Une roche vagabonde dans la Vallee de la Mort
Image Credit:
Keith Burke
How did this big rock end up on this strange terrain?
One of the more unusual places here on
Earth
occurs inside
Death
Valley,
California,
USA.
There a dried lakebed named
Racetrack Playa exists that is almost perfectly flat,
with the odd exception of some very large stones, one of which is
pictured here in April of 2019 beneath a dark,
Milky-Way filled sky.
Now the
flatness and texture of large playa like
Racetrack
are fascinating but not
scientifically puzzling -- they are caused by mud
flowing, drying, and cracking after a heavy rain.
Only recently, however, has a
viable scientific hypothesis been given to explain how heavy
sailing stones
end up near the middle of such a large flat surface.
Unfortunately, as frequently happens in science,
a seemingly surreal
problem ends up having a
relatively mundane solution.
It turns out that in winter thin floating ice sheets form
in a rare ephemeral lake, and light winds
push ice sections that then push
even heavy rocks across the temporarily flooded
playa when sunlight begins to melt the ice.