Racetrack Playa in California’s Death Valley is the site of an enduring geological mystery. There are hundreds of stones scattered across the south end of this remote dry lake – and they’re being moved by some force.

Ranging in size from less than half the size of a brick  to blocks big enough to be a footstool, the stones have scoured tracks in the fine clay that are, in some instances, hundreds of metres long.

For more than 90 years, despite the work of multiple researchers, no one has ever seen a move event taking place.

Interwoof partners Jib Ray and Jim Norris  joined with Scripps Institute geologist, Dr Richard  Norris in an effort to solve the mystery.  They called the effort The Slithering Stones Research Initiative and using Interwoof-developed technology they created a set of tiny, robust instrumentation packages to measure any movement.

On 21 December 2013 the  rocks moved, the Interwoof loggers recorded the event in detail and, best of all, both Interwoof’s Jim Norris and Dr. Richard Norris were there when it happened.

The results of their work were published on PLOS | One on 27 August 2014.