of any definite pattern from this, unless the decorative bands, which sometimes cover over the nodes in North Indian arrows, have been suggested by the trimming of the joints. In one South American arrow I observed lines running between the joints, blackened, which appeared to take rise from the peeling of the nodes. This is the only instance that has come under my notice, and the use of a hollow reed shaft is comparatively rare, and, when it does occur, the joints are often left rough and untrimmed. Explanation of Plate VII. A series of reed shafts of arrows from the Solomon Islands. The figures are numbered in the order of the stages of development of the pattern. On the OCCURRENCE of STONE MORTARS in the ANCIENT (PLIOCENE?) RIVER GRAVELS of BUTTE COUNTY, CALIFORNIA. By SYDNEY B. J. SKERTCHLY, F.G.S., M.A.I. [WITH PLATE VIII.] DURING a visit to the Spring Valley Gold Mine at Cherokee, Butte Co., California, my friend Mr. Louis Glass, the Superintendent of the mines, directed my attention to the discovery of stone mortars in the undisturbed gravel of the old river system of California. As this bears upon the question of the antiquity of man in North America the following notes may be interesting. I may add that being away from books references are unobtainable, but I believe Mr. Bowman has examined some of the finds and is satisfied that the mortars occur in situ. I am bringing one home with me.1 1. Geological Position. The Spring Valley Mines are situated on the Foot Hills of the Sierra Nevada, in one of the valleys of the Sacramento River system, which are here excavated to a depth of over 2,000 feet. The following is a section in the deepest part of the channel: 3. Blue gravel, full of decomposed meta- 5. Bed rock, metamorphosed cretaceous slates. 2 to 15 feet. 50 The mortars, of which about 300 have been found since the year 1849, occur in the white sand or gravel No. 2, and one, examined by Mr. Bowman, is said to have occurred in No. 3. The general relation of the beds is shown in the section in Plate VIII. The beds 2 to 4 constitute part of one of the old rivers which drained the country prior to the establishment of the present river system. This particular "Cherokee River" cuts across the valley of the Feather River, as shown in the section, and has been proved beneath the Sacramento River at the place marked "well." The gravel is for the most part well water-worn, even the large boulders, some of which weigh eight tons, being rounded, with the exception of those in bed 4, which are only sub-angular. I could detect no trace of ice action, and the whole deposit bears evidence of its fluviatile origin. The pebbles and boulders are "shingled," or lie pointing down stream. At the top of bed No. 3 impressions of leaves are sometimes obtained in a sandy loam very full of black vegetable matter. These have been examined by Prof. L. F. Ward and very doubtfully referred to Cinnamomum or Paliurus, but he remarks, "The specimen may possibly represent a Populus unlike any modern form." ""1 The blue (and more highly auriferous) gravels are sharply distinguished from the overlying white beds, there being often a "pan" of cemented gravel between the two, the cement being red iron oxide. The general opinion is that these blue gravels are of distinct age, and much older than the white. This seems borne out by the characters of the two deposits. The blue gravels contain many very large boulders of metamorphic and eruptive rocks with much black sand (ilmenite), while the white gravels are entirely free from boulders and contain but little black sand. 2. Age of the Gravels. Prof. Whitney considers the white gravels to be of Upper Pliocene age, and that with the blue gravels these auriferous 2 1 Diller, "Notes on the Geology of Northern California," "Bull. U.S. Geol. Surv.," 1866, page 16. 2 Geol. Surv. Cal.," vol. i, page 211. 1 deposits may represent the whole of the Tertiary. Dr C. A. White, quoted by Mr. Diller, suspects the whole to be of Upper Pliocene age; and Mr. Diller remarks that "all that can be definitely stated at present concerning the strata containing the leaf impressions is that they are more recent than strata known to belong to the Chico group, and that their flora, as far as Prof. Ward can judge from the few imperfect specimens at hand, has a pre-Pliocene aspect.' These conclusions are based upon the determination of the age of the lava flow which overlies the gravels, and from the age of the faults in the neighbouring Sierras. The lava flows are derived from the vicinity of Lassen's Peak (60 miles north of Cherokee) and are certainly not older than the close of the Pliocene; and as these lavas are faulted the dislocations are probably post-Tertiary. Part of the upheaval of this portion of the Sierras is thus of very recent geological date, and it is quite possible that the ancient river beds may have partaken somewhat in these movements, for I find from observations on the transporting power of the sluices at Cherokee that the present grade of the old channel (about 6 per cent.) could be much reduced and still afford sufficient transporting power to move the larger boulders in the blue gravels. Whatever be the absolute age of these gravels from a geological standpoint, their immense antiquity historically is beyond question. The present great river system of the Sacramento, Joaquin, and other rivers has been established; cañons 2,000 feet deep have been carved through lava, gravels, and into the bed rock; and the gravels, once the bed of a large river,3 now cap hills 6,000 feet high. There is ample ground for the belief that these gravels are of Pliocene age, but the presence of objects of human fabrication invests the gravels with a higher interest to the anthropologist than even to the geologist, and may suggest new views. 3. Occurrence of the Mortars. The working face of the mine is an artificial cliff of from 400 to 600 feet in height, the whole of which is fetched down by the water jets of hydraulic giants. The material is washed into the sluices and the mortars are found with the rest of the mass. They are thus not quarried out by hand, but fairly washed out from the gravel. They cannot have come from the surface, for none are ever found there, and many of them have 1 "Auriferous Gravels," page 283. 2 Op. cit., page 16. 3 The channel of the white gravels at Cherokee is 1,500 feet. |