PREFACE, 
Baron Ferdinand von Richthofen, by his extensive exploration and 
penetrating research, laid the foundation for all future geologic work in 
China. In his journeys from the extreme south to the far north, from 
the eastern plains to the western ranges of the Empire, he observed all 
phases of geographic and geologic phenomena presented in that vast area, 
and grasped the problems broadly and strongly. His early views, pub- 
lished in 1878 and 1882, were developed in accordance with theories which 
were unchallenged until the last decade of the century, yet as they now 
stand in ‘‘China”’ they do not always do justice to the advance which he 
made, keeping abreast of the science. With marked hospitality of mind 
he welcomed each new fact, received every new view that came fairly 
accredited, and even though he might not adopt, he courteously enter- 
tained them. The plans of the expedition of 1903-04 were laid before 
him at their inception and were perfected through his advice. After our 
return the results were discussed with him in Berlin during March, 1905. 
We are privileged to say that he looked forward with cordial interest to the 
publication of these volumes, in which his name so often appears, and 
in earnest search for the truth would have justly reviewed whatever they 
present of reliable fact or induction. In sincere appreciation of his great 
contribution to knowledge of Asia, we record our deep indebtedness to him. 
The plan of the Carnegie Expedition to China of 1903-04 was conceived 
by Dr. Charles D. Walcott, whose interest in geological science in general, 
and in the faunas of the Cambrian period in particular, had led him to 
a keen appreciation of the possibilities suggested by the results of Baron 
von Richthofen’s explorations. In accordance with Dr. Walcott’s purposes, 
the objects of the expedition were, from the first, purely scientific, yet 
comprehensive. It was intended that the scope of research should com- 
prise the stratigraphy and paleontology, the structure and physiography 
of the regions visited, and that the survey should be carried out with as 
much thoroughness as the local conditions might permit. 
The first grant for execution of Mr. Walcott’s purpose was made in the 
autumn of 1902, and Dr. Arthur C. Spencer of the U. S. Geological Sur- 
vey was charged with the preparation of plans, in the expectation that 
he would carry them out. Later, when Mr. Spencer was obliged to forego 
the opportunity, I volunteered for the service and the expedition was 
intrusted to me. Mr. Eliot Blackwelder of the University of Chicago was 
chosen as associate geologist, and Mr. R. Harvey Sargent of the U. S. 
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