naturally occurring things. Of course, no art is composed exclusively of only naturalistic, stylized, or abstract forms, but classification is determined by the type of designs that predominate (fig. 1).
Pacific Northwest rock art is primarily naturalistic, with the exception of the Long Narrows and Yakima polychrome styles localized in the lower Columbia area near The Dalles, Oregon, and a few pit and groove style sites scattered throughout the region. Most Columbia Plateau rock art shows simple stick figure humans and block-body animal figures, rayed circles or arcs, and tally marks. Geometric abstract figures occur in smaller numbers. Frequently, humans and animals are arranged in a composition, often with an associated geometric design such as a rayed arc, circle, or group of dots. The resulting structured composition appears to portray some sort of relationship between naturally occurring objects.
In the lower Columbia area two significantly different art styles—the Long Narrows and Yakima polychrome styles—occur. Dating from approximately the last thousand years, these drawings show an increasing stylization of the human form that culminates in the portrayal of humans and spirit beings as complex mask designs, often with grotesquely exaggerated features. Some animal forms also become more stylized, and polychrome rayed arcs and concentric circles become major components. Apparently Northwest Coast art traditions, which show a somewhat similar evolution of stylization, heavily influenced these two styles. Quite likely, the Columbia River’s use as a major prehistoric trade route from the coast to the interior was partly responsible for the evolution of this stylized art in The Dalles region.
Highly abstract art is not common on the Columbia Plateau. Throughout the region, occasional sites have drawings composed almost exclusively of cupules, dots, and meandering lines; rarely are humans or animals depicted. These sites appear most closely related to the curvilinear abstract art called pit and groove and the Great Basin abstract style that occur throughout the western United States, primarily in the Great Basin area of Nevada and California.
1. Chart of rock art styles
Dating Rock Art
Determining the actual age of most Columbia Plateau rock art sites is difficult to do with certainty, except in instances showing horses or other objects of known historic age. However, a variety of techniques, in combination with the study of stylistic evolution, can sometimes establish relative ages. Six major factors provide clues to general dating of Columbia Plateau rock art: (1) association with dated archaeological deposits, (2) association with dated portable art, (3) portrayal of datable objects, (4) superimposition of designs, (5) patination, and (6) weathering (McClure 1979a, 1984).
Association with Dated Archaeological Deposits
Occasionally, sediment containing dated archaeological items will bury a rock art panel. This may occur in a rock shelter or on an open site where sediment builds up against the rock surface, or when a portion of a rock art panel falls from a vertical surface into an archaeological deposit below. Neither occurrence is especially common, since both require the propinquity of rock art and living areas, rapid deposition of sediment, or partial destruction of the site.
Two examples of buried rock art provide dating clues for the Columbia Plateau. In south-central Oregon, a deeply carved panel of abstract petroglyphs is partially covered by a deposit containing ash from the volcanic explosion of Mount Mazama that formed Crater Lake sixty-seven hundred years ago (Cannon and Ricks 1986). Thus this site demonstrates that Pacific Northwest Indians must have been making abstract petroglyphs before this early date. Of more direct relevance to Columbia Plateau rock art was the discovery—in Bernard Creek Rockshelter in Hells Canyon on the Snake River—of a spall, from the rock shelter wall, that bore traces of red pigment. The painted spall was found in a level that dated between six and seven thousand years ago (Randolph and Dahlstrom 1977). Although it could not be matched to any paintings still visible in the shelter, the fragment does demonstrate that Columbia Plateau Indians have painted pictographs for a very long time.
Association with Dated Portable Art
Many of the ancient Paleolithic paintings and carvings in the famous caves of France and Spain can be fairly securely dated because they closely resemble engraved designs on animal bone that have been found in dated archaeological deposits. In these cases, the portable art and the rock art are sufficiently similar in style and technique to infer that they are contemporaneous. Unfortunately, on the Columbia Plateau portable art is not often found in well-dated contexts, but a few examples are known. Probably the most definitive are near The Dalles, where a number of Tsagiglalal carvings have been found in cremation burials that date between A.D. 1700 and A.D. 1800, and almost identical Tsagiglalal petroglyphs occur on nearby cliffs. Certainly, given the stylistic complexity of this figure, both the portable and rock art examples must be of the same age.
Elsewhere at sites along the middle Columbia, archaeologists have recovered a few pieces of stone and bone sculptured in human and animal form. Some of the human forms show distinctly bared teeth; some humans and animals have ribs clearly shown. All examples with teeth or ribs date within the last twelve hundred years. In the same region are also occasional rock art portrayals of human and animal figures with teeth and ribs. McClure (1984) argues convincingly that these rock art depictions date to the same time period as the carved portable objects. Finally, at an occupation site in southern British Columbia, a small, cylindrical stone painted with red dots and lines was recovered from a context more than two thousand years old (Copp 1980). The designs would fit in any of the area’s pictographs, indicating that simple geometric paintings are of considerable age in the region.
Portrayal of Datable Objects
Rock art from the northern Great Plains region of Alberta, Canada, Montana, and South Dakota shows thousands of historic items, including horses, guns, wagons, European Americans, and buildings. Since the dates at which these objects were brought to the area are known, the rock art is dated to the same time period. Likewise, rock art on the north Pacific coast shows sailing ships that can be reliably dated to historic times.
On the Columbia Plateau, approximately thirty sites show examples of horses or mounted humans (Boreson 1976; McClure 1979a). The drawings include both pictographs and petroglyphs, and occur in all areas of the region. We can reliably date these depictions after about A.D. 1720, when horses were first introduced onto the Columbia Plateau by Indians who had obtained them from Spanish settlements in New Mexico (Haines 1938). A few sites also contain drawings of a gun, a European American, and brands that date to the historic period.
In addition to historic items shown in rock art, depicted atlatls (throwing sticks used to propel stone-tipped darts) and bows and arrows are reliable time markers. The bow and arrow was first introduced onto the Columbia Plateau between two and three thousand years ago; before that, hunting weaponry was the spear or atlatl and dart. Atlatls are shown occasionally in rock art throughout the western United States. On the Columbia Plateau, probable atlatl depictions occur at petroglyph sites near The Dalles and on the Snake River south of Lewiston, Idaho. These panels were probably carved before the Indians acquired the bow and arrow. On the other hand, bows and arrows are relatively common, both as petroglyphs and pictographs, throughout the Columbia Plateau, occurring at sites in British Columbia, Washington, Oregon, and Idaho. These designs must date within the last two thousand years.
Superimpositions
Occasionally one design will be carved or painted over another; thus superimposed, the overlapping figure must have been made more recently than the original. A series of superimpositions, involving stylistically distinct examples, can be useful in developing a generalized chronology for a region’s rock art, since the relative ages of each style can be shown. In some areas of the world (e.g., Valcamonica, Italy; Dinwoody, Wyoming; Coso Range, California), frequent superimpositions characterize rock art, and relative chronologies have been developed from detailed analysis of many instances of superimpositioning.
In Columbia Plateau rock art superimpositions are rare, although they occur occasionally in some parts of the region, most frequently along the middle and lower Columbia River.