Fig. 12. × 1/2. Fragment of a stone used for grinding.

2. Flat Stones.

It is only from three small fragments that the presence of this type within the mound may be inferred. All three were recovered in stratum V; one of them, 1-8751, is shown in figure 12. Judging from the fragments, these grinding stones were square in shape, about 1-1/2 to 2 inches in thickness and were worn smooth, both on the horizontal surface and on the sides and ends. The occurrence of flat grindstones is not unprecedented in California; some have been found in Sonoma county[[68]] and elsewhere. They were perhaps used in the manufacture of shell ornaments and beads.

[68] Moorehead, l. c., p. 291.

3. Pestles.

Fig. 13. × 1/2. Pestle with depression on one side. Fig. 14. × 1/2. A grooved sinker. Fig. 15. × 1/2. Upper end of a pestle.

Many fragments having the usual form were found, but only one was perfect, and that of unusual shape. 1-8670, fig. 13, was recovered in cut A, 6 inches below the surface. It is 6-3/8 inches long, 3 inches wide, and 2-1/8 inches thick, tapering toward the pestle-like rounded end, the other end being flat. Marks on it show that it was also used as a hammer. Sunk into one of the sides, at about the center of gravity, is a long conical groove about one-third of an inch deep; the opposite side shows the beginning of another such groove. They may have been worn into the stone by using the broad side of the implement in driving stakes, etc. The beginning of a second groove, otherwise superfluous, on the opposite side seems to bear this out, as do the marks on the surface of the broad end. These latter indications are a proof that the utensil was not used as a pestle only. This is not the only instance of a pestle with side grooves. Ch. Rau pictures a very similar one from Tesuque in New Mexico.[[69]] Mr. Stevenson’s opinion that the side grooves served for holding the pigment which had just been ground by the pestle seems to be merely a conjecture on his part. A stone was found in the West Berkeley shellmound which seems arbitrarily to combine several purposes,—a groove encircling it shows its use as a sinker, a semispherical cavity which at its widest part breaks into the groove points to its use as a mortar.