28 BUREAU OF AMERICAN ETHNOLOGY | puLn. 33 
Calaveras specimen must have great weight in favor of its cavern 
origin. A mass of gravel, bones, etc., adhered to the base of the skull 
when discovered, but this was not firmly solidified and could be 
removed without injury to the bone. It had very much the appear- 
ance of débris from some cave or crevice, cemented to the specimen 
while the latter was being coated with stalagmitic deposit. The infil- 
tration or fossilization of the Calaveras skull furnishes no reliable 
test of its antiquity. It will be shown later in this paper that even 
siliceous fossilization of bones can take place near the surface of the 
ground, and in all probability has taken place within a geologically 
insignificant period. The process is regulated wholly by the local 
mineralogical conditions and the results are of little or no value as 
chronological criteria. 
X.—THE ROCK BLUFF CRANIUM 
The specimen known as the Rock Bluff skull was reported on by 
Meigs,“ Schmidt,’ and Kollmann,’ and its claim to geological antiq- 
uity is based mainly on certain remarks found in Schmidt’s account. 
According to Meigs, the skull was found, with a lower jaw— 
. . in June, 1866, in a fissure of the rock, at Rock Bluff, on the Illinois river 
where it is crossed by the fortieth parallel. The fissure, which is 3 feet wide, 
was filled with the drift material of this region, consisting of clay, sand, and 
broken stone, the whole being covered with a stratum of surface soil. In this 
bed, which apparently had been undisturbed since the deposit, was found the 
skull under consideration, at the depth of 3 feet. 
After giving a description of the specimen, which contains several 
inaccuracies, Meigs speaks of a number of Indian cranta which show 
resemblances to that from Rock Bluff, and concludes as follows: 
Bearing in mind the locality in which it was found, the skull under considera- 
tion is so far unique in its ethnical character, that I do not feel authorized to 
refer it to any of the aboriginal American cranial forms with which I am 
acquainted. If the position in which it was discovered be any evidence of its 
age, it belongs, in all probability, to an earlier inhabitant of the American con- 
tinent than the present race of Indians. 
At the time of Doctor Meigs’s writing there was apparently extant 
no important evidence of the geological antiquity of the find, and had 
not the skull been of rather inferior type, it would hardly have 
attracted particular attention. Four years later, however, Schmidt 
gave a detailed description and measurements of the skull accom- 
panied by the statement that he was in possession of a letter from 
«J. Aitken Meigs, Description of a Human Skull in the Collection of the Smithsonian 
Institution, Smithsonian Report for 1867, 412-415, Washington, 1868. 
+E. Schmidt, Zur Udgeschichte Nordamerikas, Arch f. Anthrop., v, 237-244, 1871-72, 
¢ J. Kollmann, Hohes Alter der Menschenrassen, Zeitschr. f. Hthnol., xvi, 191-193, 
1884. 
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