hydrography in an investigation of the underground waters of the State, the results of which will be published in the series of watersupply papers.

GEOLOGIC WORK IN MISSISSIPPI VALLEY.

During the year the areal and economic survey of the Eureka Springs quadrangle, in Arkansas, was completed and considerable progress made in the preparation of the folio. The manuscript for the Winslow folio, previously surveyed, was also completed and submitted for publication.

Progress was made in the general study of the lead and zinc deposits of the Mississippi Valley. A detailed report on the deposits of the upper Mississippi Valley was prepared and submitted for publication, and other reports are in preparation. In connection with this study special paleontologic investigations were made for the purpose of elucidating stratigraphic problems which have a direct bearing upon the distribution of these metals.

A detailed paleobotanical microscopic examination was made of samples of the oil shales which are associated with the lead and zinc deposits of southwestern Wisconsin, for the purpose of determining the causes of the localization of the hydrocarbons that seem to have influenced the distribution of the ores. As this investigation seems likely to offer a satisfactory explanation of the origin of the oil and gas in the older Paleozoic rocks, plans have been made to continue it and extend it to some of the areas of Ordovician and Silurian oil

and gas.

In April a general reconnaissance of the Carboniferous coal field of Arkansas was undertaken and is still in progress.

Brief reports on the glass sand of the middle Mississippi basin and on the clays of Garland County, Ark., were prepared for the annual economic bulletin.

GEOLOGIC WORK IN ROCKY MOUNTAIN AND PACIFIC STATES.

In the Rocky Mountain and Pacific States-a region that presents complex geologic problems and is rich in metalliferous and other economic resources-many surveys and investigations were carried on. These group themselves into the following classes: Areal and stratigraphic studies; glacial and physiographic studies; investigations of gold, silver, lead, and copper deposits; fuels; iron ores; miscellaneous economic deposits.

Areal and stratigraphic studies.-The Santa Cruz (California) geologic folio and a bulletin on the geology of the Taylorsville (Cal.) region were completed and submitted for publication The mapping of the Corona quadrangle, in southern California, was also completed.

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The Corona is the first of a series of quadrangles, comprising the Hesperia, Deep Creek, San Bernardino, Redlands, and one (unnamed) which includes the south end of the Tehachapi Mountains at the point of their junction with the Coast Ranges, which have been selected for early mapping, because it is believed they will furnish the key to the general geology of this section of the State. A geologic reconnaissance from the southern borders of the San Joaquin Valley in California northward to the south line of Merced County resulted in the preparation of a report designed to be published as a bulletin of the Survey, but it is probable that the report will not be published until the additional work necessary to complete the reconnaissance of the valley north of Suisun Bay has been done.

In Colorado about half of the Lake City quadrangle was surveyed in detail, some preliminary work was done in the neighboring San Cristobal quadrangle, and a reconnaissance was made of the Uncompahgre plateau for the purpose of elucidating certain stratigraphic problems. Special studies included one on the stratigraphy of the Cretaceous rocks of the Routt County coal field and another on the Morrison formation and overlying strata near Canyon, the latter being a continuation of a study of the same beds in New Mexico and southern Colorado which was made earlier in the season.

In connection with the completion of the detailed survey of the Coeur d'Alene mining district, which was begun the preceding field season, a stratigraphic reconnaissance was made in northern Idaho and northwestern Montana, the general results of which are incorporated in the economic report on the Coeur d'Alene district, which is nearly ready for publication.

Progress was made in the study of the marine Tertiary fauna of the Pacific coast, which has been of fundamental importance in determining the petroleum horizons of that region. As a result of the field work in this connection several geologic reconnaissance maps were prepared of areas studied, chiefly within the counties of Fresno, Kern, King, and San Luis Obispo, in California.

Glacial and physiographic studies.-Special glacial and physiographic work in this region included the completion of the report on the glaciation of the Uinta Mountains, Utah, which was submitted for publication, and the preparation of a bulletin on the landslides and rock streams of the San Juan region, Colorado, which is nearly ready for publication. Considerable progress was also made in the determination of the maximum glaciation of the Sierra Nevada, a problem of great scientific interest; but much additional field work will be necessary before a satisfactory report can be prepared.

Investigations of gold, silver, lead, and copper deposits. The revival of mining activity in Nevada and the recent development of several new and important districts in the southwestern part of the State have

created a great demand for information concerning the geology of this region. This has been met by a geologic reconnaissance of about 8,500 square miles of southwestern Nevada and eastern California. The area surveyed has been designated the Amargosa region, and includes the Goldfield, Bullfrog, Tokop, Silverbow, Kawich, Lida, and other mining districts, as well as a large part of Death Valley. A general report on the geology of this region has been practically completed. The Goldfield and Bullfrog districts were mapped and studied in detail, and complete geologic reports are in preparation. A preliminary outline of these investigations, with notes on the Manhattan, Searchlight, Eldorado, and other mining districts in the southwestern part of the State, is now ready for publication.

Other investigations of the precious metals, lead, and copper of the West include a report on the ore deposits, chiefly gold, of the Silver Peak quadrangle, Nevada, which was completed and is now in the hands of the Public Printer; a detailed report on the geology and ore deposits, principally lead and silver, of the Cœur d'Alene mining district, in Idaho, which was carried nearly to completion; a detailed report on the copper deposits of the Butte, Mont., district, which is nearly completed and will be submitted for publication before the close of the present calendar year; a detailed report on the Park City mining district, Utah, including a reconnaissance report on the neighboring Cottonwood mining region, which was carried nearly to completion and will be finished before the end of the year; a brief study of the copper deposits of the Sierra Nacimiento and the neighboring Zuni Mountains, the results of which have been embodied in brief reports that will appear as chapters in the general report on the mineral deposits of New Mexico; a short study of the placer gold deposits near Hahns Peak, Colorado, which resulted in the preparation of a contour map, covering about 25 square miles, and a brief report, published in the annual economic bulletin; and the completion of the special geologic map of the "Downtown district" of the Leadville region, Colorado.

