bluuebunny/crossref_metadata_2025 huggingface dataset:
Chromosomes of the Siberian Snow Sheep, Ovis Nivicola, and Implications Concerning the Origin of Amphiberingian wild Sheep (subgenus Pachyceros)
Authors: Korobitsyna K.V. , Nadler C.F. , Vorontsov N.N. , Hoffmann R.S.
Published: December 2004

The chromosomes of Ovis nivicola, described for the first time, exhibit 2n = 52, the lowest diploid number to be reported for wild sheep and goats. The new chromosomal data, together with a review of the fossil history of the genus, lead us to conclude that the bighorned wild sheep (subgenus Pachyceros) evolved their distinctive characteristics while isolated in the ice-free Beringian refugium, and then migrated southward into western North America when the glacial barriers melted, as first suggested by Cowan (1940).
Pleistocene Vertebrates with Boreal Affinities in the Georgia Piedmont
Authors: Voorhies M.R.
Published: December 2004

Pleistocene alluvium along Little Kettle Creek in east-central Georgia contains a unique record of vertebrate life in the Appalachian Piedmont during a colder phase of the late Quaternary. The small fauna includes fishes and the following mammals: Synaptomys cooperi, the southern bog lemming; Clethrionomys sp., a redback vole; Mammut americanum, the American mastodon; a mammoth, Mammuthus sp.; Odocoileus cf. virginianus, a deer; and Bison sp. Both Synaptomys and Clethrionomys are primarily boreal genera of rodents which today reach their southern limits at higher elevations in the Great Smoky Mountains about 175 km north of the fossil locality. The American mastodon is also commonly associated with Pleistocene spruce bogs in eastern North America. Catfish (Ictalurus (?) sp.) vertebrae from the deposit show well-defined annual rings in contrast with the weakly marked annuli produced by fish living in the same area today. The total aspect of the fauna is one of considerably lower temperatures than those prevailing in the Georgia Piedmont now. The joint occurrence of bison and proboscideans indicates an age no older and no younger than late Pleistocene (Rancholabrean) for the assemblage. Because no pollen was found in the sediments and there was insufficient organic matter present for 14C dating, no more precise age can yet be assigned to the fauna.
Equilibrium-line Altitudes of Late Quaternary Glaciers in the Southern Alps, New Zealand
Authors: Porter Stephen C.
Published: December 2004

Equilibrium-line altitudes (ELA's) of former glaciers in the Tasman River-Lake Pukaki drainage basin of the Southern Alps were reconstructed from glacial-geologic data on former ice limits by using an assumed accumulation-area ratio of 0.6 ± 0.05. Late Holocene (Neoglacial) ELA's were depressed 140 m below present levels, whereas those of four late Pleistocene ice advances were depressed 500 m (Birch Hill), 750 m (Tekapo), 875 m (Mt. John), and 1050 m (Balmoral). Reconstructed ELA gradients are approximately parallel to one another and range from 19 to 23 m km−1. Although vertical movement on active faults and isostatic tilting due to deglaciation have both contributed to modification of reconstructed ELA gradients from their original values, the maximum resulting effect probably amounts to less than 2.0 m km−1 and is undetectable from present data.
The Gothenburg Magnetic Excursion
Authors: Mörner Nils-Axel
Published: December 2004

The Gothenburg Magnetic Excursion in a broad sense ranges from 13,750 to 12,350 years BP and ends with the Gothenburg Magnetic Flip at 12,400−12,350 years BP (= the Fjärås Stadial in southern Scandinavia) with an equatorial VGP position in the central Pacific. The Gothenburg Magnetic Flip is recorded in five closely dated and mutually correlated cores in Sweden. In all five cores, the inclination is completely reversed in the layer representing the Fjärås Stadial dated at 12,400−12,350 years BP. The cores were taken 160 km apart and represent both marine and lacustrine environments. The Gothenburg Magnetic Flip represents the shortest excursion and the most rapid polar change known at present. It is also hitherto the far best-dated paleomagnetic event. The Gothenburg Magnetic Excursion and Flip are proposed as a standard magnetostatigraphic unit.
Observed Formation and Burial of a Recent Human Occupation Site in Kenya
Authors: Gifford Diane P. , Behrensmeyer A. Kay
Published: December 2004

A recent human campsite, occupied in 1973 by members of the Dassanetch tribe of northern Kenya, was observed from its creation through its subsequent burial in flood events 4 months later. The site was excavated as an archeological occurrence in the summer of 1974. Analyses of field and laboratory data yield a detailed picture of sedimentary structures, bone transport and burial, and site preservation in a well-documented depositional situation. Trampling by site occupants was apparently instrumental in burying much small bone prior to the flood events which acted on the site. About 30 cm of sediments accumulated on the site during four or five flood events. Individual sedimentary beds can be related to specific observed flood events in the drainage system. The ultimate preservation of the site as part of the region's archeological record would depend upon the interaction of sediment deflation and the varying local water table. Specific conditions which tend to preserve human sites in water-poor environments may consistently select seasonally biased vestiges of human settlement and economy.
Grande Pile Peat Bog: A Continuous Pollen Record for the Last 140,000 Years
Authors: Woillard Geneviève M.
Published: December 2004

