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reconstructed from sub-ice shelf and offshore sediments J.A. Smith; C.-D. Hillenbrand; C. Subt; B.E. Rosenheim; T. Frederichs . Abstract: Because ice shelves respond to climatic forcing over a range of time scales, from years to millennia, an understanding of their long-term history is critically needed for predicting their future evolution. We present the first detailed reconstruction of the Larsen C Ice Shelf (LCIS), eastern Antarctic Peninsula (AP), based on data from sediment cores recovered from below and in front of the ice shelf. Sedimentologic and chronologic information reveals that the grounding line (GL) of an expanded AP ice sheet had started its retreat from the midshelf prior to 17.7 ± 0.53 ....
Emilia A. Caylor; Barbara Carrapa; Kurt Sundell; Peter G. DeCelles; Joshua M. Smith Abstract: The Upper Cretaceous Fort Crittenden Formation exposed in the Santa Rita and Huachuca Mountains of southeastern Arizona is a syntectonic deposit that has been associated with Laramide tectonic activity. However, the spatio-temporal relationships among Cretaceous sedimentation, magmatism, basement exhumation, and possible flat slab-related processes in the southern Laramide region remain poorly understood. Age controls for uplift and erosion of local topography and syntectonic deposition in response to deformation remain particularly poor. The Fort Crittenden Formation comprises 800?2500 m of locally derived fluvial to alluvial fan sedimentary rocks and records paleodrainage reorganization in response to active tectonics. Changes in sedimentary facies, provenance, and paleoflow suggest deposition in a tectonically partitioned intraforeland basin. New detrital zircon data constrain the ....
Follow Jan. 6, 2021 Sometimes archaeological evidence may be quite clear, but the story it tells can be mystifying. One such conundrum has been archaeological evidence of relatively intense hilltop farming thousands of years ago in the relatively arid Jerusalem area, the Judean lowlands and northern West Bank. The Iron Age and Byzantine farmers cultivated the chalky, hilly land mostly by terracing. Meanwhile in the abundantly rainy Galilee in Israel’s north, there is no evidence of terracing. The area was just as densely populated but the people seem to have eschewed exploiting the hills, only cultivating crops at low level. It seemed counterintuitive to find the evidence of heavier farming in the drier lands of Jerusalem and Samaria than in the lovely Galilee. ....