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Full-Text Articles in Physical Sciences and Mathematics
River-Bed Armouring As A Granular Segregation Phenomenon, Behrooz Ferdowsi, Carlos P. Ortiz, Morgane Houssais, Douglas J. Jerolmack
River-Bed Armouring As A Granular Segregation Phenomenon, Behrooz Ferdowsi, Carlos P. Ortiz, Morgane Houssais, Douglas J. Jerolmack
Publications and Research
River bed-load transport is a kind of dense granular flow, and such flows are known to segregate grains. While gravel-river beds typically have an “armoured” layer of coarse grains on the surface, which acts to protect finer particles underneath from erosion, the contribution of granular physics to river-bed armouring has not yet been investigated. Here we examine these connections in a laboratory river with bimodal sediment size, by tracking the motion of particles from the surface to deep inside the bed, and find that armour develops by two distinct mechanisms. Bed-load transport in the near-surface layer drives rapid, shear ratedependent …
Raritan Formation (Upper Cretaceous), Long Island, New York: Sedimentological And Geochemical Assessment, Nazrul I. Khandaker, Arif Sikder, Stanley Schleifer, Xin-Chen Liu, Carlos E. Castano Londano, Joseph B. Mcgee Turner
Raritan Formation (Upper Cretaceous), Long Island, New York: Sedimentological And Geochemical Assessment, Nazrul I. Khandaker, Arif Sikder, Stanley Schleifer, Xin-Chen Liu, Carlos E. Castano Londano, Joseph B. Mcgee Turner
Publications and Research
The lithology of the Upper Cretaceous Raritan Formation (RF) consists of two members: an upper clay member (Raritan clay) and a lower unit, the Lloyd Sand Member. RF is unconformably overlain by upper Pleistocene glacial deposits. The RF consists of stratified white, light- to dark-gray, and red beds and lenses of clay, silt, and sand; lignite and pyrite are common. Variegated, thin to thickly-bedded Lloyd sandstone (LS) is considered to be one of the extensive regional aquifers in Long Island and interpreted to be nearshore, fluvio-deltaic deposit. Proximity to fluvial axes and active deltaic lobes plays an important role in …