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|Elem JK1 Excavation Unit Chipped Stone
|History and Prehistory of Lake County
In unit JK, 3 types of rock were being used for chipped stone tools;
Franciscan chert, basalt, and Borax Lake obsidian. Borax Lake
obsidian made up the majority of stone tool material recovered
throughout the reservation.
The flake technology graph indicates that the types of chipped stone
recovered represent mostly one phase of the stone tool
manufacturing process (secondary thinning). There were very few
flakes that could be categorized as core reduction flakes or primary
thinning and shaping flakes. This suggests that core reduction and
primary shaping of stone tools occurred at another location.
The chipping technology graph indicates an even split between the
numbers of pressure flakes and percussion flakes. Pressure flakes
are those flakes that are produced during the final edge-sharpening
phase of the tool making process. These are also the flakes created by
tool maintenance where resharpening and minor shaping take place.
Percussion flakes occur during the whole tool manufacturing process.
This suggests that most of the tool making process was taking place
elsewhere and that finished, or partly finished tools were brought to
this location where they were finished, sharpened, and maintained.
Fragments of two Borax Lake obsidian points and one Napa Valley
obsidian point (JK-109) were recovered from unit JK. The broken tip
(or tine JK-61) was recovered from the 0-10cm level and should be
considered part of the disturbed soil layer. The other two were
recovered from the 10-20cm level and were most likely close to their
original place of deposition.
JK-109 had a mean hydration reading of 6.5 microns suggesting
manufacture around 6,500 B.P. JK-110 had a mean hydration reading
of 5 microns suggesting manufacture around 2,400 B.P. (rate
calculation is based on Origer 2008 and Tremaine and Fredrickson
Knives are purposefully manufactured tools that have been chipped on both sides to
create a cutting or scraping edge. Some chipped stone knives are well-formed,
presumably taking much thought and time in manufacture. Others are less
well-formed and appear to have been quickly manufactured for one or more uses.
Knives can be used for a wide range of cutting and scraping activities such as those
needed for butchering and hide production.
One knife was recovered from the 10-20cm level (JK-107) and 2 from the 30-40cm
Flake tools are sharp flakes of obsidian that were casually picked up
and used for cutting, scraping, or reaming purposes. These tools
either show chipped edges from use, or have been purposefully
removed from a core to provide a sharp cutting edge.
Flake blades are long thin flakes that have been removed from
specially prepared cores. The core preparation and removal process
allows the creation of long thin flakes with two very sharp parallel
cutting edges. Ten flake blades were recovered; 2 from the 0-10cm
level, 6 from the 10-20cm level, and 2 from the 20-30cm level.
Flake gravers are small flakes with a very defined short cutting edge
opposite a flat face that allows the force of a finger to be applied to
assist in the cutting action. Two flake gravers were recovered from
the 10-20cm level.
Spoke shaves are flake tools that have been used to scrape a shaft
(such as a branch or basketry root). The action of scraping a shaft
creates an indented (concave) flaked surface. One spoke-shave was
recovered from the 0-10cm level (JK-60).
Flake knives are casual flakes that have been chipped on both sides to
create a cutting edge. One flake knife was recovered from the
10-20cm level (JK-108).
Flake scrapers are the most numerous and most casual of the flake
tools and show little or no resharpening. They can be any shape and
size and display edge chipping that indicates repeated use for
generalized cutting or scraping. Thirty flake scrapers were recovered
from unit JK; 1 from the 0-10cm level, 12 from the 10-20cm level, 7
from the 20-30cm level (JK-32), and 10 from the 30-40cm level
No cores were recovered from the 0-10cm level, 1 was recovered from the 10-20cm
level, 5 from the 20-30cm level (see JK-137) (one of which was of Konocti obsidian),
and 3 from the 30-40cm level (JK-161).