Playa
Along 375
This is a roadside Earthcache but for everyone's safety, please use the nearby pulloff. Thank you.
Everywhere there are deserts, you'll find dry lake beds. They're the best setting in the world for certain activities: Launching rockets. Landing the Space Shuttle. Doing secretive military tests (low flying aircraft) and breaking land speed records.
What creates these remarkable features? To create a dry lake bed you need a desert. In the driest places, permanent rivers are rare, and they are slow to construct the kind of stream networks we see in temperate regions. Where mountains are actively growing, as in the American West, the basins between ranges tend to be bowls, with closed drainage. These basins hold shallow lakes during parts of the year. Only the finest sediment reaches the center of a desert basin: particles of silt and clay. Both wind and water carry this material. Water also brings with it dissolved minerals, and as the desert lakes dry up these minerals come out of solution. Among these are calcite and gypsum, which tend to cement the lake bed mud and turn it hard. Other minerals are salts, mostly halite, the same substance as table salt. Where halite is abundant, dry lake beds turn into salt flats.
The largest salt flat in America is the Bonneville Salt Flats in Utah, a place so flat that you can see the Earth's curvature as you look across it.
Why a Playa? Dry lake beds have many different names around the world but in the deserts of the United States the most common term is playa (PLAH-ya), the same word Spanish speakers use to refer to the beach.
Racing Rock Playa?
Racing Rocks are a geological phenomenon. The stones slowly move across the surface of the playa, leaving a track (wake) as they go without human or animal intervention. Racetrack stones may only move once every two or three years and until recently this phenomena was not seen or measured by man, er, actually a woman until (wait for it.....) GPS!.
The Racing Rocks are moved by strong (up to 90mph) winter winds after a rain which wets the playa just enough to make the clay slippery. The prevailing southwest winds blow to northeast and most of the rock trails are parallel to this direction.
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To log this Earthcache, take an optional photo of yourself or your GPSr near the posted coordinate along Highway 375 overlooking the playa with the rock in the background.
Do Not Approach The Lake Bed If Flooded!
And to demonstrate the educational value of the Earthcache, email answers to the following questions to ARF! at the link below:
1. Which three minerals tend to cement the lake bed mud and turn it hard?
2. What is the texture of the lake bed?
3. On the lake bed is a single rock. Is this rock a racer and why?
4. Using the single rock, estimate the the depth of the occasional flood condition which occurs after a rain or snowmelt.
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Please email answers to:
ARF!
The ET Earthcache series include the most FAVORITED Earthcaches in Nevada! Thanks to everyone who posts a
FAVORITE
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Alamo to Tonopah Earthcaches:
Groom Mining District Rachel, NV (GC2GHE8)
Alamo Breccia Alamo, NV (GC37ZKW)
Playa Goblin Knobs, NV (GC2GP44)
Walker Lane Tonopah, NV (GC36DRD)
Golden Arrow Mine Golden Arrow, NV (GC4QX9J)
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Please do not wait on a reply from me. Simply email the answers and log the Earthcache. FOUND IT logs which do not meet requirements will be resolved quietly.
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