What is a Petroglyph?

Hundreds, and even thousands of years ago, the native people living in North America developed a method of placing pictures on boulders. This left an impression that was able to last for as long as 16,000 years in some cases. Using a strong rock and a hammer stone, the artist, usually a shaman or medicine man, would chip away at the boulder. Once the dark outer layer of the boulder was removed, there was a lighter colored layer that stood out. Over time, even this lighter layer will weather and erode, or become darker as small wind blown particles of sand adhere to the surface.

The reason for the petroglyphs has been mostly determined from actual historical accounts and records, but there still could be many reasons that archaeologists will never know. The most common belief is that the shaman went into a trance or meditation. This was his 'vision quest', where he received a vision of a spirit guide. He then came out of his trance and chipped a petroglyph of what he saw. Some petroglyphs are of animals, such as big horn sheep, horses, or mammoths, but some are also of human forms. Most of the pictures are highly stylized, so their exact meaning is obscure.

Interestingly, the petroglyphs themselves can be used to date the time of their placement. A hunting instrument known as an atlatl was used before the bow and arrow was introduced, therefore a picture of an atlatl or a bow and arrow can give an approximate date. The same goes for pictures of horses or even guns. There have been petroglyphs of animals that became extinct more than 15,000 years ago. Certain images had specific meanings attached to them. For instance, the big horn sheep was believed to represent rain, therefore the rain-shaman would depict the sheep in hope of bringing rain to the parched land.

There are still quite a lot of areas in the United States to see petroglyphs, but these are mostly in the deserts. The states of Nevada and California are well known for their caches of the rock drawings, which tend to be located within narrow rock canyons or in the mountainous terrain. Two locations accessible to the public are Hidden Cave/Grimes Point in northern Nevada, near Fallon, and China Lake/Oso Mountain in Eastern California. There are generally tours put on by local museums, which are excellent at providing background information about the local tribes.