GEOLOGY AND PALEONTOLOGY. 31 
appropriate to the national organization. The application of the prin- 
ciples to particular ore bodies and camps is quite within reach of the 
individual mining engineers charged with development work. 
That the Survey work does actually result in the development of 
these principles is evidenced by the simultaneous formulation by 
Emmons, Van Hise, and Weed of the doctrine of the secondary enrich- 
ment of metallic sulphides; b} r Emmons's statement of lateral segrega- 
tion as applied to the genesis of the Leadville ores; by Van Hise's 
development of the principles of metamorphism in relation to ore 
bodies, and by many similar results. 
The importance of aiding in the actual development of the resources 
of the country is constantly recognized, in two ways — first, by prepar- 
ing handbooks and summaries of existing information regarding par- 
ticular deposits or resources; second, by making careful structural 
studies of particular mining camps. Work of the first sort is exem- 
plified in the series of papers, together presenting a succinct review 
of the coal resources of the United States, published in Part III of 
the Twenty-second Annual Report of the Survey; another such paper 
is that grouping all existing data regarding the asphalt deposits of this 
country, published in Part I of the same annual report. Similar papers 
covering the clay resources, Portland-cement materials, gypsum, etc., 
are in preparation. Studies of individual mining camps are constantly 
being made, a large number of the areas having already been surveyed 
either provisionally or finally. 
In the early months of the development of a camp there are rarely 
sufficient exposures, either natural or artificial, to furnish data for 
a complete account of the ore bodies. Often at that time it is pos- 
sible only to formulate general statements as to genesis and structure. 
Occasionally it happens that even after detailed studies have been 
made development is pushed so rapidly that still further details become 
available. Cripple Creek, which was the subject of a very careful 
study in 1894, is now being restudied in order to take advantage of 
the development of the district since that time; Leadville, also, which 
was the subject of an elaborate monograph in 1886, is being restudied, 
and probably other camps of the W T est will, in time, warrant similar 
resurveys. 
For published results of the work of this division see the list of 
Survey publications, especially series a, b, c, d of the classification 
table. 
DIVISION OF ALASKAN MINERAL RESOURCES. 
HISTORY OF INVESTIGATIONS. 
In 1895, through an appropriation by Congress of $5,000 for the 
investigation of the gold and coal deposits of Alaska, the Geological 
Survey for the first time was enabled to take up work in Alaska inde- 
pendent of other organizations. The same amount was appropriated 