In the Southern Vosges Mountains, Northeastern France, the Grande Pile peat bog (47° 44′ N, 6°30′14″ E, 330-m altitude, about 20 m deep) gives a continuous pollen sequence for the last 140,000 years, contrary to others in Northwestern and Central Europe which are all truncated. For the first time, in a region close to the type locatity for the Eem deposits and close to the Würm and Riss stratotypes, palynology demonstrates a complete “glacial-interglacial cycle” offering the possibility of studying the rapid degradation of vegetation at the end of the Last Interglacial, perhaps in sufficient detail to be useful soon in long-term global climate forecasting. The Grande Pile pollen sequence shows, between the classical Eemian Interglacial and the Last (Würm) Glaciation, two temperate intervals interpreted as interglacials (palynological definition): St. Germain I and St. Germain II. These are separated by two very cold phases, probably glacial: Melisey I and Melisey II. This sequence, not easily correlated with the classical European chronology of Woldstedt, agrees well with Frenzel's chronology and, therefore, makes the synchrony of the Alpine glaciations with those of Northern Germany questionable. An attempt is made to correlate the Grande Pile pollen sequence with other chronologies (e.g., deep sea curves based on foraminiferal fauna, oxygen isotopes, and carbonate content, Barbados sea levels, Rocky Mountains sequence) that span the period between 140,000 and 70,000 years BP.
Quaternary Studies in Corsica (France)
Authors: Conchon Odette
Published: December 2004

Fluvial, glacial, and colluvial deposits in Corsica have been studied in terms of their distribution, soils, sedimentology (arrangement, shape analysis, size analysis, petrography, and weathering of pebbles; size distribution, shape analysis, and mineralogy of matrix), and relationships to marine sediments. A relative chronology is based on the topographic and stratigraphic relationships between the sediments, and to a large extent on their degree of weathering. The intensity and the type of pebble weathering suggest a possible correlation of the older alluvial units with the Alpine Quaternary succession. Quaternary paleoclimates in Corsica alternated between glacial and interglacial. During glacial stages, when glaciers developed in the high mountains and formed tongues in the valleys, periglacial climates characterized the low altitude zone. Tectonic movements occurred in Corsica during the Quaternary, probably until the Middle Würm.
Late Pleistocene Paleoclimates of North America as Inferred from Stable Isotope Studies of Speleothems
Authors: Harmon Russell S. , Thompson Peter , Schwarcz Henry P. , Ford Derek C.
Published: December 2004

Some speleothems (CaCO3cave deposits) can be demonstrated to have been formed in oxygen isotopic equilibrium with their parent seepage waters and thus a record of relative fluctuations in depositional temperature can be obtained from the δ18O variations in successive growth layers of such deposits. These temperature fluctuations reflect variations in the average annual air temperature at the surface above the cave, and therefore permit inference of past continental climate changes. Equilibrium deposits have been obtained from caves in San Luis Potosi, Bermuda, Kentucky, West Virginia, Iowa, and Alberta, ranging in age from 200,000 years BP to the present, as determined by230Th/234U dating of the speleothems. The δ18O time curves for the six sites show the following synchronous climatic fluctuations: warm periods from 190 to 165 and from 120 to 100 Ka, at 60 and 10 Ka, and cold periods from 95 to 65 and from 55 to 20 Ka. The periods of thermal maxima correspond in time to the interglacial periods of the marine foraminiferal isotopic and faunal temperature records and to periods of high sea stand as observed from radiometric dating of raised coral reefs. Maxima and minima in insolation appear to be synchronous with this record as well.
Reevaluation of Multiparameter Relative Dating Techniques and their Application to the Glacial Sequence Along the Eastern Escarpment of the Sierra Nevada, California
Authors: Burke R. M. , Birkeland Peter W.
Published: December 2004

Four valleys, recently studied by other workers, were examined along the eastern Sierra Nevada to refine relative-dating techniques. A variety of weathering parameters and soil properties fail to delineate more than two major post-Sherwin Pleistocene glaciations. We correlate these two glaciations with the Tahoe and Tioga Glaciations. Type Mono Basin Till, usually considered to be pre-Tahoe, exhibits the following weathering similarities with Tahoe Till, if both are under sagebrush: (1) grusification of subsurface granitic boulders; (2) degree of pitting, mineral relief, and rind development on surface granitic boulders; and (3) very slight clay increase in the B horizon. Type Casa Diablo Till also has weathering characteristics similar to Tahoe Till, except a slightly more developed Bt horizon is present. Hence, dates on basalt of 0.126 ± 0.025 and 0.062 ± 0.013 my Casa Diablo Till also has weathering characteristics similar to Tahoe Till, except a slightly more developed Bt horizon is present. Hence, dates on basalt of 0.126 ± 0.025 and 0.062 ± 0.013 my (Bailey et al. 1976), which bracket type Casa Diablo, may provide age control on the Tahoe glaciation. In addition, we are unable to demonstrate that the Tenaya is a separate glaciation. In three of the four valleys studied our weathering data for Tenaya Till are equivalent with those for Tioga Till, but with those for Tahoe Till in the fourth valley. We were not satisfied with our ability to differentiate the Casa Diablo, Mono Basin, and Tenaya as separate glaciations even though data were collected in the type areas for two of these deposits. Reasons for suggesting a change back to a two-fold Tahoe-Tioga glacial sequence, rather than the present five-fold sequence, are that we have measured a greater number of parameters than has been done previously, soils were submitted to detailed laboratory analyses, and surface weathering features were studied under consistent present vegetation cover to avoid possible problems induced by ancient forest fires. Nevertheless our relative-dating scheme does not rule out the possibility of a more detailed glacial sequence.
Obsidian Hydration Dating of Volcanic Events
Authors: Friedman Irving , Obradovich John
Published: December 2004

