From introductory: Report of the survey party on the Great Sioux Reservation for determining any coal-beds of economic value.

From introduction: The present paper is intended as a contribution to our knowledge of a particular phase of metamorphism in eruptive rocks, i.e., that one which is dependent on the secondary development of hornblende by the paramorphism or pseudomorphism of pyroxene.

From letter of transmittal: The present report includes special discussion of the faunas of the Hamilton group and of those below the black shales of the Genesee group is omitted.

From preface: This bulletin is based upon the observations of the Tertiary and Cretaceous strata exposed along the Tuscaloosa, Tombigbee, and Alabama Rivers in the state of Alabama.

From outline: This essay comprises, first, a general discussion of the limitations of the term Eocene as employed in American geology. The two-fold character of the Tertiary (1. Eocene, 2. Neocene) in America is insisted on. After a somewhat extended review of the literature, in which the various opinions upon disputed points are especially considered, a general study of the stratigraphical, paleontological, and topographical characteristics of the Eocene in the various portions of the country is undertaken.

From introduction: This report deals with the Middle and Upper Carboniferous System.

From introduction: The observations recorded in this paper were made during a rapid reconnaissance from east to west through the central part of Oregon in the summer of 1903, and are in continuation of similar work in the same general region previously done by the author, reports concerning which have been published.

From abstract: This report is one of a series of publications by the United States Geological Survey on the Appalachian coal, oil, and gas fields. The area described occupies 227 square miles in Allegheny, Butler, and Westmoreland Counties, in western Pennsylvania, immediately north of Pittsburgh.

From introduction: The purpose of this report is to describe the geology of the Elk Hills and the occurrence of the oil and gas, to trace the movements of oil, gas, and water in the developed areas, and to discuss the oil possibilities of the undeveloped parts. The history of the field and its production also are set forth.

From abstract: The largest single metal-mining operation in the history of mining in Colorado has been developed at Climax, as a result of the increased use of molybdenum in the steel and other industries. Production of molybdenum at Climax was notable for a short period during the World War; it ceased from April 1919 to August 1924 but since then has shown a steady increase. In 1930 from 1,000 to 1,200 tons of ore was milled daily, using only one unit of the 2,000-ton mill. The mine has a reserve of broken ore sufficient to furnish 2,000 tons daily for 3 years and is being developed to continue to furnish this and a still further increased output as the use of the metal may warrant.

From Abstract: Two areas and their included mineral deposits, situated in Josephine County, southwestern Oregon, are described in this report. They lie within the Klamath Mountains, a region which is made up for the most part of rugged ridges trending in various directions but which, when viewed from higher summits, resembles a dissected plateau and is known as the Klamath peneplain. Rocks of both igneous and sedimentary origin are abundant in the districts described. The marine sedimentary rocks of the areas comprise a thick series of Carboniferous strata, with some interbedded volcanic rocks, and portions of the Galice formation, of Jurassic age, and of an Upper Cretaceous formation. The rocks of fluviatile origin include Tertiary conglomerate, Pleistocene valley fill, termed the " Llano de Oro formation," and somewhat later Pleistocene gravel and alluvium, in part glacial debris. Recent gravel is found along the present streams. The igneous rocks include several varieties of greenstone of probable Paleozoic and Mesozoic age and serpentine of late Jurassic or early Cretaceous age.

From abstract: The Girdwood district has been known for about 35 years to contain placer gold, but the source of the gold in veins was not discovered until about 1909. When the Alaska Railroad was completed through Girdwood it was hoped that the improved transportation facilities would enable the lode mines to operate at a profit and also to furnish tonnage to the railroad. Production from the quartz veins, however, has been negligible, although one placer mine has been operating steadily for several years.

From abstract: The Kantishna mining district is about 90 miles west of McKinley Park station on the Alaska Railroad. The part of the district covered by this report comprises an area of about 72 square miles in the form of a strip 6 miles wide and 13 miles long. The bedrock is mainly a metamorphic series of rocks which within the area has been differentiated into a quartz-muscovite schist and a calcareous faces that ranges from limestone to chlorite schist. A few small dikes of quartz porphyry and diabase intrude the schist. The general structure trends N. 700 E., and from an axis that extends from Eldorado Creek northeastward to Spruce Peak the schistosity dips to the northwest and southeast. It is along this axis that the heaviest mineralization has occurred.

"To the end of 1930 Alaska, according to the records of the Geological Survey, had produced placer gold to the value of $258,962,000 from mines widely scattered throughout its length and breadth. The distribution of the placers from which the gold was recovered has been stated in more or less detail in the annual summaries published by the Geological Survey on the mineral industry of Alaska and also in its more complete reports on many of the individual mining districts. Although these summaries and reports have furnished information regarding the larger regions, they have not always given specific details regarding the smaller districts. Furthermore, there has been no recent attempt to assemble and publish in one place the scattered statistics regarding the placer-gold production by years and by regions and districts. The purpose of the present report is to set forth in condensed but comprehensive form a summary of the placer-gold production of Alaska so far as it can be determined from the available official records."

