These five specimens were localized in the southeast sector of the deposit, and none occurred deeper than the 12-to-18-inch level. Numerous Phase II projectile points came from this same general area of the site and therefore there is some inclination to assign these specimens to a late position in the Phase I with the probability that they are Phase II.
Abrading Stones
Two broad classes of abrading stones have been differentiated on the basis of form and inferred function (Treganza and Malamud 1950, p. 147):
I. Those that could be held in the hand and rubbed against some article being finished. These have smoothed, even-abrading surfaces that are gently concave to convex. They are clearly distinguishable from manos by their reduced average proportions, and the near consistent lack of pecking as a sharpening measure. That this latter characteristic does not hold without exception seems to be due simply to the fact that some of the abrading stones appear to be reused manos.
One of the examples in the above category, originally a broken bifaced mano, has small, half-inch deep depressions at either end. These evidently served as finger-holds, for they effect a good grip on the tool.
II. Those that, though quite varied in size, bear one or more grooves on their faces. The furrows vary in breadth and depth and appear to be a function, essentially, of the amount and kind of wear to which the artifact was subjected.
Many of these specimens, especially those with narrow, V-shaped longitudinal grooves, would be classed as awl sharpeners had they occurred in sites of later origin. However, bone awls or pointed, worked bone in any form is absent in the Tank Site. It would suggest, then, that this class of abrading stones were involved in conjunction with wood working, the tangible evidence having been lost to us.
Cog Stones
Cog stones, because of their unique forms and restricted distribution, may be useful as diagnostic elements for future comparative studies. As yet we know little about their function or cultural associations in the rest of southern California. Their temporal position appears to be a middle one, as none occur in positive association with late or historic sites, and conversely, none have been reported for Lake Mohave, coastal San Dieguito, or Oak Grove. The Tank Site specimens represent the earliest known occurrence, and even here their exact position as to Phase I or Phase II is not fully known. Most of our specimens occur in the top levels (0-18 inches), though a single example was found as deep as 32 inches (pl. 23, b).
We have suggested cog stones in southern California may constitute the counterpart of the spindle charm stones of central California with the south boundary of the Chumash marking the near southern limit of the spindle forms. Material out of which cog stones have been made is of some interest. The Tank Site specimens range through volcanic tuff, siliceous sinter, escoriated basalt, to a fine-grained basalt. From other areas the same materials are present plus sandstone, granite, and granodiorite. Steatite, one of the most easily worked stones, appears to be absent. Obviously the hardness and type of stone were of little importance. The appearance of the finished product likewise varied. Some specimens are a product of perfection, others of the roughest sort. Perforated specimens might suggest hafting, but few are of this type.
The suggestion of a ceremonial usage of cog stones is not solely lacking in evidence. In 1936-1937, under the Works Progress Administration, Mr. J. W. Winterbourne excavated two sites in Orange County known as the Banning Site and the Norris Site. The following are excerpts from a letter dated April 13, 1939, to Edwin F. Walker from J. W. Winterbourne (we are indebted to Mr. H. Eberhart for providing this data from his manuscript on cog stones):
“I am enclosing some data on cog stones that one of the clerks gathered from the field notes.... We have noticed several peculiarities regarding this cogged discoidal. First, that the Banning Estate Site seems to have produced as many of these stones as all the other sites where they are found combined; second, that the stones in most cases are found in the clay completely below the camp debris; third, that rarely have they been found in association with other artifacts except the discoidal; fourth, that they seem never to have served a utilitarian purpose as they are not pitted or polished and rarely broken; fifth, if broken, in almost every case the Indians attempted to mend them with asphalt; sixth, that the material used in their manufacture is with few exceptions a vesicular basalt which is found in outcrops in the San Joaquin Hills and at various points in the Santa Ana Mountains; seventh, that the number of cogs or depressions may vary three to twenty-five or thirty-eight, that the stone may be perforated near the center of the planes or it may not be, but that usually there is a depression near the center of both obverse and reverse planes.”