Obsidian hydration dating of volcanic events had been compared with ages of the same events determined by the 14C and K — Ar methods at several localities. The localities, ranging in age from 1200 to over 1 million yr, include Newberry Craters, Oregon; Coso Hot Springs, California; Salton Sea, California; Yellowstone National Park, Wyoming; and Mineral Range, Utah. In most cases the agreement is quite good. A number of factors including volcanic glass composition and exposuretemperature history must be known in order to relate hydration thickness to age. The effect of composition can be determined from chemical analysis or the refractive index of the glass. Exposure-temperature history requires a number of considerations enumerated in this paper.
Plankton Ecology and the Paleoceanographic–Climatic Record
Authors: Loubere Paul
Published: December 2004

The paleoceanographic–climatic record represented by deep-sea microfossils reflects conditions for only certain times of the year. Also, the relative abundances of microfossil species in deep-sea sediments do not usually reflect only one paleoceanographic variable, such as temperature. Rather, species distributions represent the integration of many factors that control biological production in the oceans. This influences the information on past climates that can be extracted from fossil material. The seasonal limitation is due to the cyclic nature of biological production in the open ocean. Case studies of the sediment record in the Atlantic for two species of planktonic Foraminifera, left-coiling Neogloboquadrina pachyderma (Ehrenberg) and Globigerinoides ruber (d'Orbigny), illustrate seasonal bias in environmental data reported by the relative abundances of species in deep-sea sediments. In addition, the study of G. ruber illustrates the operation of two oceanographic parameters in controlling a species distribution. These examples demonstrate that the environmental signal in the sediments is the result of the interplay of the ecological tolerance of the plankton species with seasonally variable biological and physical properties of the upper ocean.
Amino Acid Geochemistry of Fossil Bones from the Rancho La Brea Asphalt Deposit, California
Authors: McMenamin Mark A. S. , Blunt David J. , Kvenvolden Keith A. , Miller Scott E. , Marcus Leslie F. , Pardi Richard R.
Published: December 2004

Low aspartic acid d:l ratios and modern collagenlike concentration values indicate that amino acids in bones from the Rancho La Brea asphalt deposit, Los Angeles, California are better preserved than amino acids in bones of equivalent age that have not been preserved in asphalt. Amino acids were recovered from 10 Rancho La Brea bone samples which range in age from less than 200 to greater than 36,000 yr. The calibrated rates of aspartic acid racemization range from 2.1 to 5.0 × 10−6yr−1. Although this wide range of rate constants decreases the level of confidence for age estimates, use of the larger rate constant of 5.0 × 10−6yr−1provides minimum age estimates which fit the known stratigraphic and chronologic records of the Rancho La Brea deposits.
Chronologic and Environmental Implications of a New Genus of Fossil Deer from Late Wisconsin Deposits at Toronto, Canada
Authors: Churcher C. S. , Peterson R. L.
Published: December 2004

A new cervine deer (Torontoceros hypogaeus), described from a partial cranium with portions of the main antler beams, has been recovered from deposits of early Lake Ontario age on the exposed bench of Glacial Lake Iroquois at Toronto, Ontario, Canada. The deer was about the size of a caribou, has heavy antlers that lie chiefly in a nearly horizontal plane, and its beams are bowed anteriorly. The tines are not flattened, the brow tines are asymmetrical, and no evidence of surface roughening or palmation of the beam is found. A 14C date of 11,315 ± 325 yr B.P. obtained on the antler allows the date at which Glacial Lake Iroquois drained to be revised to before 11,400 yr B.P. Spruce (Picea), pine (Pinus), and sedges (Cyperaceae) are major components of the associated pollen spectrum, which implies a typically interstadial or postglacial climate in which mixed forests grew in the Toronto area.
Carbon Isotopic Changes in Benthic Foraminifera from the Western South Atlantic: Reconstruction of Glacial Abyssal Circulation Patterns
Authors: Curry W. B. , Lohmann G. P.
Published: December 2004

Oxygen- and carbon-isotopic analyses have been performed on the benthic foraminifer Planulina wuellerstorfi in seven Late Quaternary cores from the Vema Channel-Rio Grande Rise region. The cores are distributed over the water-depth interval of 2340 to 3939 m, which includes the present transition from North Atlantic Deep Water (NADW) to Antarctic Bottom Water (AABW).

The carbon-isotopic records in the cores vary as a function of water depth. The shallowest and deepest cores show no significant glacial-interglacial difference in δ13C. Four of the five cores presently located in the NADW have benthic foraminiferal δ13C that is lower during glacial isotopic stages. Based on bathymetric gradients in δ13C, we conclude that, like today, there were two water masses present in the Vema Channel during glacial intervals: a water mass enriched in 13C overlying another water mass depleted in 13C. The largest gradient of change of δ13C with depth, however, occurred at 2.7 km, ∼ 1 km shallower than the present position of this gradient.

