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In conjunction with detailed geological mapping around the Aim and Straneggtal, in Upper Austria, the landslide deposits have been restudied. Along the southern flank of Meisenberg, coarse angular debris with boulders up to ca. 5m3 size occur. These are composed only of bright Dachsteinkalk sitting as erratic material on the dark-grey limestone of the Gutenstein Formation. The coarse grain size and its distribution only above the trim line of the Last Glacial Maximum (LGM) indicates that this material was deposited in a large-scale rock avalanche. This was derived from the northern rim of the Totes Gebirge and travelled north, spreading out over the glacier and finally reaching the flank of the Meisenberg, some 6km away. Similar deposits at Jh. Miraberg are also remnants of this debris blanket, deposited when the glacier finally malted away. The Hintere Hetzau cirque and the Staneggtal show a conspicuously hummocky topography, covered with huge blocks of Dachsteinkalk. The hummocks consist of densely packed matrix-supported angular debris of Dachsteinkalk and Hauptdolomit, deposited by a huge landslide (ca. 450 million ms. This was derived from the Büchsenkar and formed a sturzstrom filling the whole Straneggtal. The conspicuous ridges north and south of Drackhütte are surge ridges (Fleckberg) and wave-like ridges created by the dynamics of the sturzstrom. On reaching the Almtal, the sturtzstrom probably entered a shallow lake and was transformed into a suspension that was pushed forward by subsequent incoming material. This suspension flow created a terrace body as far north as the Grünau basin. Sedimentary structures indicate that this occurred in a single short event. Lumps of still dry and densely packed landslide material floated in and above the suspension, forming small hills on the surface of the terrace. Larger lumps of still stratified sandy-gravelly river sediments indicate transport in a frozen state indicating wintertime or early spring conditions. 36Cl surface exposure dating indicates that the avalanches occurred at the end of the LGM, probably shortly before the glaciers started their final melting. The boulders at Meisenberg were deposited around 19,000 years ago. The younger main event, at Straneggtal, took place at the end of the Oldest Dryas, after melting of the Gschnitz stadial glaciers; the most representative age of boulder deposition is 15,600 ± 1100 years. [ABSTRACT FROM AUTHOR]

The 100 kyr quasiperiodic variation of continental ice cover, which has been a persistent feature of climate system evolution throughout the most recent 900 kyr of Earth history, has occurred as a consequence of changes in the seasonal insolation regime forced by the influence of gravitational n-body effects in the Solar System on the geometry of Earth's orbit around the Sun. The impacts of the changing surface ice load upon both Earth's shape and gravitational field, as well as upon sea-level history, have come to be measurable using a variety of geological and geophysical techniques. These observations are invertible to obtain useful information on both the internal viscoelastic structure of the solid Earth and on the detailed spatiotemporal characteristics of glaciation history. This review focuses upon the most recent advances that have been achieved in each of these areas, advances that have proven to be central to the construction of the refined model of the global process of glacial isostatic adjustment, denoted ICE-5G (VM2). A significant test of this new global model will be provided by the global measurement of the time dependence of the gravity field of the planet that will be delivered by the GRACE satellite system that is now in space. [ABSTRACT FROM AUTHOR]

How old are most species of North American birds? A longstanding debate centers on whether Pleistocene events caused substantial avian diversification. Two new syntheses of speciation times by Johnson and Cicero, and Weir and Schluter provide compelling evidence of recent Pleistocene speciation, whereas diversification rate analyses by Zink et al. suggest that most speciation events occurred earlier. Although these results are seemingly contradictory, when considered together they provide a robust and complementary perspective on the tempo of avian diversification in North America. [Copyright &y& Elsevier]