A report about minerals fuels and geologies located in parts of the Routt and Moffat counties, Colorado.

A report about phosphates found in the Permian Phosphoria formation of the Rocky Mountains. This area constitutes one of the worlds largest reserves of phosphate.

A report about analyzing the age of igneous rock using its lead-alpha activity.

A report about the geology of the the Crazy Woman Creek area in Wyoming. Rocks of every system except the Silurian and Devonian are present in the area.

A report about geologic names. It contains new names, old names, and changes to names.

A report about the stratigraphy of the Inyan Kara group which reveals how the area has a basic twofold lithogenetic subdivision which has been recognized in equivalent beds elsewhere in the western interior regions.

A report about the Sugar Loaf and St. Kevin mining districts located in Colorado. Most of the bedrock consists of pre-Cambian schist, gneiss, granite, and pegmatite.

A report about the economic geology of four mines located in the Helvetia mining district in the Santa Rita Mountains in south central Arizona. The sedimentary rocks in Helvetia range from Cambrain to Cretaceous.

A report about stratigraphic studies of late Quaternary deposits in the Rocky Mountain region which reveal a widespread uncomformity separating deposits that differ lithologically. The deposits overlying the unconformity contain modern fauna that do not occur in older deposits.

From introduction: The study of the Crystal Mountain district, Larimer County, Colo., is but one phase of this post-World War II pegmatite program, in part carried out by the Geological Survey on behalf of the Division of Raw Materials of the Atomic Energy Commission.

From abstract: Solutions to the Fourier heat equation for quasi-steady periodic flow in a stratified semi-infinite medium can be obtained readily by standard methods. The results have wide application to studies of earth-temperature variations induced by diurnal, annual, and other periodic variations in ground-surface temperature. Much of the previous work on this subject has been interpreted with reference to the solution for the homogeneous case; and this can be seriously in error when applied to stratified earth materials.

From introduction: The area of this report is in the northern part of southeastern Alaska (fig. 39). It includes about 400 square miles on northwestern Chichagof Island, latitude 5747' to 58*15' N. and longitude 135 57' to 136 35' W. It is covered by U. S. Geological Survey Mount Fairweather A-1, A-2, and Sitka D--7 and D-8 topographic quadrangle maps. The writer's geologic investigation was started in 1946 as a continuation of earlier work on the west coast of Chichagof Island by J. C. Reed and R. R. Coats (1941) of the U. S. Geological Survey.

From abstract: The Homer district of the Kenai coal field is about 100 miles southwest of Anchorage, in south-central Alaska. It covers an area of about 1,100 square miles on the west side of the Kenai Peninsula, between Tustumena Lake and Kachemak Bay. The principal settlement is Homer, at the southern end of the district, which is connected by the gravel-surfaced Sterling Highway with the Alaska highway system and The Alaska Railroad, and is also served by ocean transportation and one airline.

From abstract: The Mount Katmai area is on the Alaska Peninsula and comprises the Mount Katmai quadrangle, the Cape Douglas area of the adjoining Afognak quadrangle, and parts of the Karluk and Naknek quadrangles. The area, which includes nearly all the Katmai National Monument, is one of high relief and is drained by streams of preglacial origin. At least two ice advances are indicated by the moraine configuration. Present-day glaciation is restricted to numerous alpine glaciers in the mountain areas. Fifteen recently active volcanoes roughly form a line from Mount Douglas to Martin Mountain.

From abstract: A deposit of rare-earth minerals in the Scrub Oaks iron mine, Morris County, N. J., was mapped and sampled in 1955. The rare-earth minerals are mainly in coarse-grained magnetite ore and in pegmatite adjacent to it. Discrete bodies of rare-earth-bearing magnetite ore apparently follow the plunge of the main magnetite ore body at the north end of the mine. Radioactivity of the ore containing rare earths is about 0.2 to 0.6 milliroentgens per hour.

