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Full-Text Articles in Physical Sciences and Mathematics

High-Resolution Study Of Layering Within The Percolation And Soaked Facies Of The Greenland Ice Sheet, Joel Brown, Joel T. Harper, W. Tad Pfeffer, Neil Humphrey, John H. Bradford Dec 2011

High-Resolution Study Of Layering Within The Percolation And Soaked Facies Of The Greenland Ice Sheet, Joel Brown, Joel T. Harper, W. Tad Pfeffer, Neil Humphrey, John H. Bradford

Geosciences Faculty Publications

Within the percolation and soaked facies of the Greenland ice sheet, the relationship between radar-derived internal reflection horizons and the layered structure of the firm column is unclear. We conducted two small-scale ground-penetrating radar (GPR) surveys in conjunction with 10 m firm cores that we colleced within the percolation and soaked facies of the Greenland ice sheet. The two surveys were separated by the distance of about 50 km and about 340 m of elevation leading to about 40 days of difference in the duration of average annual melt. At the higher site (about 1997 ma.s.l.), which receives less melt, …


The Impact Of Local Source Sediments On Bed Texture In The Fall River, Rocky Mountain National Park, Usa, Jordan A. Clayton, Kristopher N. Eby Oct 2011

The Impact Of Local Source Sediments On Bed Texture In The Fall River, Rocky Mountain National Park, Usa, Jordan A. Clayton, Kristopher N. Eby

Geosciences Faculty Publications

The bed texture of a gravel-bed river is related to the size distribution and quantity of source sediments, the routing of sediment through the reach, and the distribution of flow velocity. A reach morphology that is consistent in depth with little lateral topographic variation will typically have a bed texture that is characterized by a fairly uniform grain size distribution. However, spatial variations in source sediments within a given watershed may impact the distribution of gravel-bed river sediments, even at the reach scale, such that two proximal reaches of the same river having the same general morphology can exhibit contrasting …


Hydraulics, Morphology, And Energy Dissipation In An Alpine Step-Pool Channel, Andrew C. Wilcox, Ellen E. Wohl, Francesco Comiti, Luca Mao Jan 2011

Hydraulics, Morphology, And Energy Dissipation In An Alpine Step-Pool Channel, Andrew C. Wilcox, Ellen E. Wohl, Francesco Comiti, Luca Mao

Geosciences Faculty Publications

To investigate the relationship between hydraulics and channel morphology in step‐pool channels, we combined three‐dimensional velocity measurements with an acoustic Doppler velocimeter and topographic surveys in a steep step‐pool channel, the Rio Cordon, Italy. Measurements were organized around step, pool, and tread units and occurred within a range of 36%–57% of bankfull discharges. As flow moved from steps to their downstream pools in our study reach, an average of approximately two thirds of the total energy was dissipated, as measured by relative head loss through step‐pool sequences. Much of this head loss was achieved by elevation (potential energy) loss rather …


Lithology And Internal Structure Of The San Andreas Fault At Depth Based On Characterization Of Phase 3 Whole-Rock Core In The San Andreas Fault Observatory At Depth (Safod) Borehole, Kelly Keighley Bradbury, James P. Evans, J. S. Chester, F. M. Chester, D. L. Kirshner Jan 2011

Lithology And Internal Structure Of The San Andreas Fault At Depth Based On Characterization Of Phase 3 Whole-Rock Core In The San Andreas Fault Observatory At Depth (Safod) Borehole, Kelly Keighley Bradbury, James P. Evans, J. S. Chester, F. M. Chester, D. L. Kirshner

Geosciences Faculty Publications

We characterize the lithology and structure of the spot core obtained in 2007 during Phase 3 drilling of the San Andreas Fault Observatory at Depth (SAFOD) in order to determine the composition, structure, and deformation processes of the fault zone at 3 km depth where creep and microseismicity occur. A total of approximately 41 m of spot core was taken from three separate sections of the borehole; the core samples consist of fractured arkosic sandstones and shale west of the SAF zone (Pacific Plate) and sheared fine-grained sedimentary rocks, ultrafine black fault-related rocks, and phyllosilicate-rich fault gouge within the fault …