Mammoth Rub Update - Society for California Archaeology

The excavations also revealed that the site served as a quarry
for stone tool material, and that it was probably utilized at
multiple times in prehistory. The topsoil (a dark brown
Rohnerville Loam from 0-90 cm) contains numerous
hammerstones, chert and obsidian debitage, and several
obsidian projectile points (Figure 3A, B). The projectile
points and obsidian hydration indicate a date of about
500CALYBP for the upper component (0-90 cm).
An additional component (or perhaps components) exists
from about 100-180 cm, a zone characterized by compacted
yellow loam subsoil. Hammerstones and debitage also occur
here, as do much larger (25-100 kg) detached blocks of the
jasper outcrop (Figure 2). The large blocks appear to have
been dislodged from the overhanging outcrop, perhaps to
facilitate quarrying activities. 3 I suspect that some of these
blocks were removed from the parent outcrop by way of
prying. Several backed bladelets of chert (Figure 3C, D, I)
and one of obsidian (Figure 3H) came from this component
as did an end scraper with apparent blade scars on its dorsal
surface (Figure 3C) and several small thumbnail scrapers.
The bladelets resemble those recovered from the lower two
components of the Duncans Landing Rockshelter (CA-SON-
Figure 2: Excavation at Jasper Rock. Photo by Breck Parkman, 2004.
348/H), an important archaeological site located 1.4 km south
of Jasper Rock (Schwaderer 1992). The Duncans Landing
Rockshelter contains at least five cultural components, the
next to the lowest (Component 2) dating to 9,000 CALYBP
(Component 1 has yet to be dated). 4 It is possible (but
certainly not proven) that the cultural component (or
components) found between 100-180 cm at Jasper Rock is
contemporaneous with the early Holocene occupations at
nearby Duncans Landing Rockshelter.
At Jasper Rock, additional cultural components may exist
from 180-350 cm. The single deep excavation unit revealed
quarry debris to 220 cm, and several possible hammerstone
spalls were found at 200-220 cm. The auger test made in the
same unit recovered what may prove to be small pieces of
quarry shatter to 340-350 cm. Additionally, two small bladelike
flakes of quartz were found at 200-210 and 310-320 cm,
but will likely prove to be percussive shatter or perhaps even
geofacts (Figure 3E, F). 5 Because the deep unit was sited
directly beneath a heavily-polished knob of the outcrop, care
must be taken to segregate possible geofacts and zoofacts
from artifacts. To this end, Glen Halverson, one of Tom
Origer’s students and my volunteer, created a mechanical
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SCA Newsletter 38(4)