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Articles 1 - 4 of 4
Full-Text Articles in Physical Sciences and Mathematics
Early Eocene Biotic And Climatic Change In Interior Western North America, Scott L. Wing, Thomas M. Bown, John D. Obradovich
Early Eocene Biotic And Climatic Change In Interior Western North America, Scott L. Wing, Thomas M. Bown, John D. Obradovich
United States Geological Survey: Staff Publications
Imprecise correlation of the marine and terrestrial fossil records has been a major obstacle to understanding migration and extinction of continental biotas and early Cenozoic climate change
U And Sr Isotopes In Ground Water And Calcite, Yucca Mountain, Nevada: Evidence Against Upwelling Water, J. S. Stuckless, Z. E. Peterman, Daniel R. Muhs
U And Sr Isotopes In Ground Water And Calcite, Yucca Mountain, Nevada: Evidence Against Upwelling Water, J. S. Stuckless, Z. E. Peterman, Daniel R. Muhs
United States Geological Survey: Staff Publications
Hydrogenic calcite and opaline silica deposits in fault zones at Yucca Mountain, Nevada, have created considerable public and scientific controversy because of the possible development of a high-level nuclear waste repository at this location. Strontium and uranium isotopic compositions of hydrogenic materials were used to test whether the veins could have formed by upwelling of deep-seated waters. The vein deposits are isotopically distinct from ground water in the two aquifers that underlie Yucca Mountain, indicating that the calcite could not have precipitated from ground water. The data are consistent with a surficial origin for the hydrogenic deposits.
Additional Fossil Evidence On The Differentiation Of The Earliest Euprimates, Kenneth D. Rose, Thomas M. Bown
Additional Fossil Evidence On The Differentiation Of The Earliest Euprimates, Kenneth D. Rose, Thomas M. Bown
United States Geological Survey: Staff Publications
Several well-preserved jaws of the rare North American omomyid primate Steinius vespertinus, including the first known antemolar dentitions, have been discovered in 1989 and 1990 in the early Eocene Willwood Formation of the Bighorn Basin, Wyoming. They indicate that its dental formula is as primitive as those in early Eocene Donrussellia (Adapidae) and Teilhardina (Omomyidae) - widely considered to be the most primitive known euprimates - and that in various dental characters Steinius is as primitive or more so than Teilhardina. Therefore, despite its occurrence at least 2 million years later than Teilhardina, S. vespertinus is the …
The Pangaean Megamonsoon- Evidence From The Upper Triassic Chinle Formation, Colorado Plateau, Russell F. Dubiel, Judith Totman Parrish, J. Michael Parrish, Steven C. Good
The Pangaean Megamonsoon- Evidence From The Upper Triassic Chinle Formation, Colorado Plateau, Russell F. Dubiel, Judith Totman Parrish, J. Michael Parrish, Steven C. Good
United States Geological Survey: Staff Publications
The Upper Triassic Chinle Formation was deposited at an exceptional time in Earth's paleogeographic and paleoclimatic history. During the Triassic, the supercontinent Pangaea was at its greatest size, in terms of both aggregated continental crust and exposed land area. Moreover, the exposed land was divided symmetrically about the paleoequator between the northern and south- ern hemispheres. These conditions were ideal for maximizing monsoonal circulation, as predicted from paleoclimate models. The Chinle was deposited between about 5° to 15° N paleolatitude in the western equatorial region of Pangaea, a key area for documenting the effects of the monsoonal climate. This study …