Saturday, January 14, 2012

Popcorn Rock at Pyramid Lake

Popcorn Rock is a tufa structure at Pyramid Lake.The natural composition of round-shaped rocks, built from calcareous substances and partially eroded, gives the appearance of a giant popcorn.

Popcorn Rock and other tufa structures have been formed by precipitation of calcium carbonate. When water levels were much higher than they are now and Pyramid Lake was part of Lake Lahontan during the ice age, the sites, which exhibit tufa towers and mounds today, were under water. Many tufa features line up along fault zones. It is assumed that, in the past, warm calcium-laden spring water spilled out into the colder water of Lake Lahontan: tufa features, such as Popcorn Rock, formed at this interface where mineral water of different temperature and composition combined [1]. Gradually diverse calcium carbonate sculptures were deposited and agglomerated into today's shapes around and beyond the current reach of Lake Pyramid.

Finding Popcorn Rock
Popcorn Rock is located at the southern end of Pyramid Lake (near the Guanomi Mine) along Route 446 between its intersection with Route 447 at Nixon and its intersection with Route 445 further north. See the section Getting to Pyramid Lake in the previous post, describing how to get to the lake from Wadsworth (near Fernley) or from Reno and Sparks.

Popcorn Tufa Reference
[1] 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.

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