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Skull Valley springs spout from marvel of desert geology

04 Aug

The scale of Skull Valley’s secret water world is quite evident when viewed from the Stansbury foothills.  It’s much less apparent at ground level, where sporadic mirror-like surfaces visible from the highway are often the only hints of its existence.  The closure of most recreation roads on the east side of the highway for post-wildfire restoration offers an excellent opportunity to pay this unique ecosystem the attention it deserves.

A tributary runs through Skull Valley near Horseshoe Springs. Looking down on Skull Valley from the Stansbury Mountains shows a secret water world in the desert (photo by Clint Thomsen).

The following originally appeared in the July 27, 2010 edition of the Tooele Transcript Bulletin.

Nothing says “desert” like a mouthful of dust.  Or an eyeful or a couple nostrils full, for that matter.  You might say I should have known better than to get out of my car so soon after stopping along a dirt road in the dead of summer—that I should have considered the mile-long dust wall that was cresting behind me like a giant breaking ocean wave.  I blame the lapse in judgment on curiosity.  Curiosity and the genius who posted a road sign typed in an 8-point font.

The sun had barely risen above the Stansbury Mountains and Skull Valley was awash with soft light.  I was about a mile out on the road that bisects the valley and leads to a place called 8 Mile Spring on the flanks of the Cedar Range.  No sooner had I shut my car door than the raging wall of alkaline particulate swallowed me whole.

Call it evidence of the desert’s endless ability to overwhelm the senses—a poignant reminder that out here things are rarely as they seem.

Take the landscape, for example.  At first glance, Skull Valley can appear to be completely desolate.    But a closer look reveals an array of natural oases where unorthodox fauna abound.

The scale of Skull Valley’s secret water world is quite evident when viewed from the Stansbury foothills.  It’s much less apparent at ground level, where sporadic mirror-like surfaces visible from the highway are often the only hints of its existence.  The closure of most recreation roads on the east side of the highway for post-wildfire restoration offers an excellent opportunity to pay this unique ecosystem the attention it deserves.

At the heart of Skull Valley’s wetland system is a collection of geothermal springs that issue warm, brackish water.  Though understated, these springs are a major component of Skull Valley’s geology.  They’re also the source of the valley’s original namesake—Spring Valley.

Historians haven’t definitively concluded on the reason for the name change, but it’s possible that “Skull Valley” also derives from the springs.  According to legend, Spring Valley became Skull Valley upon the discovery of an inordinate amount of buffalo skulls on the valley floor near the springs.  Local historian Don Rosenberg thinks an unusually harsh winter was to blame.

Rosenberg theorizes that heavy snows drew herds away from the mountains and down to the springs, whose warm surrounding terrain remains snow-free all year.  Once the all the exposed grass around the springs was eaten, the herds had nowhere else to turn and died where they stood.

Understanding the science behind these springs can be daunting—especially since no exhaustive study has been conducted on them.  Worse yet, geology is yet another facet of real life where my Political Science degree has proven less than useful.  Terms like “forced convection” and “Quaternary fault scarps” make me quake in my boots.

An unnamed pool near Iosepa. Look past the moss lining the pool-- that's crystal clear brackish heaven in there (photo by Clint Thomsen).

Fortunately, the guys at the Utah Geological Survey regularly make painstaking efforts to demystify these concepts for me.  UGS geothermal expert Robert Blackett described the recharge/discharge cycle to me as a function of precipitation, gravity and pressure.

The process begins in the mountains with rain or snow melt.  While much of this precipitation travels down toward the valley in streams, Blackett said a certain percentage percolates into the ground and seeps slowly downward through the bedrock via fractures.  When the water hits a geologic dead end, it’s forced back upward and is discharged from the ground as a spring.

In the case of thermal springs, water is heated by the earth’s interior as it travels.  A thermal spring’s discharge temperature depends on distance traveled and obstacles encountered along the way.  Deep-reaching water that rise quickly without mixing with cooler water discharges as a hot spring.

The Skull Valley springs are believed to mix with cool ground water before discharging as warm springs.  The National Oceanic and Atmospheric Administration (NOAA) defines a warm spring as any spring ranging in temperature between 68 and 122 degrees Fahrenheit.  The average temperature of the Skull Valley springs is 70 degrees Fahrenheit—about 8 degrees cooler than the average swimming pool.

The temperature and water chemistry differ slightly from spring to spring, but some are probably interconnected and all are brackish from the minerals they’ve picked up along the way.  Several support populations of planted fish.

According to UGS documents, Skull Valley’s 8 major thermal springs collectively discharge 30,000 to 50,000 acre-feet of water per year.  Discharge flows northward and eventually drains into the Great Salt Lake.  Blackett said the recharge cycle for thermal springs tends to much longer than that of cool springs.  Citing the lack of study of the area as a caveat, Blackett said it’s possible that the warm water discharged from the Skull Valley springs fell as precipitation as far back as the last Ice Age.

If you’ve been to Skull Valley, you’ve probably stopped at the twin Horseshoe Springs, which flow together to form a distinctive inverted “U.”  I grew up swimming in the deeper north spring.  Diving to the source with goggles was always an eerie endeavor, as it very literally is a portal to another world.

The Horseshoe Springs were designated a Federal Wildlife Management area in 1990.  The pools sustain a small population of carp and largemouth bass.  Fishing is permitted, but good luck catching anything.  This hole is famous for its belligerent fish.  Many an angler wonders if the bass there haven’t simply caught on to our hook-and-bait scam.

On my way home that morning, I stopped at Horseshoe Springs to pay regards to the elusive bass.  I considered jumping in for old time’s sake, but didn’t.  Hearing the gurgle of water against this barren backdrop was satisfying enough.

TRIP TIPS

Some of Skull Valley’s springs are visible on the valley floor west of SR-196.  Some are located on private property, others on BLM land.  Horseshoe Springs is publically accessible year-round.  Bug repellent is a must. For more information, contact the BLM at (801) 977-4300.

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3 responses to “Skull Valley springs spout from marvel of desert geology

  1. Michelle Powell

    August 4, 2010 at 2:34 pm

    Another great article. THANKS! :)

     
  2. Tom Clark

    August 25, 2010 at 4:58 am

    Thanks so much for sharing all of this information and insight. I’m a frequent visitor to Skull Valley and am always eager to learn as much about it as I can. Tried to find 8 Mile Spring yesterday but was unsuccessful – lots of little side roads off the main road made it tricky to know which way to go. Maybe next visit.

     
    • bonnevillemariner

      September 7, 2010 at 6:59 pm

      Tom, don’t worry– 8 Mile Spring isn’t much to look at, but if you ever try to find it again, just stay on the main road until it curves with the mountain. Look closely to your right and you’ll see a patch of marsh grass that looks out of place. That’s the runoff. The actual spring flows from a rusted metal pipe on the hillside. Thanks for dropping by!

       

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