x PREFACE. 
conflict with generally accepted theories. The only course for me to pursue was, 
to examine with care the evidence offered, and, if I could find no flaw in it, to make 
it public. I may be permitted, in this connection, to allude to the circumstance that 
nearly all those who refuse to accept my conclusions as to the great antiquity of man 
in California, do so on the ground that the Calaveras skull was not taken from its 
bed by the hand of a scientific man. In so doing, they not only ignore the evidence 
presented by the skull itself, which 1s positively a fossil, and was chiselled out of its 
gravelly matrix in the presence of several eminent authorities, but they also reject 
the very full testimony from other quarters, some of which comes from men of educa- 
tion, and even of professional education. The body of this other evidence is so great 
that it does not appear to me that it would be materially weakened by dropping that 
furnished by the Calaveras skull itself. 
At the time of beginning the present volume, it was my intention to include in it some 
account of the glacial phenomena and surface geology of the Pacific Coast, as being 
subjects closely connected with the occurrence of the gravels. After some further con- 
sideration, finding that a volume which should contain this additional matter would 
be inconveniently bulky, I thought it best to divide the work, and to issue the glacial 
and surface geology separately. This has been done, and the first part of the “ Climatic 
Changes of Later Geological Times: A Discussion based on Observations made in the 
Cordilleras of North America,” will appear at the same time with the concluding portion 
of the present work. The part first issued contains a pretty full account of the glacial 
phenomena of the region of the Cordilleras, and a brief recapitulation of those facts which 
prove, beyond possibility of doubt, that during the later geological periods a gradual 
desiccation of the earth’s surface has been going on, and, as there is good reason to 
believe, is still continuing. The concluding portion of the “Climatic Changes” will be 
issued during the coming winter: it will contain a discussion of the facts set forth 
in the preceding two chapters and in the gravel volume, showing a gradual diminution 
in the amount of precipitation, as having been begun during a previous geological 
epoch and as still continuing, while, in certain regions, large areas have been covered 
by ice where none now remains. The endeavor will be made to trace the connection 
of these facts, and to show that they are manifestations of one great general cause, which 
has been in operation during an indefinite period, and is likely to continue to operate in 
the future. 
J. D. WHITNEY. 
CAMBRIDGE, Mass., Oct. 1, 1880. 
