Petroglyph dating on the Massacre Bench

While many archaeologists show great interest in rock art, direct dating remains critical to the integration of rock art research into mainstream archaeology. When the production of rock art can be situated in time, it can be analyzed alongside other concurrent cultural practices and a more richly textured study of prehistoric human behavior developed. Only when rock art can be placed within its larger social context can it be reasonably understood as a part of the complex lifeways of indigenous peoples. This comprehension is, however, not necessarily the case in analyzing the use of rock art, since these sites appear in many cases to have been utilized over very long periods of time. Once a monument (like rock art) becomes a part of the landscape, it begins to influence later inhabitants, perhaps even drawing people to it (Bradley 1993:2, 5-6, 1997:11, 1998). These places probably accumulated meanings through time and came to be perceived as places where ancestors had left their mark (i.e., rock art), thereby becoming points of articulation between time and space through re-use (Basso 1996:62; Bradley 1993:53). In this way rock art may have been instrumental in the shaping of social relationships through reference to the past and the place as a part of the cultural landscape created by the ancestors for subsequent use by their descendants (Taçon 1994:118; Woody 2000a:231). Although the use-life of rock art extends beyond its actual production, and possibly even into the present, the importance of identifying its starting point is not diminished. Establishing the point in time at which rock art enters into, or begins to help shape, the cultural landscape, allows for clarifying the possible sequence of use and articulation with associated behaviors. Direct dating of rock art does not answer all-or arguably even the most important-questions, but it does provide a significant starting point for analysis. In the past, without reliable methods of direct dating, several approaches have been used in estimating the age of rock art. Identification of datable objects or animals in the imagery as a means of determining age of rock art is problematic at best (Bednarik 2001; Tuohy 1969), but it has proven useful in some cases (Grant, Baird, and Pringle 1968). Although traditional relative dating methods such as superposition, seriation, and analysis of differential patination can also be useful (Chippindale and Taçon 1998; Lee and Hyder 1990; Loendorf 1994), such methods are not without their critics (Bednarik 2002; Dorn 1998a:69-96; Whitley et al. 1984). Bettinger and Baumhoff (1982) used differences in petroglyph manufacture as one factor in hypothesizing the expansion of populations who spoke a Numic language into the Great Basin and thus dating "styles" of Great Basin rock art, although this approach has been contested (Ritter 1994). It remains difficult at best, however, to unambiguously relate rock art manufacture to other site activities without direct, reliable dating. Pictograph dating is generally well accepted, simply because the binders used to produce paint are often organic and so accelerator mass spectrometry radiocarbon (ams14c) and other traditional dating techniques work reliably and are widely used (Chaffee, Hyman, and Rowe 1993a, 1993b; Clottes 1998a; Watchman 1993b). Petroglyph varnish dating using cation-ratio techniques showed early promise (Dorn 1983; Dorn and Whitley 1984), but controversy arose (Bierman and Gillespie 1991; Bierman, Gillespie, and Kuehner 1991; Dorn 1994a, 1997; Harry 1995; Watchman 1992, 1993a) and the method has since been abandoned by its developer (Dorn 1996). However, some researchers continue to use it (Tratebas 1999), in an apparent effort to refine the technique. Methods of ams 14C dating of petroglyph varnish have also been developed (Dorn 1998b; Watchman 1999; Watchman et al. 1993), and in this chapter we present the results of one such study on petroglyphs on the Massacre Bench in northwestern Nevada. The limitations of varnish and other rock art dating techniques have been discussed by Bednarik (2002), but in general, limitations revolve around the great likelihood of contamination of samples, the fact that "dates" obtained are actually only broad ranges of time, and basic flaws in the assumptions upon which interpretations are made.