Toolstone Preferences

Diverse lithic material types are represented in the prehistoric flaked lithic assemblages from San Diego sites. Contrasts between the materials in different assemblages have been attributed to chronological changes in technology, mobility, or exchange systems, or to geographical differences in the most accessible local sources of toolstone. General discussions of issues relating to toolstone preferences have been offered by Andrew R. Pigniolo (1996, 2013) and John Dietler (2004).

Early investigators reported the existence of characteristic associations between archaeological complexes and particular lithic material types. Malcolm J. Rogers (1929:460-461) noted the use of both Santiago Peak volcanics and sedimentary volcanic cobbles in early San Dieguito assemblages. James R. Moriarty III (1966:21, 23) suggested that the use of cobbles from conglomerate lenses was one of the main criteria for defining La Jolla I (ca. 7500-5500 BP) components, and that the first appearance in quantity of quartzite, obsidian, felsite, and cryptocrystalline silica was during the Diegueño I phase (ca. 3000-400 BP). Claude N. Warren (1966:13-14) reported that San Dieguito tools at the C. W. Harris Site (SDI-149) were made primarily from locally available felsite and basalt, with occasional quartz and quartzite tools, but rarely cryptocrystalline silica. The subsequent La Jolla and Yuman assemblages included a higher proportion of cryptocrystalline silica, quartz, and quartzite.

Pigniolo (1996) argued against any exclusive associations between toolstone types and archaeological stages, periods, or complexes. He interpreted the associations that had been claimed by earlier researchers as reflecting differences in the locally available materials and changes in technological requirements, particularly nodule size. Santiago Peak volcanics were associated with the San Dieguito Complex, in this view, because large, quarried nodules were needed to produce the complex’s characteristic leaf-shaped bifaces, and also because assemblages that were dominated by Santiago Peak toolstone tended to be assumed to be San Dieguito. Early coastal assemblages made use primarily of the local, coarser-grained volcanic and quartzite cobbles, but they were not necessarily chronologically distinct from the inland San Dieguito assemblages. A Late Prehistoric technological shift to arrowpoints and other small tool types allowed for greater exploitation of toolstones that were available primariy in small nodules, such as quartz, cryptocrystalline silica, and obsidian, although it did not interfere with the continued use of Santiago Peak volcanics in locations where the latter were available.

Dietler (2004) looked at Late Prehistoric patterns of toolstone selection, using a sample of 62 residential sites within eight topographic/ethnic zones (Kumeyaay coastal, foothill, mountain, and desert zones; Luiseño coastal, foothill, and mountain zones; and Cupeño mountain zone). He distinguished seven general categories of toolstone in the analysis: volcanic, quartz, cryptocrystalline silica, quartzite, obsidian, Bedford Canyon metasediments, and other. Dietler concluded that Late Prehistoric toolstone selection was based on a combination of local availability and material preferences, with obsidian and cryptocrystalline silica being ranked higher than volcanic rock, and volcanic rock ranked above quartz and quartzite.

Pigniolo (2009) examined the limited geographical distribution of a metavolcanic toolstone of only moderate quality from the Lusardi Formation in the Poway area.

PROSPECTS

Future analyses of San Diego archaeological collections may be able to clarify the specific uses to which particular types of toolstone were put, the ways in which such use patterns changed through time, and the extent to which toolstone selection was affected by the distances separating the location where use occurred from the potentially competing geological source areas.