Abstract

Flow rolls found in Chemung rocks are elongate nodules of fine-grained sandstone, with an undersurface that is convex downward. They occur either isolated or in layers and clusters, but are consistently found resting in shale or mudstone displaying laminae partially encircling the nodules. Among external markings of the flow rolls are transverse grooves, considered the result of sculpting by flowing mud. X-ray radiographs show laminae distorted to form internal structures ranging from simple basins to complex folds. It is postulated that some nodules originated by foundering of lenticular sand bodies into underlying mud, or some, from load deformation of layers of sand overlying mud. Seismic vibrations may have been an important factor in inducing foundering of sand and resultant flowage of thixotropic mud, which were the main agents in molding the nodules. Similar flowage is also present in cores of the diapiric anticlines closely associated with the flow rolls at one locality.

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