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At least 1,063 records · Page 59Linked to original sources
USGS1976

Enhydra and Enhydriodon from the Pacific Coast of North America

Two lineages of the "crab-eating" otter Erihydriodon , from the Old World Miocene and Pliocene, are suggested by the fossil record. One appears to lead to the late Pliocene Enhydriodon sivalensis from Villafranchian-equivalent beds in India and can be characterized by the presence of a parastyle on P 4 and by the location of the protocone of this tooth, which is located as far lingually as is the hypocone. In the other lineage no parastyle is developed on P 4 , the anteroposterior length of the carnassial blade is progressively reduced while the transverse width is increased, and the protocone of P 4 remains in its primitive position anterolateral to the hypocone. The second lineage, insofar as it is known, seems to lead toward the living sea otter Enhydra , particularly so because of the evolutionary direction shown by two species of Enhydriodon from the late Miocene and late Pliocene of California.

Pacific Ocean↗
USGS1975

Recurrent geothermally induced debris avalanches on Boulder Glacier, Mount Baker, Washington

Avalanches of snow, firn and hydrothermally altered rock and mud have been released six times since 1958 from Sherman Peak, part of the crater rim south of the main summit of Mount Baker, Wash. The avalanches traveled nearly identical paths 2.0-2.6 km down Boulder Glacier on the east slope of the volcano. Debris from at least one past avalanche can be seen as a thin bed of acidic mud in the glacier terminus. Fumaroles. thermal springs, and areas of warm ground, some of which are subglacial, are concentrated in the crater and were mapped by aerial infrared thermography. The outgoing radiant flux per unit area from a cluster of infrared anomalies within 50-150 m of the avalanche source was estimated to be 319 W m -2 (7,620 μ cal cm -2 s -1 ) in November 1972, which is sufficient to account for observed ice perforations. In addition vapor emission, not apparent in thermography, was observed along the source margin after the avalanche of August 1973. The principal conditions that produce the avalanches are considered to be the large accumulation of snow and firn on top of hydrothermally altered clay-rich ground at Sherman Peak and the saturation near the ground-firn interface by melt water produced both by summer snow ablation and by geothermal emission. The periodic avalanches have a potential for impounding water in the crater in addition to ponded water already known to occur. Sudden release of impounded water could present a danger to the Boulder Creek valley below.

Washington↗
USGS1975

Mobilization of iron in water in the Magothy aquifer during long-term recharge with tertiary-treated sewage, Bay Park, New York

Tertiary-treated sewage (reclaimed water) has been recharged by well into the Magothy aquifer at Bay Park, N. Y., intermittently since 1968. The longest of 13 recharge tests, the subject of this report, lasted 84.5 days. This was sufficient time for the reclaimed water to reach an observation well 200 ft (61 m) from the recharge well. Although the iron concentrations of the reclaimed water and the native water were less than 0.4 mg/l, the iron concentrations of samples from observation wells 20, 100, and 200 ft (6, 30, and 61 m) from the recharge well at times approached 3 mg/l. Source of the ii'on is pyrite that is native to the aquifer.

New York↗
USGS1976

Mississippian history of the northern Rocky Mountains region

The Mississippian history of the northern Cordilleran region of the United States consists of two principal depositional cycles separated by a cycle of epeirogenic uplift and erosion. Each depositional cycle is divisible into phases that represent significant changes in depositional patterns. During Cycle I (early Kinderhookian-early Meramecian), predominantly carbonate and evaporite deposition took place on a broad cratonic shelf bordered on the east by land and on the west by a deep trough that received terrigenous sediments from an adjacent western landmass. Kinderhookian transgression was followed by regression during the Osagean and early Meramecian. Regional uplift during latest early Meramecian time (Cycle II) drained the shelf area and caused the sea to be confined to the western trough. During Cycle III (middle Meramecian-Chesterian), the sea again transgressed onto the craton, which was differentiated into the Big Snowy-Williston, Wyoming, and Uinta basins, where terrigenous and carbonate sediments were deposited. The Big Snowy-Williston basin was uplifted during latest Chesterian time and lost its identity, but the Wyoming basin continued to expand into the Pennsylvanian, when it engulfed most of the Cordilleran platform and breached the Transcontinental arch. Application of generalized carbonate, terrigenous, and evaporite depositional models results in specific models that explain the Mississippian depositional patterns.

