheric 14C/12C ratios measurably during the late-glacial Younger Dryas event. First-order corrections to the radiocarbon time scale (12,000–30,000 14C yr B.P.) are calculated from adjusted lake-sediment and tree-ring records and from geomagnetically defined model 14C histories. Paleosunspot numbers (100–9700 cal yr B.P.) are derived from the relationship of model 14C production rates to sunspot observations. The spectral interpretation of the 14C/12C atmospheric record favors higher than average solar activity levels for the next century. Minimal evidence was found for a sun-weather relationship.

A 1-m-deep gully section 460 m beyond the maximum Little Ice Age marginal moraines of Blåisen, Hardangerjøkulen, central southern Norway, revealed alternations of minerogenic and organic sediments. The geographical/geological settings of the dated section provides a unique on/off signal of Holocene glacier fluctuations of Blåisen. Lithostratigraphy, sediment characteristics, and radiocarbon dates from the study section indicate one period of glacier (re)advance between the late Preboreal deglaciation of the inland ice sheet and 8660 ± 100 yr B.P. A grey sand layer 56–57 cm below the surface is interpreted to be of fluvial/colluvial origin and is radiocarbon dated to about 7700 yr B.P. At 48 cm below the surface, a bluish-grey sand/silt layer is radiocarbon dated to 7590 ± 12 yr B.P. (6560–6240 B.C.) and interpreted to be glaciofluvial origin. A minor glacier oscillation postdates 1130 ± 70 yr B.P. (810–990 A.D.). The Medieval/Little Ice Age glacier advance of Blåisen beyond its modern extent occurred after 1040 ± 60 yr B.P. (960–1030 A.D.). Calculations of the modern and Little Ice Age equilibrium-line altitudes (ELAs) on Hardangerjøkulen suggest an ELA depression of ca. 130 m during the Little Ice Age maximum.

A 12-m sequence of lake sediment and peat in a 45-m high exposure on Birch Creek, northeast Alaska, contains pollen of Picea, Betula, Alnus and Populus, and wood of Picea and Populus. This sequence, which may represent 10,000 yr of more of accumulation, is beyond the limit of radiocarbon dating. It lies between two units of loess; the underlying loess lies above the Old Crow Tephra, recently dated at 149,000 ± 13,000 yr B.P. The lake sediments probably were deposited during the last interglaciation (isotope substage 5e) and subsequently buried by Wisconsinan loess. Analogs for the ancient lake may be deep, long-lived thaw lakes that are present in the modern landscape. When Birch Creek is correlated with other sites across nonglaciated Alaska and northwest Canada, there appears to be a common interglacial signal in sediments overlying the Old Crow Tephra.

Twelve reworked shell fragments were recovered from five till samples collected on Nottingham Island in western Hudson Strait, Canada. Total hydrolysate amino acid ratios (D-alloisoleucine/L-isoleucine) for each fragment range from 0.043 to 0.154 and are significantly higher than ratios for radiocarbon-dated Holocene shells, which average 0.022. One shell fragment with an aIle/Ile ratio of 0.065 yielded an AMS radiocarbon age of 44,200 ± 2300 yr B.P. (AA-3254). Absolute age estimates based on the amino acid ratios are constrained by reasonable limits on the estimated effective diagenetic temperature of the fossils. On this basis, the shell fragments are correlated with oxygen isotope substages 5e and 5a and stage 3 in the preferred hypothesis. Theses results independently support hypotheses calling for at least partial deglaciation and marine incursion in Hudson Strait and Hudson Bay at these times.

Amino acid racemization data for marine molluscs of the last interglaciation from southern Australia provide the basis for a predictive model for relative dating of late Quaternary sequences. Genera analyzed include Anadara sp., Katelysia sp., Glycymeris sp., and Fulvia sp. that exhibit moderate racemization rates. A genus effect on racemization is not evident in these taxa. Coefficients of variation for intershell D/L ratio variation for each deposit are generally less than 12%. The extent of racemization in molluscan fossils of the last interglaciation from temperate coastal settings in southern Australia represents an exponential function of temperature and is in general accord with data from Northern Hemisphere sites with similar contemporary mean annual temperature values. These data highlight the potential of amino acid racemization for global correlation programs. The amino acid data from southern Australia suggest, however, that a larger margin of variation may have to be accounted for in stratigraphic correlation, as indicated by the greater scatter of data around the oxygen isotope substage 5e isochron. These data have implications regarding the age-resolving power of amino acid racemization.

Cambridge Fiord functions as a major outlet trough whenever Laurentide ice approaches the eastern coast of Baffin Island. During the last glacial maximum (late Foxe glaciation), an outlet glacier occupied most of the fiord, possibly terminating as far seaward as Buchan Gulf. Glacier retreat began prior to 8800 yr B.P. and was punctuated by the formation of two onshore moraines with upper age limits of 7900 and 7200 yr B.P. Correlative offshore moraines (recognized on seismic reflection profiles) formed prominent submarine sills which partitioned the fiord into three basins. These formed effective sediment traps that restricted the seaward migration of debris flows and turbidites, thus facilitating the accumulation of thick (> 100 m) stratified glacialmarine sediments in the inner fiord. Correlations of onshore and offshore moraines allow time lines to be placed within an offshore seismic stratigraphic section that is inaccessible to piston coring. Resultant estimates of sediment accumulation rates give a mean value of 2.34 × 106 m3/yer for deposits trapped in the inner fiord basins. These thick sequences of sediments do not represent extended Foxe/Wisconsin time periods, but, rather, were rapidly deposited in the inner fiord during the last deglaciation.

