“Rock art” is the collective term for a variety of forms of visual representation made on natural rocky surfaces (boulders, cliff faces, cave walls, etc.) and are found throughout the world. Pictographs and petroglyphs represent the two main techniques used to make rock art. Pictographs are made through an additive process, where they are applied to the rock surface, and include paintings, charcoal drawings, stencils, prints. Petroglyphs are made by a reductive process, in which they are cut into the rock by engraving, pecking, incising or abrasion. Rock art can also take the form of geoglyphs (large ground figures made by piling up rocks into patterns) and intaglios (large ground figures made into patterns by scraping the surface of the ground away). These types are present in Nevada, but are rare compared to the petroglyphs and pictographs, which are the state's most common types of rock art.

Nevada rock art is found in a wide variety of landscapes and locations throughout the state. Few sites in Nevada provide clear contextual indications of their date of production and period of use, such as stratigraphic superimposition by datable materials. Very few rock art sites offer thematic indicators of their age, such as the depiction of extinct animals, or the portrayal of diagnostic artifacts which forms the basis for identifying historic period rock art (for example the portrayal of wagons, people wearing cowboy hats and riding horses, etc.). Most sites can not be convincingly dated from a consideration of the imagery represented and so a means of directly dating rock art by scientific methods is the subject of intense research. In recent years advances in scientific dating methods have been made but there is currently little agreement on the validity or reliability of any single method. In spite of the current inability to reliably date rock art's production or its period of use, there is little doubt that rock art has been created in Nevada for as long as the region has been occupied by people. Many Native Americans believe that their ancestors were created here at the beginning of time, but most archaeologists agree that people have lived in Nevada for at least 10,000-12,000 years.

Of the pictographs and petroglyphs that are found in Nevada, petroglyphs are by far the more common of the two. This may be the result of differential preservation as most of Nevada's pictographs are situated inside caves, rock shelters or other contexts, which afforded some measure of protection from the elements. This biased distribution does suggest that potentially many more pictographs existed in the past in unsheltered contexts, but these have simply weathered away and did not survive into present.

Pictographs

Colored minerals were used to make pigments for pictographs (ocher being the most common, but also gypsum, charcoal, etc.). These minerals were ground very finely and mixed with a wetting medium (called a binder), such as water. There are instances of proto-historic and prehistoric pigments being made using pulverized sappy plants, blood, or other organic materials. This would allow the pigment to be directly dated using standard Accelerator Mass Spectrometry (AMS) radiocarbon dating techniques. The liquid pigment was applied to the rock surface using the fingertip or hand or possibly sticks with frayed ends or some other type of “brush.” Very few studies of pictograph materials or rock art dating have been conducted in Nevada, although these types of analyses have been done in other parts of North America.

Petroglyphs

Petroglyphs are produced by simply removing the very thin layer which covers the outer surface of rocks. This can be done by incising (which produces very fine lines, often referred to as “scratched”), abrading (or repeatedly rubbing the surface), or pecking (repetitive tapping or pounding) the rock surface to break the outer surface away. Often, this outer surface (either the rock's patina or desert varnish) is darker in color than the interior of the rock and so the contrast in color between the darker outer surface and the engraved area makes the petroglyph visible.

The tool used to produce petroglyphs would vary depending on the type of petroglyph being made. Thin rock flakes, like those produced during the manufacture of projectile points, can be used to make scratched or incised petroglyphs. There is some suggestion that scratched petroglyphs were made into historic times using metal instruments such as a nail or a knife. Very close examination of the incised line may reveal traces of metal within them verifying their historic age.

Both pecked and abraded petroglyphs can be produced by using any rock that is as hard as, or harder than, the rock being engraved. Many of the rock types in Nevada are extremely hard (such as limestone, granite or basalt) while others are less dense (such as sandstone or volcanic tuff). There is also some suggestion that very hard rock types such as quartz were the preferred pecking stone for creating petroglyphs.

Rock Art Imagery

The images produced in both pictographs and petroglyphs in Nevada are similar. Both types of rock art are primarily made up of what might be termed “non-representational” motifs, including geometric forms such as grids, circular forms, wavy lines, dots, etc. Such motifs are found throughout the world and form the basis of all visual traditions of art. This makes interpretation of such imagery very difficult and the tendency to look for “universal” meaning is strong. However, one need not look far to find that the meaning of a simple geometric form changes from place to place around the world and through time.

By giving a motif an interpretive label (e.g., calling a wavy line a “snake” or “river” or “path”) rather than a neutral descriptive label creates meanings that have more to do with the contemporary observer than the rock art's original makers and users. Additionally, the act of creation is only the first stage in rock art's cultural-use life—through time rock art is encountered and reinterpreted by later peoples, so its “meaning” is not necessarily inherent, but is instead constructed, negotiated, and reinterpreted for as long as it is perceived as having cultural resonance. This is an ongoing, potentially non-linear process, with rock art deriving cultural and emotional power despite discontinuities in use. As noted by Quinlan and Woody, through time “the discourses articulated by and through rock art become increasingly distanced from the intentions of its original makers and users,” a process contemporary observers contribute to in making subjective identifications of rock art imagery.

Representational motif types present in Nevada rock art include apparent depictions of people (anthropomorphs), animals (zoomorphs), and plants. These are deceptively difficult to interpret, because the depiction of an animal, for example, may not refer to the animal depicted or may contain additional symbolic connotations. However, at least one part of the meaning of “representational” motifs may have to do with their similarity to the real world objects they seemingly signify, meaning that such imagery can still be apprehended at one level.

Anthropomorphic motifs are found represented in a wide variety of ways, from simple schematic stick-figures (which predominate throughout the state), to more elaborately executed types. Only a small percentage of the anthropomorphic motifs found in Nevada include characteristics which indicate whether the image was intended to signify gender. Although researchers have a tendency to designate all anthropomorphs as “male,” this is not verifiable unless the sex of the image is clearly indicated, and in the vast majority of cases it is not indicated. Some anthropomorphic motifs appear to include clothing or other ornamentation, such as elaborate headgear or jewelry (e.g., necklaces or earrings). In some cases this elaboration indicates a specific “style” (attributable to a specific time and place), such as Fremont or Pahranagat style anthropomorphs. Both of these very distinctive styles are found in the eastern (and south-eastern) portion of the state.

Identification of the species signified in zoomorphic motifs is difficult because a simple signification of a type of animal was not necessarily the original intent or interpretation of a particular zoomorphic form. However, it is apparent that a range of species were depicted in rock art—some were represented more commonly than others, e.g., large mammals (e.g., deer or antelope) and reptiles (e.g., lizards or turtles), and some were rarely the subjects of representation (e.g., fish, birds, and insects). By far the most common zoomorphic motif found in Nevada, and the desert west more generally, is the bighorn sheep. Also of some interest is what animals are not found in rock art, such as rabbits or other small mammals, except for coyotes or dogs which are also sometimes found depicted. Animals of all types figure prominently in the stories and lives of Indigenous peoples, so it is difficult to explain the very clear preference for the bighorn sheep as the subject of rock art production.

The distribution of representational versus non-representational imagery in the rock art of Nevada shows a relatively clear pattern. While representational imagery is found throughout the state, it occurs more frequently in the eastern and the southern parts of the state, as does rock art imagery identified as historic in date by its themes (e.g., wagons and figures in cowboy hats).

Natural weathering and deposition will eventually lead to the destruction of virtually all rock art. But unfortunately, human action and explosive population growth are the greatest immediate threats. The study of rock art in Nevada is an emergent field and much research remains to be done. But like rock art found elsewhere, the images are compelling and inspire great interest and speculation among those who encounter them.