VULTURE

WESTERN ARIZONA

Sections 1,12 R8W, T5N; Sections 4,5,6,7,8, R7W, T5N USGS Aguila 15' Quad; and Sections 2,3,4,9,10,11,14,15,16, R7W, T5N USGS Vulture Mountains 15' Quad, northwest Maricopa County, Arizona. Previous to this study, the Vulture source was the only fully documented archaeological obsidian source in central Arizona (P. Brown 1982). The geology here is very similar to other mid-Tertiary sources in the region, especially Sauceda. A series of bedded ash-flow tuffs are punctuated with roughly circular rhyolite bodies and remnant domes that grade to perlite or vitrophyre toward the outer margins (P. Brown 1982:230). Surrounding the silicic volcanics is an alluvium that contains chunks of rhyolite and basalt as well as marekenites up to 10 cm in diameter. The nodules are found at least 20 km south and east into the Hassayampa Plain and perhaps into the Gila River system. Nodule densities near the perlite-vitrophyre are fairly low (<10 per 5m²), but the area is a known "Apache Tear" locality for local rockhounds.

The nodules exhibit velvet-like to water eroded thin black cortex. The aphyric glass ranges from a nearly opaque brown-green to nearly transparent. Some nodules are banded or cloudy, and one specimen was evenly banded with greenish and black bands. The nodules are an excellent medium for small biface production.

Much of this source falls within a large lithic (obsidian, rhyolite, chalcedony) procurement site AZ T:5:5(ASU) (Brown and Stone 1982). Here, as at all the marekenite sources, sporadic occurrences of bipolar reduction stations are common. The presence of cores and debitage is also sporadic, probably corresponding to the prehistoric location of nodules. Small areas, usually less than 1m², exhibit 15 to 20 rejected flakes, angular debris, and bipolar core fragments. These bipolar reduction areas may be 5 to 50 meters apart. Brown and Stone's study indicated that only 10% of the artifacts were utilized (1982:82). The vast majority of the recovered materials were unused flakes (Brown and Stone 1982:82). This suggests that the nodules were 'test knapped' and those found suitable were removed. This pattern of bipolar test knapping and removal of desirable flakes and cores is common on all the middle to late Tertiary marekenite sources. The lack of utilized artifacts is also a common pattern. The main published work on this source is P. Brown's (1982) study, as well as Wilson et al. (1957).

Raw elemental concentrations for Vulture source standards. All measurements in parts per million (ppm).

This page maintained by Steve Shackley (shackley@berkeley.edu).
Copyright © 2001 M. Steven Shackley. All rights reserved.
Revised: 20 April 2004

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