Trail formation by ice-shoved "sailing stones" observed at Racetrack Playa, Death Valley National Park
R. D. Lorenz1, J. M. Norris2, B. K. Jackson3, R. D. Norris4, J. W. Chadbourne5, and J. Ray21Applied Physics Laboratory, The Johns Hopkins University, Laurel, Maryland, USA 2Interwoof, Santa Barbara, California, USA 3Dept.~of Terrestrial Magnetism, Carnegie Institution for Science, Washington, D.C., USA 4Scripps Institution of Oceanography, La Jolla, California, USA 5University of Portland, Oregon, USA
Received: 17 Aug 2014 – Accepted for review: 27 Aug 2014 – Discussion started: 28 Aug 2014
Abstract. Trails in the usually-hard mud of Racetrack Playa in Death Valley National Park attest to the seemingly-improbable movement of massive rocks on an exceptionally flat surface. The movement of these rocks, previously described as "sliding stones", "playa scrapers", "sailing stones" etc., has been the subject of speculation for almost a century but is an exceptionally rare phenomenon and until now has not been directly observed. Here we report documentation of multiple rock movement and trail formation events in the winter of 2013–2014 by in situ observation, video, timelapse cameras, a dedicated meteorological station and GPS tracking of instrumented rocks. Movement involved dozens of rocks, forming fresh trails typically of 10s of meters length at speeds of ~5 cm s−1 and were caused by wind stress on a transient thin layer of floating ice. Fracture and local thinning of the ice decouples some rocks from the ice movement, such that only a subset of rocks move in a given event.
Lorenz, R. D., Norris, J. M., Jackson, B. K., Norris, R. D., Chadbourne, J. W., and Ray, J.: Trail formation by ice-shoved "sailing stones" observed at Racetrack Playa, Death Valley National Park, Earth Surf. Dynam. Discuss., 2, 1005-1022, doi:10.5194/esurfd-2-1005-2014, 2014.