Unit JK data analysis

Unit JK was located on the level ground surface within the traveled way of the Lot 28 road but along its northern edge.  The Unit was designated after John Kelsey (Elem Tribal Elder who lived along the Lot 28 road).

The unit was oriented in a general east-west direction in line with the existing roadway. 

Unit JK was a 1X2 meter excavation conducted in arbitrary 10cm levels based on the surface contour.  Each 10cm of soil was dry screened through 1/4” mesh shaker screens.  All material not passing through the screen was bagged and returned to the lab for processing.  The unit was excavated to a depth of 40cm. 

Unit JK soils were cleanly layered. At the base of the unit (40cm) the floor was covered with fist-sized volcanic bombs suggesting a major volcanic event.  Lying atop these rocks was a 30cm thick cultural midden consisting of dark gray/brown soils containing an abundance of obsidian, shell, and charcoal.  Atop the cultural soil was a layer of light brown gravelly fill, most likely brought in as fill to stabilize the roadbed.  Atop this road fill was a layer of mine waste that had also been used to fill in wheel ruts and stabilize the roadbed.  The wheel ruts are easily seen in the east and west profile drawings.

A.    Light yellow/brown mine waste.

B.    Light brown gravelly fill soil.

C.    Dark gray/brown midden containing an abundance of shell, charcoal and obsidian.

Both the soil profiles and the excavation level records indicate that the mine waste layer did not extend below a depth of 10cm.

This photo of the 40cm floor of unit JK shows a layer of volcanic bombs.  It is likely that this layer covers much of the reservation and is the geologic marker of the most recent eruption within the Lake Basin.

The volcanic bomb pictured here is typical of those recovered from unit JK.

JK Unit Historic Disturbance (soil integrity)

Analysis of all material recovered indicates the range of cultural material represented in the unit.  The top graph shows all material by level, the middle graph shows all material minus chipped stone (debitage).

The bottom graph shows only “Euro American Other” material and indicates the depth to which historical soil mixing has occurred.

It is clear from the bottom graph that most recent historic material was recovered from the top 10cm of soil (5 times the weight of historic material recovered from any other level).  This indicates that soils within the top 10cm of the unit were historically mixed.  Although a small amount of historic material was recovered from all levels, it is likely that these materials were moved through the soil column by rodent action and do not indicate historical soil mixing.

This suggests that soils below a depth of 10cm at unit JK remained intact.

Chipped Stone

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.

Points (3)

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. (hydration rate calculation is based on Origer 2008 and Tremaine and Fredrickson 1988).

Knives (3)

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 level (JK-163). 

Flake Tools (44)

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 (JK-162).

Cores (9)

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).

Bone tools (2)

One polished bone awl tip was recovered from the 10-20cm level (JK-88).  Another piece of unidentifiable polished bone was recovered from the 20-30cm level (JK-128).  Awls, pins, and other polished bone items were used for a wide range of applications including basketry manufacture.

Dietary Bone and Shell

Very little dietary shell was discovered and all was confined to the 0-10cm level, indicating that it was from the historically disturbed soil layer. 

Dietary bone was found in all levels indicating that it represented part of the prehistoric diet.  Mammal bone dominated the collection by weight; however, significant amounts of fish and bird bone were also found.

The lighter weights of fish and bird bone are not an indication that these resources were less valuable than mammals in the diet.  Both fish and bird bone are much less dense and lighter than mammal bone supporting the same amount of edible flesh.  In addition, these lighter, less dense bones decompose more quickly in acid-rich soils.  Due to decomposition, it is likely that more fish and bird bone existed at the time of site use than was recovered during this project.

The 1/8” sample did not recover enough bone for any meaningful analysis.

Beads (1)

A single mission-period glass bead (JK-115) was recovered from the 20-30cm level.  The cane bead was of milk glass and 7mm in diameter.

Period of Use

This table lists all hydration readings that were obtained from unit JK material.  If the readings from the disturbed 0-10cm level are discarded along with Napa obsidian readings and second band readings (often considered not to represent the time of tool manufacture), then the hydration data provides a focused period of use for the upper 40cm of soil at this location.

The hydration readings from the 10-20cm level average 5.6 microns (3,000 B.P.).  Readings from the 20-30cm level average 4.8 microns (2,200 B.P.).  The 30-40cm readings average 5 microns (2,400 B.P.).   It is likely The hydration readings from the 10-20cm level average 5.6 microns (3,000 B.P.).  Readings from the 20-30cm level average 4.8 microns (2,200 B.P.).  The 30-40cm readings average 5 microns (2,400 B.P.).   It is likely that the cultural material recovered from unit JK was manufactured sometime between 2,200-3,000 B.P. 

Interpretation

At the unit JK location, the upper 10cm of soils had been historically disturbed.  With the exception of minor rodent disturbance, soils below 10cm were intact and contained a significant amount of cultural material.

The base of the unit (40cm) contained a layer of volcanic bombs and soil that likely represent the most recent eruption in the Lake Basin.  Although archaeological excavation stopped at a depth of 40cm, it is likely that beneath this volcanic layer, there would have been additional layers of cultural soil representing material left by people that lived at this location prior to that eruption.

The material recovered was left by a community that was living at this location between 2,200 and 3,000 B.P.   This corresponds with cultural component #2 as identified during the Storm Drain data recovery work (reported on another web page).  Tools and dietary remains suggest that this community depended on lake related resources such as waterfowl and fish.  In addition, hunting, butchering, and hide preparation tools suggest some dependence on terrestrial mammals. 

A bone awl tip suggests that basketry manufacture may have taken place. 

Chipped stone tool material suggests that only the final shaping and sharpening of stone tools was taking place at this location.  Core preparation and initial shaping were taking place away from this area.

The existence of a Napa obsidian point suggests that village territorial boundaries were well established by 3,000 B.P.  Through cross-boundary trade, exotic materials can travel great distances from village to village without the individual having to travel great distances to obtain them from their place of origin. 

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Last modified: April 26, 2011