in the river valleys of western Montana, British Columbia, northern Idaho, and Washington, are an artistic record of Indian culture that spans thousands of years. Collectively called rock art by the scientists who study them, these drawings are most often carefully executed pictures of humans, animals, and spirit figures that were made as part of the rituals associated with religion, magic, and hunting.
Rock art in the Pacific Northwest was first noticed by early explorers. Before the turn of the century, government-sponsored expeditions searching for wagon and railroad routes through the region noted rock art at Lake Chelan, along the lower Columbia River near Umatilla, and in northern Idaho. Soon after, anthropologists and other scientists began studying some of these sites. James Teit, an ethnologist who recorded the cultures of Columbia Plateau Indian tribes in British Columbia and northern Washington between 1890 and 1920, interviewed natives who had painted some of these pictures and asked why they had done so (Teit 1928). Since then, his work has been a key to all serious rock art research in the region. Since 1950, numerous scientific articles and two small books about Columbia Plateau rock art have described and discussed the paintings and carvings of many areas in the Pacific Northwest (Boreson 1976; Cain 1950; Corner 1968; Keyser and Knight 1976; Loring and Loring 1982; McClure 1978).
Despite this long history of scientific interest in Columbia Plateau rock art, the public remains relatively unaware of these paintings. Except for occasional newspaper or magazine articles, and limited interpretation of a few sites, little information on rock art has been made available to nonscientists. One result has been the spread of misinformation by sensationalist writers, who have suggested that these drawings are maps or “writing” left by Chinese, Norse, Celtic, or other pre-Columbian explorers.
More serious, however, is that current residents of and visitors to the Pacific Northwest miss the opportunity of understanding and appreciating rock art as a part of our region’s rich cultural heritage. This has led to the defacement (and even the destruction) of some sites by unthinking vandals who obliterate the original art with spray-paint scrawls. Thus, my purpose in writing this book is to help interested persons understand the age, meaning, and function of this art. I hope that this will lead to public appreciation of and concern for these irreplaceable art treasures of our past.
What Is Rock Art?
Simply put, rock art can be defined as either engravings or paintings on nonportable stones (Grant 1967, 1983). Because it is the subject of scientific study, a set of specialized archaeological terms and a technical vocabulary convey exact nuances of meaning to professional scholars. These terms can be confusing to the lay reader, and since the primary purpose of this book is to provide an overview of Columbia Plateau rock art and to describe in general its origin, function, and age, I have used a minimum of this professional jargon. Some terms cannot reasonably be avoided, however, due to the specialized nature of the subject matter. Thus, I define here six terms which may need clarification: petroglyph, pictograph, anthropomorph, zoomorph, rock art style, and rock art tradition. Each of these can also be found in the glossary, which contains a few other specialized terms used occasionally throughout the book.
Petroglyphs
Petroglyphs are rock engravings, made by a variety of techniques. In the Pacific Northwest, pecking was the most common method: the rock surface was repeatedly struck with a sharp piece of harder stone to produce a shallow pit that was then gradually enlarged to form the design. Some Columbia Plateau petroglyphs were also abraded or rubbed into the surface with a harder stone to create an artificially smoothed and flattened area contrasting with the naturally rough-textured rock. Pecked designs were sometimes further smoothed by abrading.
A few Pacific Northwest petroglyphs were made by scratching the rock with a sharp stone flake or piece of metal to produce a light-colored line on the dark surface. Some shallow scratches are now nearly invisible, having weathered over several hundred years. Others were deepened to form distinct incisions still readily apparent. A few petroglyphs show a combination of techniques; most common are animal figures with abraded bodies and scratched legs, horns, or antlers.
Columbia Plateau petroglyphs are most often made on basalt, a hard, dense volcanic stone. The weathered surface of basalt is a dark, reddish-brown to black patina, or “crust,” several millimeters thick. Underneath this patina the stone is a lighter color, ranging from yellowish brown to dark grey. Prehistoric artists engraved deep enough to reveal this un-weathered interior stone so that designs would stand out against the darker background. Reweathering of designs exposed in this way provides a clue to help in dating some petroglyphs.
Pictographs
Pictographs are rock paintings. On the Columbia Plateau these are most often in red, but white, black, yellow, and even blue-green pigments were sometimes used. Polychrome paintings are uncommon, but a few do occur throughout the region. Most frequent are the red and white polychromes of the lower Columbia River and Yakima valley.
Pigment was made from various minerals. Crushed iron oxides (hematite and limonite) yielded red—ranging from bright vermilion to a dull reddish brown—and yellow colors. Sometimes these ores were baked in a fire to intensify their redness. Certain clays yielded white pigment, and copper oxides blue green. Both charcoal and manganese oxide produced black. Early descriptions indicate that Indians mixed crushed mineral pigment with water or organic binding agents, such as blood, eggs, fat, plant juice, or urine, to make paint.
Pigment was most commonly applied by finger painting: finger-width lines compose the large majority of pictographs throughout the area. Some paintings, done with much finer lines, indicate the use of small brushes made from animal hair, a feather, or a frayed twig. Still others were drawn with lumps of raw pigment (much like chalk on a blackboard) or grease-paint “crayons.” These pictographs have a characteristic fine-line appearance, but the pigment appears somewhat unevenly applied in comparison with the small brush paintings.
How this paint has survived on open exposed cliff faces, where pictographs are usually found, has long been the subject of scientific debate. Early scholars, presuming that the paint would fade rapidly, argued that all of these paintings had been done during the last two hundred years. Several reported significant fading at some sites, and even suggested that none of these paintings would last beyond a few more years. Fortunately, they have been proven wrong: scientists have recently discovered evidence that the paintings are not disappearing, as originally thought. Photographs taken at several sites over spans of as much as seventy-five to one hundred years indicate that pronounced fading is not usually a problem. Often, “faded” pictographs are found to have been destroyed by road construction, inundated by reservoirs, or covered by road dust or lichen. When affected only by natural weathering, paintings at hundreds of sites remain as bright today as when they were first discovered.
Recent research by Canadian scientists (Taylor et al. 1974, 1975) has demonstrated why these rock art pigments are so durable. When freshly applied, the pigment actually stains the rock surface, seeping into microscopic pores by capillary action as natural weathering evaporates the water or organic binder with which the pigment was mixed. As a result, the pigment actually becomes part of the rock.
Mineral deposits coating many cliff surfaces provide a further “fixative” agent for these paintings. Varying types of rock contain calcium carbonates, aluminum silicates, or other water-soluble minerals. Rain water, washing over the surface of the stone or seeping through microscopic cracks and pores, leaches these naturally occurring minerals out of the rock. As the water evaporates on the cliff surface, it precipitates a thin film of mineral. This film is transparent unless it builds up too thickly in areas with extensive water seepage. In these instances the mineral deposit becomes an opaque whitish film that obscures some designs, the reason that some pictographs do actually fade from view. However, microscopic thin section studies show that, in most instances, staining, leaching, and precipitation have actually caused the prehistoric pigment to become a part of the rock surface, thereby protecting it from rapid weathering and preserving it for
