DURHAM, N.C. – A paper by A. Brad Murray, associate professor of geomorphology and coastal processes at the Nicholas School of the Environment and Earth Sciences at 91, has been selected as one of the top 20 most cited papers published in the journal Continental Shelf Research between 2003-2007.

The paper, “A New Hypothesis and Exploratory Model for the Formulation of Large-scale Inner-shelf Sediment Sorting and ‘Rippled Scour Depressions,’” was published in the journal in 2004.

Murray’s co-author was E.R. Thieler, of the U.S. Geological Survey, Coastal and Marine Geology Program, at Woods Hole.

Murray and Thieler ’s paper focused on the formation of sorted bedforms (sometimes called rippled scour depressions), which are collections of relatively coarse sediment that can extend for kilometers out into the ocean. Scientists previously believed the depressions were associated with cross-shore sediment transport. But Murray and Thieler hypothesized that the collections of coarse sediment were, instead, the result of along-shore sediment transport.

They proposed that wave motions interacting with large wave-generated ripples in the coarse sediment generate near-bed turbulence that enhances the entrainment of coarse materials while inhibiting the settling of fine material. Unable to settle to the ocean floor, the fine sediment is carried away by currents and deposited in areas where the ocean bed is composed of finer materials. These interactions, Murray and Thieler hypothesized, tend to produce accumulations of fine material separated by self-perpetuating patches of coarse sediment. They tested their hypothesis using a numerical model and found that large-scale sorted patterns of sediment exhibiting the main characteristics of the natural features resulted “robustly” in the model, indicating that their new hypothesis offered a plausible explanation for the phenomena.

Continental Shelf Research is a leading scientific journal that publishes peer-reviewed articles dealing with the physical oceanography, sedimentology, geology, chemistry, biology and ecology of the shallow marine environment, from coastal and estuarine water out to the shelf break.

Murray has been an associate professor in the Nicholas School’s Division of Earth and Ocean Sciences since 2005, and was an assistant professor from 1998 to 2005. Prior to joining the Nicholas School faculty, he was a postdoctoral associate at the Scripps Institution of Oceanography’s Institute of Geophysics and Planetary Physics, and at the University of Minnesota.

He is the author or co-author of more than 40 peer-reviewed papers and nearly 90 published abstracts and conference proceedings.