Elem Knives Long Thin Knives (28)[1,100/1,800/3,900/6,900/7,400 B.P.]The most numerous of knives were the long thin knives. Most of these were of Borax Lake obsidian (25) although some were of Konocti obsidian (3). Specimens 0-31 and 0-73 had hydration rims of 4.3 microns indicating manufacture ~1,800 B.P. Item 0-293 had two rims suggesting the reuse of an existing tool. The oldest rim was 8.8 microns (~7,400 B.P.) and the more recent 6.4 microns (3,900 B.P.). Item 0-27 and 0-350 (not pictured) had readings of 3.5 and 8.5 microns indicating ages of 1,200 and 6,900 B.P. The constricted end of 0-73 may indicate use as a reamer.Broad Knives (27)[1,200/2,300/2,600/3,400/3,900/5,600 B.P.]Thin and broad, all but one of these knives were of Borax Lake obsidian. One was of basalt. Item 0-10 had a hydration mean of 7.7 microns indicating manufacture ~5,600 B.P. Item 0-42 had a 6 micron reading indicating manufacture ~3,400 B.P. Item 0-143 had two hydration bands; one of 6.4 microns suggesting manufacture ~3,900 B.P. and one of 5 microns suggesting reuse ~2,300 B.P. Item 0-150 had a mean of 3.6 microns indicating manufacture ~1,200 B.P. Item 0-152 had a mean of 5.2 indicating manufacture ~2,600 B.P. Item 0-66 (not pictured) had a reading of 5.2 suggesting manufacture ~2,600 B.P.Thick Irregular Knives (19) [900/1,100/1,600 B.P.]These knives appeared to be very roughly chipped and may have been “pre-forms” rather than functional knives. A pre-form is a piece of obsidian partially trimmed and shaped for transport. Once it reaches its destination, the final shaping, thinning and sharpening work is completed. Borax Lake obsidian had been used for 14 of these tools, basalt for 3, Konocti obsidian for 1 and obsalt for 1. Thosepictured here had hydration of 3.5 microns (0-12) indicating 1,100 B.P. manufacture and 3.2 microns (0- 161) indicating 900 B.P. Item 0-332 (not pictured) had a reading of 4.1 indicating an age of 1,600 B.P.Keeled Knives (6) [95/6,700/7,900/10,500 B.P.]Keeled knives were roughly triangular in cross-section, resembling a ship’s keel. Their use is unknown, however the three distinct cutting edges may have been important for drilling or reaming. White (1984:228) lists them as “expended” or used knives. Five of these knives were of Borax Lake obsidian and 2 were of basalt. Item 0-126 had a reading of 1 micron (95 B.P.). Item 0-371 had a reading of 8.4 microns (6,700 B.P.). Item 0-354 had a rim of 9.1 microns, indicating manufacture ~7,900 B. P. Item 0-347 had a reading of 10.5 microns (10,500 B. P.). KnivesKnives were chipped on both sides and had dulled (used) cutting edges. These items were divided into 5 main categories based on physical attributes. The primary difference between a knife and a point was the freshness or sharpness of the cutting edge. It was assumed that knife-edges would have been used repeatedly for a cutting, scraping, or sawing activity. This activity would have dulled the cutting edge. The sharp edge of a point would not have been used for cutting or scraping in an effort to maintain its sharpness for a hunting event. There were 109 knives recovered during project monitoring.All obsidian chipped stone tools that appeared to have diagnostic shapes were submitted for hydration analysis. Hydration readings were converted to approximate years B.P. (Before Present) using Thomas Origer’s (1993) rate for Napa obsidian and the Borax Lake/Napa obsidian conversion factor developed by Kim Tremaine and Dave Fredrickson (1988). Chipped stone knives can serve a wide range of functions, however, they are most widely noted for their use in butchering and hide preparation. It is important to note that not all animals that require butchering and hide preparation are obtained through hunting with spear, dart, or bow. It takes much less energy and is far easier to trap and snare most small mammals. Therefore, butchering tools can be found in sites where there is no evidence of hunting.Four major styles of stone knives were recovered during the monitoring program. An examination of the hydration readings for these items indicates that these styles were not all popular during the same time period.Thick Irregular KnivesThe thick irregular knives appear to have been manufactured between 1,000 and 1,500 B.P. (4-5 microns). Though their function is unknown, it is possible that these items were not knives, but rather rough “preforms” obtained from and shaped at the Borax Lake obsidian flow. Such preforms may have been used as items of exchange in the regional trade system.Broad Flat KnivesThe broad and flat knives were manufactured primarily between 2,000 and 4,000 B.P. (5-6 microns). A similar increase in the number of points was also found during this period.Keeled KnivesThough their use is unknown, these knives with a triangular cross section appear to be most popular prior to 7,000 B.P. (9+ microns).Long Thin KnivesThough there might have been a slight increase in their use at 7,000 and 4,000 B.P. (9 and 5 microns), these knives appeared to be in use through all time periods.