On the basis of paleontologic and sedimentologic evidence, we consider it unlikely that the NADW:AABW transition shallowed to this level. Reduced carbon-isotopic gradients between the deep basins of the North Atlantic and Pacific Oceans during the last glaciation suggest that production of NADW was reduced. Lower production of NADW may have modified the local abyssal circulation pattern in the Vema Channel region.
Pseudo-Ice-Wedge Casts of Connecticut, Northeastern United States
Authors: Black Robert F.
Published: December 2004

Since 1965, ice-wedge casts have been reported in deposits of sand and gravel in Connecticut. These are wedge forms up to 1.1 m wide and many meters high. Most are single forms, not in polygonal array. They are found in adjoining states as well. Their distribution, dimensions, structure, and fabric and an assessment of the former physical environment preclude their origin as permafrost features. They appear to be tension fractures produced by the loading of coarse clastics on fine clastics near and below the water table where sediments creep toward a stream or depression. Locally movement started with kettle formation during deglaciation. However, some wedges cut horizontal layers of iron-coated sand and gravel and must be younger than those distinctly postglacial phenomena. Moreover, modern B horizons of the overlying soil have moved down into some wedges more than 2 m, indicating that fracturing is still active today. Complex fracture fillings in bedrock also have been attributed to a permafrost origin, but this too seems unlikely.
The Age of Glacier Peak Tephra in West-Central Montana
Authors: Mehringer Peter J. , Sheppard John C. , Foit Franklin F.
Published: December 2004

At Sheep Mountain Bog, near Missoula, Montana, a late-glacial tephra, that probably fell in late summer, is preserved as an 8-mm-thick graded bed overlain by another 8 mm of redeposited ash mixed with lake deposits. Sediment surrounding the ash was 14C dated to about 11,200 yr B.P. Electron-microprobe analyses of the volcanic glass and hornblende phenocrysts from this ash layer indicate that they are similar in major-element chemistry to those of Glacier Peak layer G previously considered to be about 12,000 yr old or older.
Distribution of an Arctic Ostracod Fauna in Space and Time
Authors: Delorme L.D. , Zoltai S.C.
Published: December 2004

A fossil locality on the Pembina Upland, in southern Manitoba (L. D. Delorme, Geological Association of Canada, Special Paper9, 301–304, 1971), contains three ostracod species near the base of the deposit. Two of these ostracods, Candona rectangulata and Cyclocypris globosa, are found alive only in the northern parts of the Northwest and Yukon territories of Canada. Both species are indicative of subarctic forest tundra and alpine tundra. Their position in the lower 69 cm of the deposit indicates that, as the glacier ice thinned over the upland and retreated from the Lake Agassiz basin, an arctic-subarctic environment could have existed with the potential for tundra vegetation to develop. A reverse situation occurred in the Northwest Territories based on seven fossil ostracod species from a peaty marl deposit. As reported by L. D. Delorme, S. C. Zoltai, and L. L. Kalas. (Canadian Journal of Earth Science14, 2029–2046, 1977) for other similar sites, the striking element is the absence of true arctic ostracods. The majority of the species live very successfully further south in Manitoba and Saskatchewan at present. At both sites, the fossil assemblage is different than the modern assemblage. This indicates a dislocation in space and time which is the basis for the change in paleoenvironmental interpretation.
New Data on the Stratigraphy and Pedology of the Clovis and Plainview Sites, Southern High Plains
Authors: Holliday Vance T.
Published: December 2004

The well known Clovis and Plainview archaeological sites of New Mexico and Texas have yielded new data on regional late Quaternary geologic, paleoclimatic, and pedologic histories. Eolian sedimentation at the Clovis site from about 10,000 to less than 8500 yr B.P. was followed by the formation of a cumulic soil between 8500 and 5000 yr B.P. Episodic eolian and slope wash deposition then culminated in massive eolian sedimentation about 5000 yr B.P. after which a Haplustalf formed then was subsequently buried by part of a dune system within the last 1000 yr. At the Plainview site, a basal stream gravel contains Plainview cultural material (ca. 10,000 yr B.P.), which is followed by a localized early Holocene lacustrine deposit, two eolian deposits (the younger dating to about 5000 yr B.P.), and a marsh deposit which slowly accreted as an Argiustoll formed in the younger eolian unit. The data indicate that on the Southern High Plains (1) between 12,000 and 8500 yr B.P. sedimentation varied from site to site, (2) there was a regional climate change toward warming and drying in the early Holocene, (3) two episodes of severe drought apparently occurred in the middle Holocene (6500 to 4500 yr B.P.), (4) between 4500 yr B.P. and the present an essentially modern climate existed, but with several shifts toward aridity within the last 1000 yr, (5) argillic horizons have developed in late Holocene soils, (6) clay illuviation can occur in calcareous soils, and (7) long-distance correlation of Holocene stratigraphy in the region is possible, particularly with the aid of soil morphology.
Late Holocene Paleoecology and Sedimentary History of a Small Lowland Catchment in Central England
Authors: Brown Antony G. , Barber Keith E.
Published: December 2004

A variety of paleoecological and sedimentary techniques were used to investigate the storage of sediment within a small lowland catchment during the Holocene. Radiocarbon dating of vertically accreted floodplain deposits allowed the calculation of inorganic accumulation rates. These rates show a dramatic increase in sediment deposition during the late Bronze Age and early Iron Age (2900-2300 yr B.P.) due to deforestation and cultivation of the catchment slopes and resultant soil erosion. The soils within the catchment were susceptible to structural damage, surface waterlogging, and slope-wash erosion. From the calculated increases in sediment storage estimates of catchment erosion were made which vary from around 20 to 140 tons km−2 yr−1. The study of alluvial chronology at this scale can provide unique information on the source areas of Holocene floodplain sediments and provide long-term erosion rates.
Paleomagnetic Data Bearing on the Age of High Terrace Deposits (Durance Sequence) in Alpine Valleys of Southeastern France
Authors: Dubar Michel , Semah François
Published: December 2004

