207 
been that otherwise known as the historical deluge. Further, since it is 
impossible to suppose that the great submergence of the land of the Northern 
Hemisphere, to an extent known to have exceeded 4,000 feet, before the 
post-glacial age, nor that second submergence, which followed it, can 
have proceeded at the slow rate of modern changes of level, it seems 
necessary to admit an abrupt or paroxysmal character for these great 
changes of the relative levels of land and water in the later Tertiary 
time, and thus to modify very much the estimates of the absolute antiquity 
sometimes assigned to post-glacial, or Palaeocosmic man, who, as I have 
elsewhere argued, becomes, on the views above stated, the representative of 
the historical Antediluvians. 
The evidence adduced by Prof. Whitney and others for the Pliocene 
age of human remains found in the gold gravels of California, I have never 
held to be valid, and have regretted that able geologists should have com- 
mitted themselves to so startling and otherwise improbable conclusions on 
grounds apparently so insufficient. I have studied with care the facts de- 
tailed by Prof. Whitney in his recent memoir on the Auriferous Gravels of 
California, and have stated at length my objections to his conclusions in the 
appendix to my book, entitled “Fossil Men” (pp. 344 to 347). These 
objections may be summarised as follows : — (1) None of the specimens can 
certainly be affirmed to have been found in situ in the undisturbed 
gravel. (2) The fossil fauna and flora of the deposits consist, so far 
as known, of extinct species, with the exception of man and of a modern 
snail found in association with the Calaveras skull. (3) The human remains 
found belong to a somewhat advanced race of modern type. (4) The manner 
in which Prof. Whitney accounts for the deposition of the Calaveras skull on 
the supposition that it is contemporaneous with the gravel, is fanciful and 
improbable. (5) The so-called “ fossilised ” condition of the skull proves 
nothing. That it afforded on analysis 62 per cent, of calcium carbonate, 
merely shows that, after decay of the animal matter, its pores became infil- 
trated with that mineral, a change not requiring a long time. 
I have also much pleasure, in this connexion, in referring to the 
interesting paper recently communicated to the Academy of Natural 
Sciences, Philadelphia, by Mr. H. C. Lewis, of the Geological Survey of 
Pennsylvania, in which, for the first time, the age of the ‘ Trenton gravel,’ 
which has afforded the rude flint implements described by Dr. C. C. Abbott, 
is accurately determined. As Dr. Abbott’s discoveries have been extensively 
quoted, both in America and Europe, as evidence of pre-glacial or inter- 
glacial man, it is satisfactory now to be assured that the gravels in which 
these interesting relics occur are altogether post-glacial, and are really 
modern, fluviatile deposits. This age I had already assigned to them, in 
the appendix to “ Fossil Men,” on analogical grounds, but it has been fully 
proved by the observations of Mr. Lewis. 
The above remarks are necessarily condensed, and refer to conclusions 
which I have elsewhere supported at greater length, in publications, the 
