A few years ago, I attended a program by Eugene Hattori at the Nevada State Museum about the incredibly old petroglyphs that were carved into the tufa coating on boulders in the Winnemucca Lake area.
Unlike most Nevada petroglyphs, such as those at Grimes Point that are carved on boulders coated with brown desert varnish, the ones at Winnemucca Lake are carved into the coating of tufa on the surface of boulders that had been under water several thousand years before. Also, unlike petroglyphs on desert varnish-coated boulders, petroglyphs on tufa rock can be dated due to traces of organic material in the tufa.
The western side of Winnemucca Lake is home to several boulders carved with petroglyphs that lie within the Pyramid Lake Indian Reservation. The site was first described by Connick and Connick in 1992. The team, Frances and Robert E. Connick, classified it as unusual, and possibly of very great antiquity.
In 1994, geochemist, Larry Benson determined the designs had been carved into a branch form of tufa, a type of limestone. The research showed that the limestone was deposited between 16,200 and 14,800 years ago, but no specific date for the carvings was suggested.
Tufa is a calcium carbonate crust that typically formed only on rock formations that were submerged under the water of ancient Lake Lahontan for relatively long periods of time as lake levels rose and fell.
In 2013, a team of researchers from the University of Colorado at Boulder (including Benson) collected carbonate crust and shallow-water algal formations from the site. They then used dating strontium isotope analysis and total inorganic carbon data from a core in Pyramid Lake to establish a window of when the lake level was low enough to allow human access to the rocks. Sedimentary cores were collected from nearby Pyramid Lake and subjected to analysis to determine rise and fall of the waterline over time.
More precise methods of dating would have required taking scrapings from the grooves of the petroglyphs, which was not allowed by the Pyramid Lake Paiute Tribe. However, Benson was allowed to use non-invasive techniques to examine the petroglyphs that allowed him to work to the side of the carvings.
The broad consistencies among the various dating methods allowed the research team to conclude the petroglyph rocks were above the waterline, and thus available for carving, from 14,800 and 13,200 years ago and again between 11,300 and 10.500 years ago.
Additionally, the younger date range is consistent with the date of textiles previously found within the Winnemucca sub-basin dated as old as 10,700 years ago and the date of various human artifacts previously found within the Lahontan Basin dated from 11,000 to 10,400 years ago. The younger dates also align with the estimated age of the Spirit Cave mummy found nearby.
Either date range would make the petroglyphs the oldest found in North America to date. To put all this in perspective, the petroglyph carvings near Winnemucca Lake are over twice as old as the Egyptian pyramids. The rocks include both simple petroglyphs such as straight lines and swirls and more complex petroglyphs that resemble trees, flowers or the veins of a leaf.
There is also an intricate diamond pattern on one rock. The smallest are approximately 8 inches in width, while the largest are 3 feet. Grooves are approximately .4 to .8 inch deep. The carvings are deeper and larger than those typically found in the southwestern United States.
The meaning of the carvings is unknown. The Connick team suggested the petroglyphs could represent meteorological symbols such as clouds and lightning. Benson’s team suggests the Winnemucca Lake petroglyphs share several distinctive features in common with the Long Lake petroglyphs that are not found in more recent petroglyphs. How the petroglyphs were created is not known, but hard volcanic rock was possibility used to chip away at the softer carbonate formations on the boulders.