Colorado, Idaho, Montana, Nebraska, Nevada, North ↗
USGS1975

Changes in concentration of certain constituents of treated waste water during movement through the Magothy Aquifer, Bay Park, New York

Approximately 7 million gallons (27 million litres) of tertiary-treated sewage (reclaimed water) was injected by well into the Magothy aquifer and was subsequently pumped out. As the reclaimed water moved through the aquifer, concentrations of certain dissolved constituents decreased as follows: Total nitrogen, 7 percent; methylene blue active substances, 49 percent; chemical oxygen demand, 50 percent; and phosphate, more than 93 percent.

New York↗
USGS1975

Norman Creek, a source of recharge to Maramec Spring, Phelps County, Missouri

Rhodamine WT dye was used to trace the subsurface movement of water from Norman Creek, a losing Ozark stream, to Maramec Spring, a straight-line distance of 8.7 mi (14.0 km). Grab samples and activated charcoal packets were used to check possible emergent points of the dye. The leading edge of the dye reached Maramec Spring 68-75 days after the dye injection, and the peak concentration reached the spring 82-93 d after injection. Small quantities of dye were still being recovered at the spring 114 d after injection and 39-46 d after the dye first arrived at the spring. Computed average velocities, assuming straight-line travel, are 0.47-0.42 ft(0.14-0.13 m)/min for the leading edge and 0.39- 0.34 ft(0.12-0.10 m)/min for the peak. This apparent rate of travel compares favorably with other recent subsurface tracing studies in southern Missouri which generally range from 0.4 to 25 ft(0.12 to 7.6 m)/min.

Missouri↗
USGS1976

Marine diatom and silicoflagellate biostratigraphy of the type Delmontian Stage and the type Bolivina obliqua Zone, California

Investigation of the marine diatom and silicoflagellate biostratigraphy of the type Delmontian Stage and and type Bolivina obliqua Zone in California shows that the type Delmontian Stage is equivalent to part of the supposedly older Mohnian Stage and is early late Miocene. The type Bolivina obliqua Zone, which conformably overlies the type Mohnian Stage, appears to be early Pliocene.

California↗
USGS1975

Combining estimates of low-flow characteristics of streams in Massachusetts and Rhode Island

The number of base-flow measurements needed to meet specified accuracy goals for estimating low-flow characteristics at ungaged sites can be reduced by combining an estimate based on a regression of base-flow measurements on discharges from a nearby continuous long-term gaging station with an estimate based on a regional relationship developed from regressing the low-flow characteristics on basin characteristics. The estimates should be combined by weighting each inversely with its variance from the true value. Empirically estimated values of variance of the estimated 7- day, 10-year low flow from its true value indicate that more than six or eight base-flow measurements add" little to the confidence with which such an estimate is made.

Massachusetts, Rhode Island↗
USGS1975

Adjustment of logarithmic flood-frequency statistics for gaged California streams to minimize the time sampling error

Methods for adjusting logarithmic flood-frequency statistics for gaged streams to minimize the time sampling error that is inherent in short records are discussed. Statistical procedures for adjusting the mean and standard deviation of a short-term array of annual peak discharges are already well established; two standard sets of equations for utilizing the additional information contained in longer records of peak discharge observed at nearby gaging stations are given. A standard method for adjusting the coefficient of skew does not exist, and consequently a special technique for estimating the long-term value of that statistic was developed for this study. Regional equations were developed that relate the logarithmic skew coefficient to logarithmic transformations of mean annual basinwide precipitation and mean annual peak discharge per square mile. The technique appears to be satisfactory for use in the greater part of California, where over large areas the peak discharge in any year is usually associated with a single widespread general storm or with a series of such storms where snowmelt runoff is involved rather than with localized precipitation events.

