Podrobnosti záznamu

Název
    Sliding stones of Racetrack Playa, Death Valley, USA: The roles of rock thermal conductivity and fluctuating water levels
Autor
    Fercana, G.
    Hooke, R. L.
    Kletetschka, Günther
    McKinney, E.
    Ryan, A.
    Schwebler, K. P.
Jazyk
    anglicky
Typ dokumentu
    článek v odborném periodiku
Zdrojový dokument - seriál
    Geomorphology
Svazek/č.
    Roč. 195, 1 August
Strany
    s. 110-117
Rok
    2013
Poznámky
    Rozsah: 8 s. : E
Předmětová kategorie
    Endorheic
    Finite element modeling
    hydrogeology
    Racetrack playa
    sliding stones
Klíčové slovo
    Conductivity
    Death
    Fluctuating
    Levels
    Playa
    Racetrack
    Rock
    Roles
    Sliding
    Stones
    Thermal
    USA
    Valley
    Water
Abstrakt (anglicky)
   On occasion, Racetrack playa in Death Valley National Park becomes flooded and temperatures then drop appreciably below freezing. The thermal conductivity of rock is greater than that of water, so heat is conducted from a partially-submerged rock faster than from water. Consequently, a collar of thicker ice forms at the water surface, a layer of ice forms on more deeply-submerged parts of the rock, and playa sediment beneath the rock may even become frozen to it. While this occurs, only a surface layer of ice forms on water away from the rock. Once the ice becomes thick enough, perhaps only 5-10. mm, either the buoyancy of the ice or additions of water to the playa by rain, snow-melt, or groundwater seepage then reduce the normal force between the rock and the playa to the point where wind shear can move the ice sheet with its entrained rocks, making trails (Stanley, 1955; Reid et al., 1995).
   After the ice melts, rocks are left at the ends of the trails, sometimes atop a pedestal of silt. A renewed increase in water level on the playa before the ice melts may lift a rock completely free of the playa surface and whisk it away, leaving a rockless trail. During a movement event, changes in rock orientation or water depth may result in changes in width along the track. Rock speeds are likely tens to hundreds of millimeters per second.
Přispěvatel
    AV ČR Brno, Geologický ústav
Kód přispěvatele
    AV ČR, GLÚ
Zdrojový formát
    U
Datum importu
    23. 10. 2014