14 ALASKAN MINERAL RESOURCES IN 1904. [bull. 259. 
in this field the developments have not yet reached the stage which 
makes it possible to gather the detailed facts necessary for the exhaus- 
tive study of any given area. Of necessity much of the work has 
been of a preliminary character, but if this fact is specifically stated in 
the publication of results, intelligent mining men will not give undue 
weight to the conclusions presented. The attempt has been made to 
cover the whole mining field, as far as circumstances permitted, and 
to give the public the immediate benefit of the facts collected. 
Though it is self-evident that final statements concerning the mineral 
wealth of a region must be based on a comprehensive knowledge of 
the geology, it is equally true that many of the facts collected, and 
even the tentative conclusions reached while the study of the geology 
is being carried on, may be of very great value to the miner and pros- 
pector. If, however, the geologic work stops after the attainment of 
only such incomplete data and conclusions, its value is soon lost, for 
the knowledge obtained by the miner during the progress of develop- 
ments will soon be more complete and reliable than than of the geolo- 
gist. Reconnaissance investigations must therefore be supplemented 
b}^ detailed surveys, as fast as warranted by the mining developments. 
In Alaska the exploitation of ore bodies has not progressed far, and 
for the present in most of the mining districts general investigations 
would appear to best fulfill the purposes for which the appropriation is 
made. 
Much of the attention of the Survey in this field has been devoted 
to the gold placers, where the conditions of occurrence are so simple 
that even a hasty examination may lead to important conclusions. As 
an example, in 1899 a few weeks of field work near Nome indicated 
that the region had suffered a general uplift, and that very probably 
old seabeaches and high benches would be found which might con- 
tain workable placers. The probable location of such deposits was 
indicated before any excavation had been made in this type of deposits. 
Subsequent developments showed that these conclusions, though based 
on very incomplete data, were correct, for the ancient seabeach and 
high-bench placers near Nome have since yielded millions of dollars 
in gold. 
Much the larger part of this report will treat of the placer mines, 
because they are at present the largest wealth producers, and more 
attention has been given to their investigation by this division. An 
attempt has been made, however, to summarize the general develop- 
ments in mining for the year 1904, so far as data are available. If 
this volume meets with the approval of the mining public an annual 
bulletin will be issued. 
It is a matter of regret that the plan of prompt publication has 
made it necessary to limit the illustrations to a few outline maps 
The important reports here abstracted will, however, be published ii 
more complete form, with all necessary illustrations. 
