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The ore bodies of the Highland-Surprise Mine are replacements along shear zones in quartzose slate, quartzite, and phyllite of the Prichard Formation of the Belt series (Precambrian). Pyrite, arsenopyrite, pyrrhotite, sphalerite, chalcopyrite, and galena are the chief metallic minerals and were probably deposited in that order. Temperatures of formation were...

Hornblendes in amphibolite interlayers in the paragneiss of the northwest Adirondack Mountains undergo systematic changes in color, composition, and density during progressive metamorphism from almandine-amphibolite to hornblende-granulite facies. In contrast, indices of refraction of the hornblendes remain about constant. In the almandine-amphibolite facies the amphibolite layers have the bulk composition of a saturated basalt and...

Late Cretaceous Tuscaloosa Formation occurs as discontinuous remnants that cap many of the ridges in the Western Highland Rim. Typically the formation consists of well-rounded, poorly sorted chert gravel which is trimodal in size distribution. The gravel fraction (mode 15 to 40+ mm) consists of Devonian and Mississippian chert and a small percentage of...

During experiments on sediment transport and resistance to flow with a uniform 0.33-mm sand, data were recorded on the movement of individual rocks having intermediate diameters from about 0.1 to 0.5 foot. The experiments were conducted in a flume 2 feet wide by 60 feet long and for most runs, depth was held...

The design and operation of a microscope freezing stage developed for use at magnifications up to 500X are described. It makes possible studies of low-temperature phase changes such as the freezing of a saline water phase, and hence an estimate of the total salt concentration, in fluid inclusions as small as 10 microns (10-6 milligram in...

Massive and disseminated pyrrhotite-chalcopyrite-pyrite ore replaced a fault zone in Precambrian Carolina Gneiss of Keith (1). Closely following sulfide deposition, vein sulfides and silicates in the wall rock were recrystallized under a rising temperature gradient to coarse-grained unoriented aggregates that contain late pyrite porphyroblasts in pyrrhotite. Boudinage, dilation, and flow structures are common....

Gold, silver, copper, and lead-bearing veins, non-radially zoned, occur just beyond the southern and western margins of the Searchlight, Nevada, quartz monzonite stock. Seven samples of the quartz monzonite and purified individual constituent minerals of the rock, representing apophyses and marginal and interior parts of the intrusive mass, were analyzed petrographically...

No abstract available....

No abstract available. ...

No abstract available....

During early Late Cretaceous the area of the northern Mississippi Embayment was occupied by a structural and topographic dome standing nearly 1000 feet above sea level. Rocks as old as Cambrian were exposed on its crest. Downwarping of the dome, which commenced in Late Cretaceous time, resulted in the development of the Mississippi Embayment syncline, now filled...

An investigation of some aeromagnetic anomalies in north-central Montana shows that remanent magnetization is the dominant factor in anomalies over some rocks and a contributing factor in anomalies over others. In volcanic rocks, remanence is commonly south-seeking down and has an intensity approximately ten times the induced intensity of magnetization. Remanence is shown to be...

A trend toward increasing use of test drilling and subsurface exploration is resulting in a decreasing reliance on human experience in coping with problems in hydrogeology. Application of "observation and inference" and discreet abstraction of readily available data will solve more problems than is now realized. ...

The name jasperoid has been applied to rocks that consist mainly of silica and that have formed by replacement. This paper considers only those jasperoids formed by replacement of limestone. Major problems involved in the origin of such jasperoid include: source of the silica; nature of solutions that dissolve, transport, and precipitate silica; and...

No abstract available....

This article discusses the results of a controlled field testing program, which indicated that definite hydraulic and other advantages may be gained from induced recharging as practiced at Kalamazoo, Michigan. Results include the following: water levels and artesian pressures can be maintained at high stages, the results are lower pumping...

In the Balmat area in northern New York, tabular deposits of sulfide minerals parallel the layering in folded, siliceous magnesian marbles of a metamorphic complex commonly referred to as the Precambrian Granville Series. Sphalerite, pyrite, and, locally, pyrrhotite and galena have replaced the carbonate minerals in parts of the marble units. The contacts...

No abstract available....

No abstract available....

A statistical analysis is made of the sequences of annual tree ring widths and indices. The expected value of growth during any year is shown to be proportional to the standard deviation of the growth, so that the coefficient of variation is a measure of the sensitivity of the growth of a <span...

Precise measurements of fluctuations of ground-water temperature based on monthly readings in shallow glacial-outwash aquifers may be used to study ground-water movement and recharge. An increase in storage in the shallow basin of Okabena Lake, Worthington, Minnesota, permits the water to cover a much larger area and probably increases the opportunity for infiltration of...

A prominent aeromagnetic anomaly in Randolph County, Indiana, suggests the existence of a dikelike structure within the Precambrian basement rocks. Because of the ambiguity inherent in magnetic interpretation, a unique solution for the parameters involved (depth of burial, geometric configuration, and magnetic susceptibility of the mass producing the anomaly) is impossible. However, if one of the <span...

In 1958 the U.S. Geological Survey and the U.S. Weather Bureau jointly conducted a study of tritium fallout distribution over the continental United States, Alaska, and Puerto Rico. The observation period extended from early April to late July in most areas. While this was insufficient to cover the decay side of the...

A contour map of the Precambrian surface for a part of northeastern New Mexico has been prepared from aeromagnetic, gravity, and drill-hole data. The area extends approximately from the Colorado border south to latitude34° N., and from the foothills of the Sangre de Cristo Mountains east to longitude 104° W. Thirty-seven...