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.
Extinct Mountain Goat (Oreamnos harringtoni) in Southeastern Utah
Authors: Mead Jim I. , Agenbroad Larry D. , Phillips Arthur M. , Middleton Larry T.
Published: December 2004

The extinct Harrington's mountain goat (Oreamnos harringtoni Stock) is predominantly known from dry cave localities in the Grand Canyon, Arizona, in addition to two sites in the Great Basin, Nevada, and from San Josecito Cave, Nuevo Leon, Mexico. A dry shelter in Natural Bridges National Monument, on the central Colorado Plateau, southeastern Utah, preserves numerous remains of the extinct mountain goat in addition to pack rat middens. Remains from a 100-cm stratigraphic profile indicate that O. harringtoni lived on the plateau >39,800 yr B.P., the oldest directly dated find of extinct mountain goat. Plant macrofossils indicate that Engelmann's spruce (Picea engelmannii), limber pine (Pinus flexilis), rose (Rosa cf. woodsii), and Douglas fir (Pseudotsuga menziesii) grew during the late Pleistocene where a riparian and a pinyon-juniper (Pinus edulis-Juniperus osteosperma) community now predominates; Douglas fir are found only in mesic, protected, north-facing areas. Limber pine, Douglas fir, bark, and grasses were the major dietary components in the dung. A springtime diet of birch (Betula) is determined from pollen clumps in dung pellets.
The Anomalous Roxana Silt and Mid-Wisconsinan Events in and Near Southern Michigan
Authors: Winters Harold A. , Alford John J. , Rieck Richard L.
Published: December 2004

Thick deposits of Roxana Silt are recognized only along the Illinois River (downstream from the Woodfordian terminal moraine) and are generally interpreted as being mainly loess, with the bulk accumulating from about 40,000 to 30,000 yr ago in association with an Altonian-age glacier in northeastern Illinois. Yet 11 14C dates indicate that southern Michigan was not ice-covered during that interval; thus, any proximate ice must have, at best, been restricted to Great Lakes basins, an interpretation supported by the absence of late Altonian till at critically located Michigan, and nearby, sites. Late mid-Wisconsinan ice did, however, obstruct eastern drainage of the ancestral Great Lakes. Such glacial blockage, the distribution of many Michigan organic deposits within pre-Woodfordian lacustrine sediments, and radiocarbon dates suggest that, more than once, late Altonian lakes associated with the Lake Michigan basin drained into the Illinois River. Erosion of lake and spillway bluffs along with repeated river fluctuations provided a source for the thick, geographically restricted Roxana Silt. Meanwhile, along other nearby rivers the supply was meager and the loess thin.
Source and Origin of Roxana Silt and Middle Wisconsinan Midcontinent Glacial Activity
Authors: Johnson W. Hilton , Follmer Leon R.
Published: December 2004

Thick Roxana Silt (middle Wisconsinan) in central and southwestern Illinois traditionally has been interpreted as loess derived from valley-train deposits in the ancient Mississippi River valley. Winters et al. (H. A. Winters, J. J. Alford, and R. L. Rieck, Quaternary Research 29, 25–35, 1988) recently suggested that the Roxana was not directly related to glacial activity, but was derived from sediment produced by increased shoreline and spillway erosion associated with a fluctuating ancestral Lake Michigan. Because (1) paleoenvironmental and paleohydrologic conditions inferred in the hypothesis are unlikely for a loess depositional system and (2) loess did not accumulate during late Wisconsinan deglaciation under conditions similar to those hypothesized, we suggest the hypothesis should be rejected. Roxana distribution suggests the major source was drainage from the upper Mississippi River valley, and variations in loess thickness in Illinois can be explained by consideration of valley width, depth, orientation, and postdepositional erosion. Tills in the headwaters region of the ancient Mississippi drainage system in Minnesota and Wisconsin occur in the appropriate stratigraphic position and have colors and mineralogic compositions that suggest they could be the parent till of the Roxana. We believe a valley-train source for thick Roxana is most probable and urge continued consideration of middle Wisconsinan glaciation in the upper Great Lakes area.
Pre-Wisconsinan Mammals from Jamaica and Models of Late Quaternary Extinction in the Greater Antilles
Authors: MacPhee R. D. E. , Ford Derek C. , McFarlane Donald A.
Published: December 2004

