Blade Industry
A blade, microblade, or linear flake is generally defined as a lithic flake whose proximal-to-distal length is at least twice as large as its maximum width. The purposeful manufacture and use of such blades represented an important lithic industry prehistorically in such diverse regions as Mesoamerica, Arctic America, and the Near East. Evidence for a blade technology in San Diego County would have possible implications concerning the extent to which craft specialization — otherwise generally not apparent — may have been practiced in this region.
Within southern California, a strong case has been made for the existence of a blade industry in the Santa Barbara Channel area (e.g., Arnold 1984, 1987a, 1987b). Martin D. Rosen (1985) argued for the existence of intentional blade production as a part of biface manufacturing at IMP-3675, a Late Prehistoric site in western Imperial County.
The presence of a Late Prehistoric blade industry in western San Diego County was suggested by Dennis O’Neil (1982, 1984), based on evidence from site SDM-W-1556 in San Marcos. Materials recovered at that site included 11 unifacially worked blades, 42 utilized blades, 108 waste blades, and seven blade cores. A nine-type debitage classification that was extensively used in San Diego County (e.g., Cardenas and Van Wormer 1984; Corum and White 1986; Dominici 1985; Gross and Robbins-Wade 1989; Hector 1984; Rosen 1984) also distinguished blades as one of its types. This suggests the view that blades were a culturally meaningful category locally, either as an intentional end product or as a diagnostic byproduct.
Doubts have been raised as to whether the blade flakes in western San Diego County represent a specialized industry or merely random variation within a generalized flaking industry. D. L. True (1966:131) defined “Type 3 Used Flakes” as “long slender flakes with a length that is more than twice the flake width. These are true blades, although it is considered unlikely that their manufacture, as such, was deliberate. No developed blade industry is suggested for this area.” A study of several sites in the Spring Valley area by Don Laylander (1991) for the most part supported the conclusion that the blade flakes found in western San Diego County merely represent random variation within a generalized, casual, core-and-flake industry.
A complication in the blade issue is that two or three distinct varieties of blade industries, each with different end products and different manufacturing methods, might be hypothesized for the region.
What might be termed a “Type 1” blade industry, typified by the obsidian blade industry in Mesoamerica (cf. Crabtree 1982), produced thin blades with sharp cutting edges in a manner that economized the lithic raw material. Characteristic byproducts of a Type 1 industry include spent prismatic cores (cores with a prepared platform and with flake scars occurring systematically around that platform) and crested blades (preparatory blades with a longitudinal dorsal ridge prepared by prior systematic flaking perpendicular to the ridge). This is the variety of blade industry that was proposed for San Diego County by O’Neil.
A “Type 2” blade industry is that reported by Arnold for Santa Cruz Island, in which thick, columnar blades were removed opportunistically from amorphous cores and served as drill blanks, for use in shell bead manufacturing. In one variant, “Type 2a,” characteristic of the quarry area (SCRI-93), crested blades were not produced, but a high percentage of the blades were trapezoidal in cross section, and the number of blades removed per core averaged 1.6. In the other variant, “Type 2b,” characteristic of the China Harbor site (SCRI-306), the majority of the end-product blades were crested blades, and an average of 2.82 blades were removed per core.
PROSPECTS
Future archaeological investigations may be able to determine whether blade flakes represented a distinct industry in prehistoric San Diego, or whether they were essentially chance products of a more general flake industry. Evidence relevant to this issue will include the frequency of morphological blades within general flake assemablages, the extent to which the other characteristics of blades differed from those of the general flake population, the relative frequency of shaping or use damage on blade edges, the frequency of exhausted or discarded cores with multiple blade scars, the frequency of crested blades, and chronological or geographical patterning in the occurrence of blades.