“The massive forms jostle and grate, ions collide, and the sound of thunder is heard above the sun-drenched land. More clouds emerge from the empty sky, and anvil-headed giants with glints of lightening in their depths.”
~ Desert Solitaire by Edward Abbey,1968

With the chance of rain last week, together with an article I read in August, the above quotation was fitting for Weather in the Foothills.

Fall weather has finally arrived. Temperatures have dropped by 20 degrees. A few leaves are turning color with some hanging brown as a result of the drought. Due to the extended dry period and an absence of precipitation, more of the southwest has become desert-like. The driest location in North America also holds the record for having the hottest atmospheric temperature on Earth. On July 10, 1913, Death Valley, California reached 134 degrees!

Last year in Death Valley an observation and discovery were made, solving an age-old mystery. Years before, native Shoshone, and subsequent people, noticed long inscribed trails, seemingly made by rocks, along the smooth floor of Death Valley. Explanations of their origins ranged from spiritual to extraterrestrial, and included good scientific ones, also.  This geological phenomenon is referred to as “sailing stones,” “sliding rocks” and “moving rocks.” The area was named Racetrack Playa (racetrack because of the side-by-side trails and playa, meaning dry lake bed). Wonder of wonders, the mystery is weather-created!

Using time-lapse photography and GPS, paleobiologist Dr. Richard D. Norris of the Scripps Institution of Oceanography documented the movements of 60 rocks. Having also witnessed the rocks moving, he said, “It was complete dumb luck.”

In addition to “luck,” research revealed rainwater runoff from surrounding mountains collects and freezes on the valley floor. Upon partial thawing, light breezes and wind-driven water push the sheets of ice against the rocks. The rocks creep along, leaving trails behind. Come warm dry weather, the markings are revealed. In August 2014 in a research article, Norris shared his findings, calling them “a brief moment in time.” Mystery solved.

The NWS is calling the summer weather pattern officially “gone.” Saturday, Tuesday and Monday bring remnants of weak cold fronts. No rain, but cooler temperatures are predicted.

Hopefully rain is coming.

Sue Kilpatrick is a
Crescenta Valley resident and
Official Skywarn Spotter for the
National Weather Service. Reach her at  suelkilpatrick@gmail.com.