The vertebrate fauna recovered from indurated conglomerates at Wallingford Roadside Cave (central Jamaica) is shown to be in excess of 100,000 yr old according to uranium series and electron spin resonance dating. The Wallingford local fauna is therefore pre-Wisconsinan in age, and Roadside Cave is now the oldest radiometrically dated locality in the West Indies containing identifiable species of land mammals. In the absence of a good radiometric record for Quaternary paleontological sites in the Caribbean, there is no satisfactory basis for determining whether most extinct Antillean mammals died out in a “blitzkrieg”-like event immediately following initial human colonization in the mid-Holocene. Fossils of Clidomys (Heptaxodontidae, Caviomorpha), the giant Wallingford rodent, have never been found in situ in sediments of demonstrably Holocene age, and its extinction may antedate the middle Holocene. This is also a possibility for the primate Xenothrix mcgregori, although its remains have been found in loose cave earth. A major, climate-driven bout of terrestrial vertebrate extinction at about 14,000–12,000 yr B.P. has been hypothesized for the West Indies by G. Pregill and S. L. Olson (Annual Review of Ecology and Systematics 12, 75–98, 1981), but at present there is nothing to connect the disappearance of Clidomys with this event either. Quaternary extinctions in the Caribbean may prove to be of critical significance for evaluating the reality of New World blitzkrieg, but not until an effort is mounted to constrain them rigorously using modern radiometric approaches.
Climatic Change at the End of the Last Glaciation in Japan Inferred from Pollen in Three Cores from the Northwest Pacific Ocean
Authors: Heusser Linda E. , Morley Joseph J.
Published: December 2004

Late-glacial pollen time-series from high-sedimentation-rate marine cores KH79-3-C6, CH84-04, and CH84-14 show the rise of successional vegetation (typified by Betula) during the replacement of boreal forest types (Picea and Pinus) by thermophilous Quercus forests. Variations in these three marine pollen records replicate the trends and timing of pollen records from Japan and the structure and timing of vegetation and climatic changes on the Pacific coast of Japan since the last glacial maximum. In marine cores KH79-3-C6, CH84-04, and CH84-14, oxygen isotope and/or marine faunal data have been interpreted as evidence of a cooling event in the northwest Pacific Ocean which is coeval with the Younger Dryas chronozone. Pollen records from these northwest Pacific cores, like those from Japan, do not exhibit a regionally replicated, statistically robust, pollen assemblage which can be unambiguously interpreted as evidence of a late-glacial climatic reversal between ca. 11,000 and 10,000 yr B.P. The apparent disparity between the terrestrial (pollen) and marine evidence for a climatic oscillation during the Younger Dryas chron in northeast Asia further complicates the variable record of this brief late-glacial event.
Displacement of Salt by the Laurentide Ice Sheet
Authors: White William A.
Published: December 2004

In central New York, deformation of salt of the Salina Formation by the Laurentide Ice Sheet is shown by a thinning of the salt stratum in and near the outcrop zone where it was overridden by the ice sheet and by a thickening down-dip near the glacial limit. Less definitive suggestions of deformation by glacial overriding of the Salina outcrop zone in northeastern Ohio are seen in salt-cored anticlines in the vicinity of the glacial limit. In the lower peninsula of Michigan, isopachs of salt curve around Saginaw Bay, which suggests that the salt was displaced southwestward, away from the bay, by pressure of the Saginaw lobe of the ice sheet. All but one of the major Paleozoic salt deposits of North America lie in a zone that girdles two-thirds of the Canadian Shield from where glacial erosion removed all but occasional outliers of Phanerozoic strata.
Quaternary Coastal Evolution and Vegetation History of Northern New South Wales, Australia, Based on Dinoflagellates and Pollen
Authors: McMinn Andrew
Published: December 2004

The Richmond River Valley of northern N.S.W. contains a late Pleistocene succession dating back to approximately 250,000 yr B.P. Dinoflagellate and spore-pollen assemblages from the lowest interval, the lower “Dungarubba Clay” of Drury (1982), indicate deposition in a restricted estuarine environment at approximately 250,000 yr. Deposition in the overlying interval, the upper “Dungarubba Clay” and “Gundurimba Clay”, at approximately 120,000 yr B.P., began in a restricted estuary, but rising sea level caused inundation and deposition in a more open, marine-dominated environment. Dinoflagellate cyst assemblages from the last interglaciation (stage 5) are interpreted by analogy with those from the morphologically similar, modern Broken Bay, N.S.W. They are indicative of an open, marine-dominated environment and imply that barrier formation in the Richmond River Valley, and possibly elsewhere in northern N.S.W., did not commence until after the initial postglacial transgression. Synchronous changes in sea level and rainforest development suggest that there was no significant time lag between climate and sea-level change.
Progress, but not a full solution to the logical problem of language acquisition
Authors: HOFF ERIKA
Published: December 2004

MacWhinney argues that the logical problem of language acquisition is no longer. It was a problem back in the 1970s when the guiding premises of the field were that language structure is highly abstract, that the child's input is a poor source of information about grammar, and that the child's learning mechanisms are inadequate to bridge the gap between the input the child receives and the grammar the child acquires. Now, however, we have new linguistic theories which show that language structure is not abstract but arises from cognition, and we have evidence that input is a rich source of information, and we have reason to believe that the child has a powerful array of learning procedures at his or her disposal. The gap between input and acquisition thought to exist in the 1970s has been closed, and thus, MacWhinney argues, there is no need to attribute innate linguistic knowledge to the child.
False belief understanding in Cantonese-speaking children
Authors: TARDIF TWILA , WELLMAN HENRY M. , MAN CHEUNG KAR
Published: December 2004

