Saturday, January 21, 2012
Popcorn Rock and Indian Head Rock, were built in the past during times of higher water levels, when upwelling calcium-laden spring water entered the lake along fault zones and mixed with colder, carbonate-rich lake water .
The tufa formations in the Needles area include spread-out mounds composed of interlocking spheres and barrels and tall mounds (towers) reaching elevations 100 m above lake level . Tufa is mainly calcium carbonate, but some tufa deposits contain cells of algae. The variation in composition, density, porosity and crystallinity results in a multitude of forms including encrusting, fiber-forming and branching tufa. Many can be discovered between and around the Needles.
Getting to the Needles
Route 445 along the west side of Lake Pyramid ends at Warrior Point as a paved road and continues on as Indian Land Route No. 2. The dirt road to the Needles has been closed. The “tufa incarnation of the first President of the United States of America,” George Washington Rock, about five miles north of Warrior Point, is a good location to view Wizard Cove and the Needles. Depending on your time, you may start anywhere along the shore and hike north. The tufa mounds can be seen from far away. But remember that you are in desert country: features that look like they are nearby, may still be miles away. Also, you may sink or break in by stepping onto unstable ground, what will further delay your approach.
References and more to explore
 Tufa on pages 116-118 in California Geology by D. R. Harden. Second Edition. Pearson Education, Inc., Upper Saddle River, NJ, 2004.
 Tufa on page 145 in the guide book Geologic and Natural History Tours in the Reno Area by J. V. Tingley, K. A. Pizarro, C. Ross, B. W. Purkey and L. J. Garside. Nevada Bureau of Mines and Geology Special Publication 19, University of Nevada, Reno, 2005.
 Larry Benson: The Tufas of Pyramid Lake, Nevada. USGS, Circular 1267, last updated 2004 [plpt.nsn.us/geology/index.html].
Posted by Axel D. at 9:45 PM