Paleogene landscape evolution of the central North American Cordillera: Developing topography and hydrology in the Laramide foreland
Steven J. Davis et al., Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA. Pages 100-116.
From the chemical signature of lake and river waters preserved in rocks between roughly 50 and 40 million years ago, Davis et al. have reconstructed the hydrologic environment of basins formed during uplift of the modern Rocky Mountains. Further, they show that the varied environments in the basins (e.g. freshwater lakes, saline lakes, and river systems) are largely the result of changes in the sources and amounts of water flowing to the basins. Finally, they suggest that there may have been a large-scale pattern to the hydrologic changes that occurredmoving gradually from north to south, and mirroring the pattern of volcanism going on at nearly the same time to the west in what is now Idaho and Nevada.
Neogene sediment structures in Bounty Trough, eastern New Zealand: Influence of magmatic and oceanic current activity
G. Uenzelmann-Neben et al., Alfred-Wegener-Institute fur Polar- und Meeresforschung, Postfach 120161, 27515 Bremerhaven, Germany. Pages 134-149.
New seismic reflection profiles have been interpreted by Uenzelmann-Neben et al. to shed more light on the Neogene deposition in Bounty Trough, an aborted rift characterizing the eastern New Zealand continental margin. Two major processes influencing the deposition were identified. Magmatic activity led to the formation of basement highs, which deform the sedimentary sequences up to early and middle Miocene. The origin of the magmatism unfortunately cannot be solved with the new data presented by Uenzelmann-Neben et al. It is diffi
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Geological Society of America