View of Trona Pinnalces
Views of the Trona Pinnacles

How the Pinnacles were formed
When glaciers were active between 10,000 and 100,000 years ago, Mojave Desert weather was cool and damp.  The Owens River was also swollen by melting glaciers in the Sierra Nevada Range, and this river filled a string of lake in the desert basins, including the basin known as Searles Valley.  But these desert basins were closed, having no outlet to the sea, and only overflowed from one to the next depending on the balance between river flow and evaporation from the surface of the lakes.  Therefore, any minerals leached from the rock in the drainage basin of the Owens River were trapped in these lakes.  And for much of this period, Searles Lake was the end of this chain of lakes so most of these minerals became trapped there.

As the level in Searles Lake began falling at the end of this era, the minerals in the water, a major component of which was sodium carbonate, began to concentrate.  Concentrating the minerals also made the water denser.  At the same time as the lake level was falling, ground water that had been help up by the high lake levels began slowly moving beneath Searles Lake from land to the south and west.  In the area of the Pinnacles there were long fractures penetrating the clays forming the bottom of the lake.  These allowed the ground water to bubble up through the lake waters.  Much of the ground water beneath the Pinnacles was high in hardness, principally soluble calcium salts, and still is today although it no longer flows to the surface.  When the high calcium water bubbled up through the lake water that had been enriched in sodium carbonate, calcium carbonate (more commonly known as limestone or calcite) precipitated.  This formed the tufa towers we now call the Pinnacles.  If you look closely, you can see the paths that the ground water took as it bubbled up through the pinnacles.

For an Area Description, Directions on How to Get There, and Considerations in Planning Your Visit, see the  BLM Web Page on the Pinnacles .

Go to  Local Areas of Interest

Searles Lake Gem and Mineral Society
P. O. Box 966
Trona, CA   93592-0966
Phone (760) 372-5356

Home  Site Map  | GEM-O-RAMA Site Map  |  Revised 04/24/2004

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