From abstract: This report presents the results of a reconnaissance of most of the mining districts of Oregon east of the Cascade Range, with the exception of the districts in the Sumpter quadrangle. The districts described are distributed through an area roughly coincident with the Blue Mountains, which extend over much of the northeast quarter of the State.

From abstract: The Moose Creek area is in the western part of the Matanuska Valley, in south-central Alaska, about 165 miles by railroad north of the coast at Seward. Coal deposits in the valley have been known since the early 1890's, and there have been producing mines since 1916, but the annual production is only about 40,000 tons, or less than one-third of the total amount consumed in the Territory. Early in 1931 Congress authorized the investigation of mineral resources in areas tributary to the Alaska Railroad, which is Government owned and operated, for the purpose of stimulating development and hence increasing the traffic and revenue of the railroad. The technical work of carrying on these studies was entrusted by Col. O. F. Ohlson, general manager of the railroad, to the United States Geological Survey. One of the investigations undertaken was that of the Moose Creek area, where small coal mines are in operation. Difficulties have been encountered in these mines, owing to the faulted character of the formation, which causes unproductive work in mining and also produces a large percentage of fine coal, which is unsuitable for sale in distant markets. Field examination indicated that more favorable mining conditions …

From abstract: The Curry district lies on the south flank of the Alaska Range, on the southeast side of Mount McKinley. Most of it is west of the Alaska Railroad. The eastern portion can be easily reached from several points along the railroad route, but the western portion is much more difficult of access, owing to the numerous glacial streams and the rugged topography. The relief of the area is great, the elevation ranging from 500 feet along the Chulitna River to 20,300 feet at Mount McKinley. The Chulitna River, a tributary of the Susitna River, drains the larger part of the area described. It flows in a broad valley in the eastern part of the district, and here the maximum relief is about 3,000 feet. The western part of the district is very rugged, with numerous peaks over 6,000 feet in elevation which have sheer slopes and almost unscalable pinnacles. Winding down through this maze of rugged mountains are four major valley glaciers-Eldridge, Buckskin, Ruth, and Tokichitna-and many tributary and smaller glaciers. Practically the entire district, with the exception of the higher peaks and ridges, has been glaciated. Timber grows along the main streams and extends to an elevation …

From abstract: The report describes the geology and coal deposits of the southwestern part of the San Juan Basin, N.Mex. The field lies northeast of the town of Gallup, on the Atchison, Topeka & Santa Fe Railway, and is an irregular tract of about 630 square miles in central and west-central McKinley County; it includes the southeast corner of the Navajo Indian Reservation.

Abstract: During the spring of 1932 an opportunity was offered by the United States Navy for a geologist to accompany an expedition organized to make a reconnaissance of the western part of Alaska Peninsula and the Aleutian Islands. This expedition visited several localities the geology of which was little known. It was found, as had already been expected, that the islands west of Unimak Pass are composed mainly of basic volcanic lavas and fragmental materials, into which have later been injected dikes, sills, and considerable masses of intrusive rocks, some of which are of acidic types and of granitic texture. These westward islands are bordered both to the north and south by depressions 2,000 fathoms or more in depth, and the islands have apparently been built up from that depth by the ejection and extrusion of volcanic materials since early Tertiary time. No rocks of proved pre-Tertiary age were seen, and the only sedimentary materials present may well have been derived from the erosion of the volcanic islands after they were built up above sea level. On the Alaska Peninsula pre-Tertiary sediments through which the volcanic materials broke to the surface are abundantly present. There is evidence that all the …

From introduction: Two field parties, one topographic, the other geologic, were engaged in making surveys in the section of the Alaska Range between the Nabesna and Big Tok Rivers in 1934. Most of the area surveyed was on the northeast side of the range, within a drainage area that is tributary to the Nabesna and Tanana Rivers, but it also included a small part of the Copper River Basin.

From abstract: This report summarizes the results of a reexamination, in 1930, of the Contact mining district, in Elko County, northern Nevada. A report published as a result of a visit in 1910 summarizes the major features of the geology of the district, and the principal new data in the present paper pertain to mining development occasioned by the completion of a railroad through the camp in 1925.

From abstract: The Santa Rita mining area (pl. 1), covering 35 square miles of semiarid mountainous land, lies within the Silver City 30-minute quadrangle, Grant County, N. Mex., and includes the most productive part of the Central or Hanover mining district. Ore was produced in this district as early as 1804 and production continued intermittently for a century before the developments were undertaken that led to large-scale copper mining, which began in 1912. The output of zinc, lead, and iron increased markedly about the same time.

From introduction: The purpose of this paper is to describe the geology and mineral resources of a part of the Copper River Basin between the Richardson Highway and the valley of the Klutina River, together with small areas east of the highway and west of the river. For convenience in reference this area is called the Tonsina district, as the Tonsina River and Tonsina Lake are conspicuous local geographic features, and the Tonsina Road House, on the highway at the crossing of the river, is one of the oldest and best-known settlements in the Copper River Basin.

From introduction: The present report describes the general geology and the economic resources of the [Mount Taylor Coal] field. The area adjoining this on the west was mapped by Sears; the area adjoining on the north was mapped by Dane.