Quaternary records of the dire wolf, Canis dirus, in North and South America

The dire wolf was an important large, late Pleistocene predator in North and South America, well adapted to preying on megaherbivores. Geographically widespread, Canis dirus is reported from 136 localities in North America from Alberta, Canada, southward and from three localities in South America (Muaco, Venezuela; Talara, Peru; and Tarija, Bolivia). The species lived in a variety of environments, from forested mountains to open grasslands and plains ranging in elevation from sea level to 2255 m (7400 feet). Canis dirus is assigned to the Rancholabrean land mammal age of North America and the Lujanian land mammal age of South America and was among the many large carnivores and megaherbivores that became extinct in North and South America near the end of the Pleistocene Epoch.     

The Jura glaciers: palaeogeography in the Würmian circum-Alpine zone

Since the first studies on the glacial formations of the Jura mountains there have been two concepts concerning type of glaciation and ice origin during the Würmian glaciation. Some authors believed that the Jura was totally inundated by ice of Alpine origin, while others believed that the Jura had its own glaciers, originating from a single ice-cap. Several recent studies on both the NW and SE slopes of the range define the problem more accurately. This paper presents a synthesis of the new results from mapping the moraine systems and studying the stratigraphic relationships between Alpine and Jura tills. It is concluded that even the highest level of Alpine glaciers could not lead to a penetration of the Jura. A reconstruction of the extension of the Jura glaciers and their relationship with the Alpine glaciers is given, and we conclude that at the Würmian maximum a local ice-cap was present.     

Modern and Holocene hydrographic characteristics of the shallow Kara Sea shelf (Siberia) as reflected by stable isotopes of bivalves and benthic foraminifera

River discharge of Ob and Yenisei to the Kara Sea is highly variable on seasonal and interannual time scales. River water dominates the shallow bottom water near the river mouths, making it warmer and less saline but seasonally and interannually more changeable than bottom water on the deeper shelf. This hydrographic pattern shows up in measurements and modelling, and in stable isotope records (δ¹⁸O, δ¹³C) along the growth axis of bivalve shells and in multiple analyses of single benthic foraminiferal shells. Average isotope ratios increase, but sample-internal variability decreases with water depth and distance from river mouths. However, isotope records of bivalves and foraminifera of a sediment core from a former submarine channel of Yenisei River reveal a different pattern. The retreat of the river mouth from this site due to early Holocene sea level rise led to increasing average isotope values up core, but not to the expected decrease of the in-sample isotope variability. Southward advection of cold saline water along the palaeo-river channel probably obscured the hydrographic variability during the early Holocene. Later, when sediment filled the channel, the hydrographic variability at the core location remained low, because the shallowing proceeded synchronously with the retreat of the river mouth.     

Gould Pond, Maine: late-glacial transitions from marine to upland environments

Gould Pond sediments are unusual in North America in that they include a continuous record of change from marine to freshwater conditions during the late-glacial period, with a wide array of micro- and macrofossils deposited during a period of high sedimentation rate. Marine waters, much colder than those in the present Gulf of Maine, covered the site at the time of deglaciation (c. 13,200 BP). Plants characteristic of modem tundra grew on nearby uplands. Marine recession, due to isostatic rebound of the land, occurred from c . 12,800–12,200 BP. The lake water was completely freshened by 12,000 BP. A sparse shrub-herb tundra became established around Gould Pond as marine waters receded. Subsequent to 11,300 BP, sedges and other herbs became more abundant, and willow and Dryas less abundant, signifying increased warmth and decreased frost action. At least six tree species, all now common in the area, arrived around Gould Pond between c . 10,800 and 10,500 BP. This rapid transition was coincident with the most rapid major non-anthropogenic change of vegetation at sites across eastern North America during the postglacial period.     

Distribution of Late Silurian (?) and Early Devonian grey-green sandstones in the Liefdefjorden-Bockfjorden area, Spitsbergen

Lithologic, petrographic and paleontologic data for the various areas of late Silurian (?) and early Devonian grey-green sandstones (greywackes) in the Liefdefjord area of northern Spitsbergen are evaluated. A number of new localities with fossil fauna have been detected in these sandstones, both to the north and south of Liefdcfjordcn. It is shown that vertebrate and invertebrate fossils occur at lower levels than hitherto believed. Differences in the amounts of plagioclase and potash feldspar in the sandstones north and south of the fjord, as well as the finds of fossils, suggest that the Siktefjellet Sandstone is restricted to the type area north of Liefdefjorden. The grey-green sandstones south of Liefdefjorden are correlated with the Andreebrecn Sandstone Formation of the Red Bay Group.     

EXAMINING LARGE DATABASES:A CHEMOMETRIC APPROACH USING PRINCIPAL COMPONENT ANALYSIS

Principal component analysis is used to examine large multivariate databases.The graphical approachto exploratory data analysis is described and illustrated with a single example of chemical compositiondata obtained on environmental dust particles.While the graphical approach to exploratory data analysishas certain advantages over the numerical procedures,the empirical approach described here should beviewed as complementary to the more robust treatments that statistical methodologies afford.