propriated for "geologic maps of the United States" has been nearly $2,500,000. To this there should be added a large part of the "lump-sum" appropriations made to the Survey during 1879-1888. It seems fair to conclude, therefore, that the geologic surveys proper, exclusive of surveys in Alaska, have cost nearly $9,000,000.

Investigation of Mineral Deposits. In addition to its surveys of selected areas, the Survey makes many investigations and surveys with a view to determining the occurrence and distribution of the deposits of a particular mineral, or the mineral deposits in a particular area. Much of this work that is done on the public lands is a direct incident to the task of classifying or evaluating those lands under the land laws, and this phase of the work will be discussed in a subsequent sec

tion.

The investigations here considered are thus concerned only with a single class of mineral deposits. Though the Survey's work in Alaska has from the beginning been conducted under appropriations for the "investigation of the mineral resources of Alaska," no specific phrase of that kind has ever been used in appropriation bills covering investigations in the United States, which have been conducted under the general authorization for "geologic surveys." Investigations of this type are generally undertaken by the Survey with reference to a deposit of major importance in a field not yet adequately exploited. The Survey attempts to outline the limits of the area in which occurrences of the deposit may be expected, and to indicate the zones in which the richest deposits are likely to be found and the general conditions to be expected. An investigation of this type is the Survey's work on the oil shales of the Green Bay region.

The Survey also, when an unusual demand arises for any mineral product, makes a general investigation of the occurrence of that mineral. Investigations have thus been made of such minerals as monazite, zircon, iridosmine, platinum,

and all minerals possessing radio-active and radio-responsive products. More recently a systematic search has been made for new deposits of petroleum, phosphates, nitrates, potash, pyrites, and manganese.

For the proper conduct of exploratory researches of this kind, and indeed for the most effective collection of data relative to mineral deposits in the course of general geologic surveys, it is essential that the geologists conducting the operations be thoroughly versed in the technology of the production of the mineral sought.

Recognizing that the ability to form a correct judgment as to the practical utilization and value of an ore or other mineral deposit in the ground is most effectively acquired through the field observation of operating works and processes for the exploitation and reduction of the same or similar deposits, the Survey regards it of the highest importance that the geologists who may be called upon to appraise undeveloped mineral resources in the public domain or in other regions of the country shall keep as closely as practicable in touch with the mineral industry, and shall have a knowledge of the factors conditioning the successful treatment and utilization of the ores he is examining.3

The methods employed in searching for new deposits are not unlike those followed by private prospectors possessed of adequate funds and acting under the advice of trained geologists. If possible, coöperative arrangements are made with private parties who may be drilling in the areas selected for exploration or in adjacent areas by which the cores removed by their drills are turned over to the Survey for examination and report. This method has been employed most consistently in connection with the search for potash deposits which the Survey has been making for several years. Describing this coöperation, the report of the Director for 1915 states: 4

3 Report of the Director of the Geological Survey, 1915, p. 47. 4 P. 44.

Every effort is made to cooperate with all drillers who may be boring in the regions which are under examination or which it is thought may contain large saline deposits. Sample bags and specially prepared log books are furnished to them with the request that cuttings be taken from every "screw,” at least in the regions of the formations containing or adjacent to the saline or gypseous deposits. Also samples of brines are solicited. All these samples are tested for potash in the laboratory of the Survey, and the drillers are informed as to whether potash is present in considerable amounts in any of the samples. In the lack of funds sufficient to carry on the exploration more rapidly and especially to conduct boring operations in several areas at once, the effort will be made, whenever possible, to station scientific observers at the sites of new drillings in areas which would appear to be especially promising or in which indications have been reported, in order that the cuttings of the drill may be watched on the ground by a competent observer and tests made of the samples and brines as the work progresses.

In addition to the explorations above described, the Geological Survey is testing all samples sent to it for examination from reported discoveries of potash salts or nitrates. It has also made field investigations of reported deposits concerning which the tests have been favorable, and the information submitted with the samples has warranted the hope that the deposits might prove to be of value.

Research in Geologic and Related Theory. In the Survey's researches for mineral deposits, as in all such researches made by trained geologists for private parties, the area of operations is selected and the operations themselves are guided by a hypothesis or theory relative to the occurrence of the mineral sought. It need hardly be added that the Survey, as the largest single organization engaged in such researches and in the collection of geologic data generally, is itself a prime factor in formulating and developing theories of mineral

Occurrence.

The Survey has from the first taken the position that a great and peculiar field of usefulness lies before it in this type of research.

The principles controlling mineral deposition and the laws governing the occurrence of ore bodies can be satisfactorily determined only as a result of the comprehensive study of many mines and mining camps. This work is beyond the reach of individuals but is appropriate to the national organization. The application of the principles to particular ore bodies and camps is quite within reach of the individual mining engineers charged with development work.5

In large measure geologic and mineralogic data that form a basis for researches of this type already exist in the results of the Survey's work. The search made for specific mineral deposits by the Survey also frequently contributes materials of considerable theoretic value.

The broad and searching observations which should accompany every piece of good economic work comprehend data that are eventually combined in the construction of new scientific hypotheses, some of which, as more observations accumulate, grow into established laws or principles that are in turn of the greatest practical consequence. Thus the detailed studies of the metalliferous deposits in one region or another bring to light evidence from which to determine the genesis of the ores and the modes or conditions of their occurrence.

Both these classes of existing data must, however, frequently be supplemented by special studies in the field and in the Survey's laboratories. As illustrative of the Survey's chemical and physical researches may be mentioned extensive laboratory investigations of the diffusion of gold and silver into lead and tin, the linear force of growing crystals, the migration of natural oil in certain sands, and the enrichment of ores of silver, copper, etc.

The Survey's investigations of certain problems of mineral occurrence border closely upon investigations made by the Bureau of Mines in the field of mineral utilization. The Sur

5 The United States Geological Survey: Its Origin, Development, Organization and Operations, 1904. Bulletin No. 227, p. 31 f. Report of the Director, 1912, p. 16.

vey, for example, has studied the causes of the entrance of water into oil-producing sands, which has occurred on a large scale in certain oil fields, especially in California, with the result that large quantities of oil can never be extracted, and the Bureau of Mines has studied methods of remedying the evil and engineering devices for conserving the oil. In these joint studies the field to be covered by each bureau is clearly outlined and the work is carried out in a spirit of coöperation.

In addition to the investigations designed to develop the theory of the occurrence of some particular mineral, the Survey continuously prosecutes studies and investigations designed to develop general geologic theory. The purpose held in view by the Survey in studies and investigations of this kind was thus clearly stated by Major Powell in his testimony before the joint congressional commission of 1885-86.7

There are many investigations that may not at first seem to lead to economic results, but which ultimately and indirectly are of importance even for economic purposes. The scientific man, especially the geologist, for reasons which I have heretofore set forth, has to do with a vast complexity of problems. To select a part of these problems and work upon them may not lead to substantial results when other problems are neglected that have relation to the first. The whole body of research in geology has a very important practical value, because geologic investigation reveals the wealth buried beneath the surface of the earth. Sound geologic conclusions cannot be reached by following a few narrow lines of investigation, but all such lines of research must be followed that each may shed light upon the other. Unless this principle is fully recognized, a geologic survey might lead to conclusions of no value to the people at large, or conclusions might be reached so erroneous as to be misleading. It therefore often happens that in determining to inaugurate investigations in a particular line the one question asked is, "Are we likely thereby to discover facts that will shed light upon the general

7 Testimony before Joint Commission, 1885-86, Senate Misc. Decs., 49th Congress, Ist Session, Vol. 4, p. 700.