Sliding stones of Racetrack Playa, Death Valley, USA: The roles of rock thermal conductivity and fluctuating water levels

Sliding Bones: Movement of Skeletal Material Over Smith Creek Playa in Nevada and Its Taphonomic and Paleontologic Implications

“…In the second manner, an object is encased by ice floating on liquid water. This was demonstrated by Lorenz et al (2011) in a laboratory experiment, observed for one rock on Racetrack Playa , and concluded from a field study of Racetrack Playa (Kletetschka et al 2013). The third mechanism involves pooled liquid water in which microbial mats buoy up objects and provide additional reduction of surface friction with the playa (Sanz-Montero and Rodríguez-Aranda 2013).…”

“…Given the presence of conditions required for movement involving ice and the lack of evidence for microbial mats, this material probably moved by one or both of the previously summarized means involving wind-blown sheet ice floating on liquid water (e.g., Lorenz et al 2011, Kletetschka et al 2013. Whether these bones moved in an encasement of ice (Lorenz et al 2011, Kletetschka et al 2013 or were free of it as they were being "bulldozed" ) cannot be determined from the evidence available.…”

“…Causes of movement have been speculated about in the literature since at least the late 1940s (MacAllister and Agnew 1948). Recently favored explanations involve various combinations of water, wind, low temperature, and microbial mats (e.g., Messina and Stoffer 2000, Lorenz et al 2011, Kletetschka et al 2013, Sanz-Montero and Rodríguez-Aranda 2013). All of these need water and wind.…”

A Miniscule System of a ‘Sailing Rock’

“…Furthermore it was postulated that ice rafts form around the blocks [10], reducing the specific weight of the entire system, and providing buoyancy lifting the rocks off the lake bed, acting as 'rafts' rather than as 'sailors' , which were then driven by the winds over the plane surface [19,20]. This model was further developed by Kletetschka et al in a laboratory experiment [21].…”

“…The water needed for this system to work comes from the Racetrack mountain area, which drains into the Race Track Playa, building an ephemeral pond during winter times [21]. New GPS-and time-lapse analyses in 2014, however, finally disposed of this former 'ice raft theory' .…”