In addition to the foregoing the annual economic bulletin contains a number of short papers on the precious metal and copper resources of other localities in the Western States.

A special study was also made to determine the horizon of the supposed Jurassic rocks of the northern Sierra Nevada, in which are contained the extensive metalliferous deposits of that region. This investigation, however, was not completed, and another season of field work will be necessary before the results can be prepared for publication.

Fuels.--In response to the demand for information regarding the fuel resources of the country a number of reconnaissance surveys were made of the coal fields of the West, notably the following: An area

of approximately 2,250 square miles in southwestern Wyoming, surveyed with special reference to coal and oil; an area of about 1,200 square miles, comprizing the coal lands in the valley of Yampa River, in Routt County, Colo.; the lignite coal fields of southwestern North Dakota, northwestern South Dakota, and eastern Montana; the Durango-Gallup coal field, in the northwestern part of New Mexico and the adjacent part of Colorado. Brief reports on all of these surveys were prepared for the annual economic bulletin, and detailed reports have been completed and submitted for publication.

In cooperation with the General Land Office an investigation of certain contested coal lands in Utah was undertaken, with a view to the classification of the lands according to their mineral or nonmineral character. During the season surveys were made of the Book Cliffs coal field and of the coal lands in the vicinity of Coalville and Provo. Brief reports were prepared for the annual economic bulletin, and detailed reports were completed and submitted to the General Land Office. During the last four months of the fiscal year the Survey · cooperated with the Department of Justice in the investigation of coal-land frauds in Utah and Colorado. These investigations are still in progress.

A detailed report on the three southernmost oil fields of California was completed and submitted for publication, and a brief report on the recently developed Salt Lake oil fields near Los Angeles was prepared for the annual economic bulletin. In addition, the annual economic bulletin contained the following reports on the fuel resources of the West: The Engle coal field of New Mexico; the coal of the Mount Diablo Range, Monterey County, Cal.; the mineral resources, chiefly coal and lignite, of the Bighorn Mountains and the Bighorn Basin, Wyoming.

Iron ores. In pursuance of the systematic investigation of the iron. ores and iron industry of the United States the following investigations were made during the year in the Rocky Mountain and Pacific Coast States: A reconnaissance of the iron ores of central Colorado, including deposits near Ashcroft and White Pine in the Sawatch Range, those in the Cebolla district south of Gunnison, and in the preCambrian rocks in the vicinity of Salida; the detailed mapping of the deposits of Iron County in southern Utah and a study of the genesis of the ores; an examination of the deposits near Daggett, in San Bernardino County, Cal.; an examination of the deposits in the Seminole Mountains, northwest of Rawlins, Wyo.; laboratory studies of the western iron ores. A brief paper on the iron ores of the western United States and British Columbia was also prepared for the annual economic bulletin.

Miscellaneous economic investigations.-The special investigation of the relation of hydraulic mining and natural stream erosion in the

Sierra Nevada to agriculture, grazing, and other industries in the Sacramento Valley, which is being made in response to a memorial to the President and in cooperation with the division of hydrography, was well advanced, but owing to the intricacy of the problem and the many and conflicting interests at stake additional field and laboratory work will be necessary before the results can be prepared for publication. In connection with this investigation a laboratory has been equipped at Berkeley for the purpose of studying the natural laws which control the transportation of débris by streams, the necessary space, power, and other facilities for the experiments being contributed by the State University of California.

Other economic investigations in the West included the following: A reconnaissance of the mineral deposits of New Mexico, a special report on which was completed and submitted for publication; an examination of the asphalt lands near Thistle Junction, Utah, and of the ozokerite deposits near Colton and Soldiers Summit in the same State, brief reports on which were prepared for the annual economic bulletin, the detailed reports being submitted to the General Land Office.

The following additional brief reports were prepared for the annual economic bulletin: A Nevada zinc deposit; Cement resources of Washington; Some magnesite deposits of California; Gypsum deposits of the Uncompahgre region, Colorado; Gypsum deposits and bentonite of the Laramie Basin, Wyoming; Volcanic ash near Durango, Colo.

GENERAL SCIENTIFIC INVESTIGATIONS.

Geologic map of the United States. In order to meet the demand for revised geologic maps of the United States and of the several States which shall represent the present condition of knowledge, a map of the United States on the scale of 1:2,500,000 was undertaken and considerable progress made in its preparation, also in the assembling of data for the preparation of geologic maps of the States, or of groups of States, on the scale of 1: 1,000,000. The United States map awaits the completion of the base, on which as rapid progress as possible is being made, and the data for the State maps, which will necessarily be more detailed, are being rapidly collated.

Special geologic map of North America.-In cooperation with the Governments of Canada and Mexico, a geologic map of North America on the scale of 1: 5,000,000 is in preparation by the Geological Survey. A preliminary edition of this map will be issued at the expense of the International Geological Congress to be held in the City of Mexico in September, 1906, and an edition will later accompany a professional

paper.

Earthquakes. The record catalog of earthquakes occurring in the United States has been continued. It contains information obtained