The present study investigates the performance of 96 Cantonese-speaking three- to five-year-old preschoolers on three false belief tasks – a deceptive object, a change of location, and an unexpected contents task encompassing a variety of task factors. Most importantly, the research examines the possibility that false belief performance depends on specific linguistic factors such as the type of verb used in the test question – an explicitly false vs. a neutral belief verb. Cantonese was chosen as particularly useful for examining this question because it explicitly codes belief status as either neutral (nam5) or false (ji5wai4), and because it offers additional linguistic and cultural contrasts to research conducted on false belief with children learning English and other Indo-European languages. As expected, a strong age effect was found, as well as a significant advantage for children who received the explicit false belief (ji5wai4) wording and for those who were asked to explain rather than predict the protagonist's actions. Interestingly, there was also a strong task difference with children performing better on the deceptive object task than on the other two false belief tasks. We argue that these results point both to universal trajectories in theory of mind development and to interesting, but localized, effects of language and culture on children's false belief understanding.
Observations of O2:CO2 exchange ratios during ecosystem gas exchange
Authors: Seibt U. , Brand W. A. , Heimann M. , Lloyd J. , Severinghaus J. P. , Wingate L.
Published: December 2004

We determined O2:CO2 exchange ratios of ecosystem fluxes during field campaigns in different forest ecosystems (Harvard Forest/United States, Griffin Forest/United Kingdom, Hainich/Germany). The exchange ratios of net assimilation observed in chamber experiments varied between 0.7 and 1.6, with averages of 1.1 to 1.2. A measurement of soil gas exchange yielded an exchange ratio of 0.94. On the other hand, the observed canopy air O2:CO2 ratios, derived from the concurrent variations of O2 and CO2 abundances in canopy air, were virtually indistinguishable from 1.0 over the full diurnal cycle. Simulations with a simple one‐box model imply that the combined processes of assimilation, respiration, and turbulent exchange yield canopy air O2:CO2 ratios that differ from the exchange ratios of the separate fluxes. In particular, the simulated canopy air O2:CO2 ratios (1.01 to 1.12) were clearly lower than the exchange ratios of net turbulent fluxes between the ecosystem and the atmosphere (1.26 to 1.38). The simulated canopy air ratios were also sensitive to changes in the regional O2:CO2 ratio of air above the canopy. Offsets between the various exchange ratios could thus arise if the component ecosystem fluxes have different diurnal cycles and distinct exchange ratios. Our results indicate that measurements of O2 and CO2 abundances in canopy air may not be the appropriate method to determine O2:CO2 exchange ratios of net ecosystem fluxes.
An empirical analysis of the spatial variability of atmospheric CO2: Implications for inverse analyses and space‐borne sensors
Authors: Lin J. C. , Gerbig C. , Daube B. C. , Wofsy S. C. , Andrews A. E. , Vay S. A. , Anderson B. E.
Published: December 2004

We provide quantitative estimates for the spatial variability of CO2, crucial for assessing representativeness of observations. Spatial variability determines the mismatch between point observations and spatial averages simulated by models or observed from space‐borne sensors. Such “representation errors” must be properly specified in determining the leverage of observations to retrieve surface fluxes or to validate space‐borne sensors. We empirically derive the spatial variability and representation errors for tropospheric CO2 over the North American continent and the Pacific Ocean, using in‐situ observations from extensive aircraft missions. The spatial variability and representation error of CO2 is smaller over the Pacific than the continent, particularly in the lowest altitudes, and decreases with altitude. Representation errors resulting from spatial variability in the summer continental PBL are as large as 1∼2 ppmv for typical grid resolutions used in current models for inverse analyses.
Characterization of Asian dust and Siberian smoke with multi‐wavelength Raman lidar over Tokyo, Japan in spring 2003
Authors: Murayama Toshiyuki , Müller Detlef , Wada Katsuya , Shimizu Atsushi , Sekiguchi Miho , Tsukamoto Tatsuro
Published: December 2004

In the spring of 2003, we observed lofted Asian dust and Siberian forest‐fire smoke plumes in the free troposphere over Tokyo, Japan with a dual‐wavelength Raman lidar. These data show clear signatures of the optical characteristics depending on the aerosol type. The Asian‐dust layer shows that the particle depolarization ratio (PDR) at 532 nm is ∼20%, and the extinction‐to‐backscatter ratio (lidar ratio) at 355 nm is ∼49 sr, which is close to ∼43 sr measured at 532 nm. On the contrary, the smoke layers show that the PDR is as small as 5–8% or less, and the lidar ratio at 355 nm is ∼40 sr, which is considerably lower than ∼65 sr which was measured at 532 nm. We also applied an inversion algorithm for the smoke case. The effective radius was ∼0.22 μm and the single‐scattering albedo at 532 nm was ∼0.95.
Evidence for hygroscopic mineral dust particles from the Intercontinental Transport and Chemical Transformation Experiment
Authors: Perry Kevin D. , Cliff Steven S. , Jimenez‐Cruz Michael P.
Published: December 2004