Thermoluminescence (TL) age estimates have been obtained on coarse-grained detrital feldspar from Eemian beach sand (substage 5e), early Weichselian dune sands (substages 5d and 5b), and pre-Eemian beach sand. The past radiation dose is obtained using the additive dose method. Even for the oldest samples, which date to 300,000 yr B.P. by other methods, the TL signal is not in saturation and can be doubled by the addition of laboratory radiation doses without saturation being achieved. This is contrasted with the behavior of polymineral, silt-sized grains from loess in the adjacent area. The TL age estimates are systematically underestimated by about 40% when compared with the expected geological ages. However, they are in correct stratigraphic order and demonstrate that stage 5 beach deposits can be distinguished from those resulting from earlier high sea levels using TL signals from potassium feldspars.

Detailed morpho- and lithostratigraphic investigations, allied with radiometric dating, in the Voidomatis basin, Epirus, northwest Greece, have identified four Quaternary terraced alluvial fills that range from middle Pleistocene to historic in age. Major-periods of alluviation during the late Quaternary were associated with valley glaciation (ca. 26,000–20,000 yr B.P.) and subsequent deglaciation (ca. 20,000–15,000 yr B.P.) in the Pindus Mountains during Late Würmian times, and more recently linked to overgrazing sometime before the 11th century AD. The late Quaternary alluvial stratigraphy of the Voidomatis River is more complex than the “Older Fill” and “Younger Fill” model outlined previously, and it is suggested that these terms should no longer form the basis for defining alluvial stratigraphic units in the Mediterranean Basin.

The characteristics of a new type of rock varnish from the hyperarid coastal deserts of northern Peru, combined with laboratory experiments on associated soil materials, provide new insights into the formation of rock varnish. The Peruvian varnish consists of an Fe-rich, Mn-poor component covering up to 95% of a varnished surface and a Fe-rich, Mn-rich component found only in pits and along cracks and ridges. The alkaline soils plus the catalytic Fe oxyhydroxides that coat much of the varnish surfaces make the Peruvian situation ideal for physicochemical precipitation of Mn. However, the low Mn content of the dominant Fe-rich, Mn-poor component suggests that such precipitation is minor. This, plus the presence of abundant bacteria in the Mn-rich varnish and the recorded presence of Mn-precipitating bacteria in varnish elsewhere, suggests that bacteria are almost solely responsible for Mn-precipitation in rock varnish. A set of experiments involving Peruvian soil samples in contact with water-CO2 solutions indicates that natural fogs or dews release Mn but not Fe when they come in contact with eolian materials on rock surfaces. This mechanism may efficiently provide Mn to bacteria on varnishing surfaces. The lack of Fe in solution suggests that a large but unknown proportion of Fe in varnish may be in the form of insoluble Fe oxyhydroxides sorbed onto the clay minerals that form the bulk of rock varnish. The results of this study do not substantively change R. I. Dorn's paleoenvironmental interpretations of varnish Mn:Fe ratios, but they do suggest areas for further inquiry.

January Cave, in the Rocky Mountains of southwestern Alberta, has yielded vertebrate remains from a coprocenosis of mid-Wisconsinan-age. Taphonomic analysis indicates accumulation by raptors, mostly owls, and mammalian carnivores. The vertebrate record, together with pollen analysis, indicates that cool, dry conditions prevailed in an extensive tundra-like environment, with prairie elements in the valleys below. Thirty-four mammalian taxa have been recovered from January Cave. Today, some of these species (e.g., Lemmus sibiricus and Dicrostonyx torquatus) do not coexist with others (e.g., Cynomys sp., Mustela nigripes, Vulpes velox, and Lagurus curtatus). Therefore, the January Cave local fauna represents a “nonanalog” mammalian community characteristic of the late Pleistocene. It suggests that the region enjoyed an equable climate, with reduced climatic extremes but still cool, further supporting a mid-Wisconsinan age estimate for the fauna. It is the first major, small vertebrate fauna of its age to be reported from Alberta.

Distributions of freshwater and brackish-water diatoms from dust samples and modern sediments of the equatorial Atlantic demonstrate different transport mechanisms and source areas. Both Melosira spp. and Stephanodiscus spp. are transported via winds from the southern Sahara and Sahel in Northern Hemisphere winter. The core-top distribution of Cyclotella striata delineates the extent of the low-salinity plume formed by runoff from the Zaire River into the extreme eastern Atlantic. The transport mechanism and source areas for Melosira spp. during arid phases have not changed appreciably in the last 130,000 yr. There is no evidence for long-distance transport of freshwater diatoms by the southeast trade winds. This study confirms the validity of paleoclimatic research which inferred eolian transport of Melosira spp. in the winter dust plume from source regions north of the equator, although fluviatile input of Melosira valves into nearshore sediments cannot be ruled out.