Journal of Research of the U.S. Geological Survey↗
USGS1975

Generation of potassium-poor magmas in the northern Sierra Nevada and the Svecofennian of Finland

Comparison of the evolution of magmas in the Precambrian of southwestern Finland with that in the Paleozoic and Mesozoic of the northern Sierra Nevada brings out features that may clarify the origin of potassium-poor silicic magmas. In the northern Sierra Nevada, Paleozoic sodarhyolitic effusive rocks and associated trondhjemite represent silicic differentiates of andesitic magmas formed near a Benioff zone. These potassium-poor magmas were formed early, before thickening of the crust, and were followed by basaltic and rhyolitic magmas with normal potassium content. In southwestern Finland, where 70 percent of the area is covered by silicic and intermediate plutonic rocks, the early synkinematic intrusive masses are trondhjemitic and the later ones are granitic with eutectic ratios of quartz, plagioclase, and potassium feldspar. The latest granites are exceptionally rich in potassium feldspar. The oldest rocks, cordierite-garnet-sillimanite gneisses and interbedded metavolcanic rocks, are folded on gently plunging axes that steepen diapirically around large late-kinematic plutonic masses. Trondhjemite occurs as thin sheetlike masses parallel to the folded bedding and could not have traveled far without losing its initial heat. Therefore it seems that the trondhjemitic magma was formed at shallow depths. By analogy with the shallow depth of early magma generation in the northern Sierra Nevada, it is suggested that the trondhjemitic magmas in Finland formed at mantle depths near a Benioff zone or at the base of the early thin crust at pressures where phlogopite or biotite was stable. Later, after thickening of the crust above, potassium from the biotite was released, making the late kinematic magmas rich in potassium. A plate-tectonic model of an island-arc environment explains the coeval age of the Svecofennian and "Karelian" foldbelts and the increase of potassium with decreasing age in the extrusive and intrusive magmas.

northern Sierra Nevada, Svecofennian block↗
USGS1976

Sediment-filled pots in upland gravels of Maryland and Virginia

Pot-shaped depressions filled with sandy clayey silt are found in "Upland" gravels (previously termed Brandywine) of probable Miocene age, in northeastern Maryland and in Virginia near Washington, D.C. The pots are about 7 ft (2m) deep and commonly are about as wide. In plan, many are strongly elliptical. Sides are steep or even bulbous, and the filling in some pots shows faint stratification paralleling the sides. Strata in the enclosing gravel commonly bend downward and are thinner beside and below the pots. The gravel deposits are remnants of alluvial deposits of the ancestral Susquehanna and Potomac Rivers. All the pots are at the present gravel surface. We suggest that the pots originated when seasonal frost in an overlying layer of sandy clayey silt provided a confining upper layer. The freezing plane in the silt moved downward, reaching the gravel at some points before others. Water in the gravel moved toward the freezing plane by capillarity or by cryostatic head, forming ice lenses in the silt. Each winter, ice growth forced unfrozen clayey silt a short distance downward and outward into the gravel, increasing the irregularity of the silt-gravel contact and promoting more rapid movement. The pots probably reflect some centuries of growth, probably during the Illinoian Glaciation.

Maryland, Virginia↗
USGS1976

Ocher as a prospecting medium in the Montezuma district of central Colorado

Ocher occurs widely In the Montezuma district as small sinters and as bedded deposits of bog iron and ocher-cemented conglomerates. The iron of the ochers is derived from pyrite-rich veins and from pyritic hydrothermally altered rocks. Trace amounts of ore metals in the ocher and its admixed detritus are partly from the pyritic source rocks but also include contributions from other rocks and ores in the watershed, both during and after formation of the ocher deposit. Ocher is evidence for the presence and character of the generally ill exposed pyritic rocks, which are important, in evaluating the porphyry-metal system of ore deposits. The trace-element composition of the ocher is at best a qualitative guide to the ore metals present in the provenance of the ocher deposit but not to their abundance or necessarily to their mode of occurrence.

Colorado↗
USGS1975

Progressive metamorphism of schists recovered from a deep drill hole near Fairbanks, Alaska