Two collocated, eight‐stage rotating drum impactors were deployed at Trinidad Head (California) during the spring of 2002 as part of the Intercontinental Transport and Chemical Transformation 2002 (ITCT 2K2) experiment. One of the samplers operated at ambient relative humidity while the other was operated at a relative humidity of 55%. The impaction substrates from these samplers were analyzed using synchrotron X‐ray fluorescence (SXRF) to provide continuous measurements of the size‐resolved aerosol elemental composition with 3‐hour time resolution. The aerosol elemental composition data identified three significant mineral dust episodes near the beginning of the time series. The backward air mass trajectory calculations from the Hybrid Single‐Particle Lagrangian Integrated Trajectory (HYSPLIT) model and the PM10 to PM2.5 elemental mass ratios are consistent with the long‐range transport of mineral dust from Asian sources. The data from the paired ambient relative humidity and low‐relative‐humidity samplers show that the aluminum, silicon, and iron elemental mass distributions are a function of relative humidity. In each case, the elemental mass distributions shifted toward smaller sizes as the relative humidity was reduced. This behavior indicates that the mineral dust transported from Asia to the west coast of the United States is somewhat hygroscopic upon its arrival. The hygroscopic nature of the aged mineral dust should increase its ability to nucleate cloud droplets (i.e., act as cloud condensation nuclei). Measurements of transported Asian mineral dust made at a high‐elevation mountain site in Oregon (i.e., Crater Lake National Park) during the spring of 2002 show a strong correlation between the silicon and sulfur elemental mass concentrations. The ratio of calcium to sulfur makes it unlikely that this coarse sulfur is derived from gypsum (i.e., CaSO4). Instead, it indicates that the coarse mineral dust most likely accumulates sulfate coatings either near the source region or during transport across the Pacific Ocean.
Effect of convection on the summertime extratropical lower stratosphere
Authors: Dessler A. E. , Sherwood S. C.
Published: December 2004

Satellite and in situ water vapor and ozone observations near the base of the overworld (θ ≈ 380‐K potential temperature) are examined in summertime northern midlatitudes, with a focus on how their horizontal variations are influenced by deep convection. We show that summertime convection has a significant effect on the water vapor budget here, but only a small effect on the ozone budget. Using a simple model, we estimate that convection increases model extratropical water vapor at 380 K by 40% but decreases model extratropical ozone by only a few percent, relative to what would occur without convection. In situ data show that this convective injection occurs up to at least ∼390 K. This raises the possibility that the convectively moistened air might travel isentropically to the tropics and ascend into the stratospheric overworld without passing through the cold point. We argue that trends in convective moistening should be examined as possible contributors to observed trends in lower stratospheric water vapor, at least during summer months.
Penetration through a slot in a conducting plane backed by a conducting‐wall channel: Transverse electric case
Authors: Lockard M. D. , Butler C. M.
Published: December 2004

The penetration of the electromagnetic field through an infinite slot in a conducting plane backed by a conducting‐wall channel is examined. The total transverse‐electric‐to‐slot‐axis field in the interior of the channel and above the conducting plane is determined by two independent integral equation methods: (1) a coupled integral equation method which can be used to determine the field in the case of a channel with an arbitrarily shaped cross section and (2) a single integral equation method which involves a Green's function specific to the shape of the backing channel. Data from the two methods are presented for the equivalent currents obtained from the integral equations, for the field near the channel‐backed slot, and for the actual currents present on the conducting surfaces.
Survival of protozoan intracellular parasites in host cells
Authors: Leirião Patrícia , Rodrigues Cristina D , Albuquerque Sónia S , Mota Maria M
Published: December 2004

The most common human diseases are caused by pathogens. Several of these microorganisms have developed efficient ways in which to exploit host molecules, along with molecular pathways to ensure their survival, differentiation and replication in host cells. Although the contribution of the host cell to the development of many intracellular pathogens (particularly viruses and bacteria) has been unequivocally established, the study of host‐cell requirements during the life cycle of protozoan parasites is still in its infancy. In this review, we aim to provide some insight into the manipulation of the host cell by parasites through discussing the hurdles that are faced by the latter during infection.
Golden mean renormalization for a generalized Harper equation: The Ketoja–Satija orchid
Authors: Mestel B. D. , Osbaldestin A. H.
Published: December 2004

We provide a rigorous analysis of the fluctuations of localized eigenstates in a generalized Harper equation with golden mean flux and with next-nearest-neighbor interactions. For next-nearest-neighbor interaction above a critical threshold, these self-similar fluctuations are characterized by orbits of a renormalization operator on a universal strange attractor, whose projection was dubbed the “orchid” by Ketoja and Satija [Phys. Rev. Lett. 75, 2762 (1995)]. We show that the attractor is given essentially by an embedding of a subshift of finite type, and give a description of its periodic orbits.
On a classification of irreducible almost commutative geometries
Authors: Iochum Bruno , Schücker Thomas , Stephan Christoph
Published: December 2004

We classify all irreducible, almost commutative geometries whose spectral action is dynamically nondegenerate. Heavy use is made of Krajewski’s diagrammatic language. The motivation for our definition of dynamical nondegeneracy stems from particle physics where the fermion masses are nondegenerate.
Quantum confinement effect of silicon nanocrystals in situ grown in silicon nitride films
Authors: Kim Tae-Youb , Park Nae-Man , Kim Kyung-Hyun , Sung Gun Yong , Ok Young-Woo , Seong Tae-Yeon , Choi Cheol-Jong
Published: December 2004

Silicon nanocrystals were in situ grown in a silicon nitride film by plasma-enhanced chemical vapor deposition. The size and structure of silicon nanocrystals were confirmed by high-resolution transmission electron microscopy. Depending on the size, the photoluminescence of silicon nanocrystals can be tuned from the near infrared (1.38eV) to the ultraviolet (3.02eV). The fitted photoluminescence peak energy as E(eV)=1.16+11.8∕d2 is evidence for the quantum confinement effect in silicon nanocrystals. The results demonstrate that the band gap of silicon nanocrystals embedded in silicon nitride matrix was more effectively controlled for a wide range of luminescent wavelengths.