 EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes
and phenomena which shape our planet and our lives. EPOD will collect and
archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


 EPOD 20th - The Mysterious Moving Rocks

   September 20, 2020

    MYSTERIOUSMOVINGROCKS
   We’re celebrating 20 years of Earth Science Picture of the Day during
   the month of September! Today’s photo features a popular EPOD from the
   past. Thanks to all of our followers (on the blog, Facebook, Instagram
   and Twitter) for supporting us. Thanks also to all of you who’ve
   submitted your photos. We’re most appreciative. This EPOD was
   originally published March 5, 2002.

   Provided by:  Joe Orman
   Summary author:  Joe Orman

   In a remote corner of California's Death Valley National Park, on the
   floor of a dry lakebed called Racetrack Playa, can be seen the
   geological oddity of the sliding stones. While the force of gravity
   easily explains how dozens of rocks -- weighing up to 700 pounds --
   could have fallen from the adjacent hillsides onto the margins of this
   long-vanished ancient lake, it cannot explain how the rocks have moved
   far out onto the perfectly flat surface.

   No one has ever seen the rocks actually move, but the evidence is
   indisputable: distinct tracks in the hard clay surface, some extending
   for hundreds of feet. Some of the grooves are arrow-straight, while
   others curve, take sharp turns, or even make complete loops.

   For decades scientists have plotted the tracks, analyzed the soil, and
   charted the weather in an attempt to solve the mystery. All of the
   theories involve extremely strong winds, but they differ on the exact
   physical process that allows the rocks to overcome friction. Is the
   answer mud, water, ice -- or some combination of these? What is clear
   is that the Racetrack is a unique opportunity for science to explain
   what at first appearance seems to be completely inexplicable.

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   Earth Science Picture of the Day is a service of the  Universities
   Space Research Association.

https://epod.usra.edu
 