In 1965, a deep test hole drilled near Eielson Air Force Base, Fairbanks district, Alaska, penetrated 9,774 ft (2,979.1 m) into schists of the metamorphic complex of the Yukon-Tanana Upland. Cores recovered from the test hole show that the section is dominated by calc-magnesian rocks with subordinate pelitic schists. Pelitic mineral assemblages define a progressive increase in metamorphic grade with depth, from the garnet to the kyanite isograd. Diopside first appears in the calc-magnesian schists that were cored at a depth of 9,766 ft (2,976.5 m), indicating the onset of the reaction: Tremolite + 3 calcite -f- 2 quartz→5 diopside + 3CO 2 +H 2 O. Ubiquitous staurolite and rare andalusite occur in the kyanite-bearing pelitic schists. Andalusite appears to have crystallized under postkinematic conditions, and the staurolite is apparently of both synkinematic and postkinematic origin. Hornblende and biotite from calc-magnesian schists sampled at depths of 7,142½ ft (2,176.9 m) and 9,766 ft (2,976.5 m) gave 40 K/ 40 Ar ages of 140±8 and 57.3±1.9 m.y., respectively. The hornblende age is believed to represent the age of the latest synkinematic metamorphism, and the biotite age appears to be an anomalously young one related to the outgassing of argon from biotite at greater depth in the section. Recent experimental data on andalusite-kyanite-sillimanite and staurolite equilibria and the stability field of calcite+quartz+tremolite versus diopside in calc-magnesian rocks suggest that the rocks recovered from the 8,218- to 9,770-ft (2,504.7- to 2,977.7-m) interval were synkinematieally recrystallized at crustal depths of 17 to 19 km and at temperatures of 515° to 580°C; the present thermal gradient (31.5°C/km) is similar to that which accompanied metamorphism in Jurassic time.

Alaska↗
USGS1976

A reconnaissance study of the uranium and thorium contents of plutonic rocks of the southeastern Seward Peninsula, Alaska

Large granitic Cretaceous plutons are exposed along and adjacent to an arcuate belt of igneous and high-grade raetamorphic rocks in the southeastern Seward Peninsula of Alaska. Reconnaissance studies of these plutons have shown that the Darby pluton has well above average amounts of uranium and thorium (11.2 ppm and 58.7 ppm, respectively), the Kachauik pluton contains average to above average uranium and thorium (5.7 ppm and 22.5 ppm, respectively), and the Bendeleben pluton contains average amounts of uranium and thorium (3.4 ppm and 16.7 ppm, respectively). The three plutons show compositional and textural differences indicative of different source materials that may have controlled the distribution of uranium and thorium. The high uranium and thorium contents of the Darby pluton, similar to those of the Conway Granite of New Hampshire which has been mentioned as a possible low-grade thorium resource, suggest that this pluton may be a favorable area for economic concentrations of uranium and thorium.

Alaska↗
USGS1976

Thin-skinned tectonics and potential hydrocarbon traps: Illustrated by a seismic profile in the Valley and Ridge province of Tennessee

Seismic data, although limited to a small part of the western half of the Valley and Ridge province in Tennessee, confirm that the structural style is thin-skinned and that there is a fundamental change from west to east in both the total section preserved and the structural complexities that exist in the subsurface. Cambrian to Upper Ordovician rocks in the Valley and Ridge province have been thrust westward over a 4-mile (6.4-km) projection of Cambrian through Mississippian rocks of the Appalachian Plateau. Structure within the plateau projection is characterized by splay anticlines, whereas structure in the Valley and Ridge is dominated by a series of imbricate thrust sheets containing isolated fault-bound masses of Cambrian sandstone and shale. Both splay anticlines and large fault-bound masses of rocks preserved in the subsurface in east Tennessee may be favorable fracture-porosity traps for the accumulation of hydrocarbons.

Tennessee↗
USGS1975

Phosphate fertilizer materials in Colombia; imports, uses, and domestic supplies

The distribution of potentially economic phosphate deposits and the locations of major users of phosphate products in Colombia are some of the economic factors that indicate the capability of the deposits to supply domestic demands. Much research is required to determine the types of processing plants needed and to outline changes from standard procedures, but there is little doubt that with proper planning a phosphate chemical industry could be developed that would supply domestic demands for the forseeable future.

Journal of Research of the U.S. Geological Survey↗
USGS1975

Description of the geoelectric section, Rattlesnake Hills unit 1 well, Washington

A complex 64-in. normal log from the 3,249-m-deep Rattlesnake Hills well was digitized and reduced to a form resembling a simple resistance log. The simplified form of the log made it possible to recognize three major geoelectric intervals in the well that were not apparent on the original log. The apparent resistivity values from each geoelectric interval are grouped into a frequency-distribution table, where midpoints of the class interval are corrected for the effects of hole diameter and mud resistivity. Using corrected class-interval midpoint resistivities, first-approximation values are calculated for five geoelectric parameters: total transverse resistance, total longitudinal conductance, average longitudinal resistivity, average transverse resistivity, and the coefficient of anisotropy. Comparison of anisotropies, resistivity variations, and resistivity-frequency polygon shapes indicates quantitative differences among the three geoelectric intervals.

Washington↗