b, lava; G, gravel; S, slate; R, old river-bed; R´, present river-bed. (Le Conte.)
It is evident that objects brought from a great depth below this lava cap must have remained there undisturbed since they were deposited along with the gravels, and that the evidence of the simplest miner, who says he brought them with a truck-load of dirt from the bottoms of shafts, or ends of tunnels pierced for hundreds of feet through the solid lava, is, if he speaks the truth, as good as if a scientist had found them in situ. And this evidence, together with that of mining inspectors and respectable residents who took an interest in scientific subjects, has been forthcoming in such a large number of instances as to preclude any supposition of mistake or fraud. Three of the latest of these discoveries were reported at the meeting of the Geological Society of America on the 30th December, 1890, and they seem to be supported by very first-class evidence.[14] Mr. Becker, one of the staff of the United States Geological Survey, to whom has been, committed the responsible work of reporting upon the gold-bearing gravels of California, exhibited to the Society a stone mortar, and some arrow or spear-heads, with the sworn statement from Mr. Neale, a well-known mining superintendent, that he took them with his own hands from undisturbed gravel in a mine of which he had charge under the lava of Table Mountain.
A second object exhibited was a pestle found by Mr. King, who was at one time General Director of the United States Geological Survey, and is an expert whose judgment on such matters should be final, and who had no doubt that the gravel in which he found the object must have lain in place ever since the lava came down and covered it. The third object was a mortar taken from the old gravel at the end of a tunnel driven diagonally 175 feet from the western edge of the basalt cliff, and 100 feet or more below the surface of the flat top of Table Mountain, as supported by evidence entirely satisfactory to Professor Wright, who had just visited the locality and cross-examined the principal witnesses. This may prepare us to consider the case of the celebrated Calaveras skull as by no means an isolated or exceptional one, but antecedently probable from the number of human implements found in the same gravels, under the same beds of basalt and lava, at Table Mountain and numerous other places.
Professor Wright in the article already referred to, which is the latest on the subject, and made after his visit to California in 1890, which he says enabled him to add some important evidence, sums up the facts as follows—
"In February 1866, Mr. Mattenson, a blacksmith living near Table Mountain, in the county Calaveras, employed his spare earnings in driving a tunnel under the portion of the Sierra lava flow known as Bald Hill. At a depth of 150 feet below the surface, of which 100 feet consisted of solid lava, and the last fifty of interstratified beds of lava, gravel, and volcanic tuffs, he came upon petrified wood, and an object which he at first took for the root of a tree, thickly encased in cemented gravel. But seeing what he took for one of the roots was a lower jaw, he took the mass to the surface, and gave it to Mr. Scribner, the agent of an express company, and still living in the neighbourhood, and highly respected. Mr. Scribner, on perceiving what it was, sent it to Dr. Jones, a medical gentleman of the highest reputation, now living at San Francisco, who gave it to Professor Whitney, who visited the spot, and after a careful inquiry was fully satisfied with the evidence. Soon afterwards Professor Whitney took the skull home with him to Cambridge, where, in conjunction with Dr. Wynam, he subjected it to a very careful investigation to see if the relic itself confirmed the story told by the discoverer, and this it did to such a degree that, to use Professor Wright's words, the circumstantial evidence alone places its genuineness beyond all reasonable question."
This is not a solitary instance, for the Professor reports as the result of his personal inquiries only a year ago in the district, that "the evidence that human implements and fragments of the human skeleton have been found in the stratum of gravel underneath the lava of Table Mountain seems to be abundantly sufficient;" among others a fragment of a skull which came up with a bucketful of dirt from 180 feet below the surface of Table Mountain at Tuolumne.
Dr. Wallace, in an article on the "Antiquity of Man in North America," in the Nineteenth Century of November 1887, thus enumerates some of the principal instances—
"In Tuolumne county from 1862 to 1865 stone mortars and platters were found in the auriferous gravel along with bones and teeth of mastodon 90 feet below the surface, and a stone muller was obtained in a tunnel driven under Table Mountain. In 1870 a stone mortar was found at a depth of 60 feet in gravel under clay and 'cement,' as the hard clay with vegetable remains (the old volcanic ash) is called by the miners. In Calaveras county from 1860 to 1869 many mortars and other stone implements were found in the gravels under lava beds, and in other auriferous gravels and clays at a depth of 150 feet. In Amador county stone mortars have been found in similar gravel at a depth of 40 feet. In Placer county stone platters and dishes have been found in auriferous gravels from 10 to 20 feet below the surface. In Nevada county stone mortars and ground discs have been found from 15 to 30 feet deep in the gravel. In Butte county similar mortars and pestles have been found in the lower gravel beneath lava beds and auriferous gravel; and many other similar finds have been recorded....
"Even these Californian remains do not exhaust the proofs of man's great antiquity in America, since we have the record of another discovery which indicates that he may, possibly, have existed at an even more remote epoch. Mr. E. L. Berthoud has described the finding of stone implements of a rude type in the Tertiary gravels of the Crow Creek, Colorado. Some shells were obtained from the same gravels, which were determined by Mr. T. A. Conrad to be species which are 'certainly not older than Older Pliocene, or possibly Miocene.'"
I do not dwell on the discoveries which have been made of human implements and skeletons in the cases of Minas Geraes in Brazil, and in the drift or loess of the pampas of Buenos Ayres, for although associated with extinct animals usually considered as Pliocene, there is a difference of opinion among competent geologists, whether the deposits are really Tertiary or only early Quaternary.