The petroglyphs of Winnemucca Lake, a dry lake bed lying in northwest Nevada, have now been dated, and the carvings are claimed to be the oldest yet known in North America, almost 15,000 years old.

Photo: University of Colorado

The petroglyphs consist of symbols, carved in soft limestone probably by harder volcanic rock fragments, ranging in size from 20 cms to 100 cms in width. A team of scientists led by Larry Benson, of the University of Colorado Natural History Museum in Boulder, claim that they are between 10,500 and 14,800 years old.

The dating method involved radiocarbon testing on the mineral carbonate layers formed when the decorated rocks were submerged. The rocks were exposed - for carving - between about 14,800 to 13,100 years ago, and again from about 11,300 to 10,500 years ago. This, however, does not indicate the time span for the carvings; over a short period of time, or more extended.

Discoveries at the Paisley Cave in Oregon of several pieces of fossilized human feces, or coprolites, dated approximately between 14,400 to 13,000 years ago, currently suggest the earliest dates for human colonization of the Americas, as supported by the genetic evidence. This early wave of colonizers may have been responsible for this rock art.