From abstract: The chromite deposits of the central part of the Stillwater complex lie in a belt 9 miles long between the valleys of Boulder River and the West Fork of the Stillwater River in Sweet Grass County, Mont. The chromite occurs as layers near the middle part of the ultramafic zone in the lower part of the complex. The layers, originally horizontal, have been tilted so that they dip northeastwards at angles ranging from nearly horizontal to nearly vertical, and are cut by many cross faults, the largest with a horizontal offset of 3,000 feet. Investigations by the United States Geological Survey and the United States Bureau of Mines have shown that in this belt there are 5 sections ranging in length from 850 to 3,800 feet along the strike where the continuity and grade of the chromite can be reasonably inferred.

From abstract: Slope and Bowman Counties, N. Dak., include an area of about 2,450 square miles in the southeastern part of the Fort Union coal region of North Dakota, South Dakota, and Montana. In anticipation of a future increase in the demand for the low-rank coal of this region as a fuel for electric power plants and as a raw material for various chemical synthesizing processes, Slope and Bowman Counties were investigated for deposits of lignite that could be mined by large scale strip mining methods. All the lignite beds of economic importance in this area are in the Fort Union formation, particularly in the Tongue River member. The beds are nearly horizontal, dipping about 25 to 50 feet per mile north and northeast from the Cedar Creek anticline in the southwest corner of the area.

From abstract: The mapped area of the Henryetta mining district includes about 168 square miles in Okmulgee County in the east-central part of Oklahoma. The rocks in this district consist of sandstone, silty shale, and shale, and are divided into the Senora formation and the overlying Calvin sandstone of Pennsylvanian age.

From introduction: This report discusses the general geology of the Upper Mississippi Valley zinc-lead district, the distribution of ore deposits, and some relations of the ore deposits to the major geologic features.

From introduction: The principal objective of the program is to make detailed geologic maps of the areas in which important phosphate deposits in the Phorphoria formation occur. It is hoped that the maps will serve both as an aid in selecting possible sites for mining and as a basis for calculating reserves.

From abstract: Devils Tower is a steep-sided mass of igneous rock that rises above the surrounding hills and the valley of the Belle Fourche River in Crook County, Wyo. It is composed of a crystalline rock, classified as phonolite porphyry, that when fresh is gray but which weathers to green or brown. Vertical joints divide the rock mass into polygonal columns that extend from just above the base to the top of the Tower.

From introduction: The exploration project at Christmas was carried on cooperatively by the Geological Survey and U. S. Bureau of Mines. Mr. 0. M. Bishop, Engineer for the Bureau of Mines, examined the property and in his report of June 6, 1942 recommended that six holes be drilled from the 800 level of the mine. The Bureau of Mines began drilling in September 1942, and the Survey investigations began a month later. Since any ore bodies discovered below the 800 level would be inaccessible until a deeper level could be developed, the Bureau and Survey decided to explore from higher levels where resulting benefits could be more quickly realized. Drilling from the upper levels was begun early in 1943.

Abstract: This report abstracts the published information on geologic occurrence and distribution of perlite in the United States. Perlite is important in the growing light-weight aggregates industry. The geology and petrology of perlite are described and brief mention is made of mining, milling, processing, economic factors, and reserve figures where known. A table of analyses of the rhyolitic, latitic, and dacitic perlite, welded tuff, pitchstone, and obsidian is included mainly to show the water content. The index map shows known deposits and the geology of areas in which possible deposits may be found. The locations of processing plants are indicated to show their economic relationship to the deposits and to markets.

From introduction: The Stanford-Hobson area project was undertaken by the United States Geological Survey, in cooperation with the United States Bureau of Reclamation, as part of a program for the geologic mapping and investigation of mineral resources in the Missouri River basin. The field work that is the basis of the ensuing report consisted of mapping the geology and determining stratigraphic relationships in sufficient detail to evaluate the mineral resources, especially the oil and gas possibilities in the area.