Petroglyphs and Pictographs

Throughout the American Southwest indigenous peoples have left behind many clues of their existence including oral histories, ceramics, projectile points, platform mounds, canal systems and most mysteriously rock art.
"Spiral" Petoglyph in South Mountain Preserve

Who?: The Hohokam
The Mountains of the Salt River Valley contain many fine examples of rock art. This rock art was created by the Hohokam people and other indigenous tribes of the Sonoran Desert. Incredibly, More than 550 major rock art sites have been recorded in the Sonoran Desert thus far (Bostwick 19). The term "Hohokam," is Pima in origination and refers to the ancestors of native peoples that have inhabited the Salt River valley since 300 BC. The Hohokam were agriculturalist who created amazing adobe structures, built vast canal systems, and created these intricate rock art designs. See more on Hohokam history.


In South Mountain Park Preserve the indigenous people, or Hohokam, created both pictographs and petroglyphs. Pictographs are created by using pigments to paint images onto the surface of rock faces. These pigments could have been made from plant materials, minerals, charcoal or blood. Pictographs usually take on the same style and image as petroglyphs, but are very scarce and hard to find because of wear by natural elements.

The most common form of rock art found in South Mountain Park Preserve are petroglyphs; Petro meaning "rock" and glyph meaning "carving" or "drawing" in Greek. Petroglyphs are created by using a hammer stone and chisel to peck away the outer surface, or patina, from rocks and boulders. This is referred to as the "percussion" method. This exposes a lighter colored surface of mineral below, allowing designs and images to appear on the rocks surface. In addition to the "percussion" method, "Abrading" was also used by indigenous people to slowly scratch away the rocks surface using a stone; leaving a much smoother texture behind.

South Mountain Animal Petroglyphs


Desert Varnish: (Patina)
Since the rocks patina or "desert varnish" can take thousands of years to form on the rocks surface, some petroglyphs can be seen until a new patina forms. Rock varnish is created when floating pieces of mineral matter, such as iron oxide, rest on the rocks surface and are cemented in place by bacterial secretions; leaving a dark varnish. It is thought that many of the petroglyphs found in South Mountain are almost 1,000 years old and some date back as far as 300AD! In time, most of the petroglyphs will turn as dark as the surrounding rocks surface and disappear forever!

Forms: (styles)

Petroglyphs take on many different forms including: zoomorphic (animal), anamorphic (human) and geometric designs (textile). Many of the zoomorphic forms seen in South Mountain park preserve include: birds, coyotes, dogs, snakes, Gila monsters, chuckwallas, and deer. Some of the Geometric forms include: spirals, crosses, pipettes, and circles. The anamorphic motifs usually involve the figures dancing, hunting, or flute playing.

Meaning: (interpretation)
There are many theories about the meaning of these incredible etchings. Some theorize that they were used as mnemonic devices to remember significant dates, events, and oral histories of the tribe. Others believe that these mysterious marks could have been used to mark trail routes, water sources, culturally significant cites, and territorial claims. While other experts believe that these amazing and time consuming etchings could have held ceremonial or religious significance.

While some disagree on the purpose of these petroglyphs most feel that they would have been created as part of a ceremony or vision quest involving the tribal shaman and would have been of great importance considering the tremendous effort needed to create such works. Regardless, these amazing images have been left for us as gifts and clues to enjoy and ponder. Petroglyphs serve as a portal back in time and help to solve the mystery, and bridge the gap between the indigenous peoples of the Salt River Valley and our culture today.

We are just beginning to scratch the surface of the rock art mystery. A tremendous amount of continued research and archeology is necessary to keep peeling away the layers and gain a further understanding of these amazing features. Please help us protect these significant sites from vandalism.

* Attention: It is illegal to collect or vandalize petroglyph sites! Please inform law enforcement if you become aware of such activities.*

Arizona Cave Protection Law
13-3702. Defacing or damaging petroglyphs, pictographs, caves or caverns; classification

Section A:
(1) Breaks, breaks off, cracks, carves upon, writes or otherwise marks upon or in any manner destroys, mutilates, injures, defaces, removes, displaces, mars or harms petroglyphs, pictographs or any natural material found in any cave or cavern; or
(3) Disturbs or alters the natural condition of such petroglyph, pictograph, cave or cavern or takes into a cave or cavern any aerosol or other type of container containing paints, dyes or other coloring agents; or

Section C:
Defacing or damaging petroglyphs, pictographs, caves or caverns is a class 2 misdemeanor. (A Class 2 Misdemeanor has a fine of up to $ 750.00.)

Works Cited

- Andrews, John P., and Todd W. Bostwick. Desert Farmers at the Rivers Edge: The Hohokam and Pueblo Grande. Phoenix: City of Phoenix Park, Recreation, and Library Department, 2000.
- ArizonaCave Survey. 2006. 4 January 2008 <>
- Bostwick, Todd W, and Peter Krocek. Landscape of the Spirits: Hohokam Rock Art at SouthMountainPark. Tucson: The University of Arizona Press, 2002.
- Welsh, Elizabeth C. Easy Field Guide to Southwestern Petroglyphs. Phoenix: American Traveler Press, 1995.