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Paleomagnetic and potassium-argon studies support geologic evidence that the lower member of the Bandelier Tuff was deposited 1.4 m.y. ago. The upper member erupted about 1.0 m.y. ago and was followed by caldera collapse which formed the 12- to 14-mile diameter Valles Caldera. Postcaldera activity which resulted in the eruption...

No abstract available. ...

Resurgent cauldrons are defined as cauldrons (calderas) in which the cauldron block, following subsidence, has been uplifted, usually in the form of a structural dome. Seven of the best known resurgent cauldrons are: Valles, Toba, Creede, San Juan, Silverton, Lake City, and Timber Mountain. Geologic summaries of these and Long...

Shatter cones abound in the central uplift of Sierra Madera and they occur as far as 6.5 kilometers from the center. Apical angles average near 90 degrees. Whole cones and full cones represented by diversely oriented cone segments in any structural block show relatively uniform orientations of axes and a...

No abstract available....

Several metamorphic and plutonic events have been recognized in the Klamath Mountains utilizing potassium-argon and rubidium-strontium mineral and whole-rock ages. The oldest known metamorphic event in the region produced the Abrams Mica Schist and the co-extensive Salmon Hornblende Schist. Strontium evolution diagrams indicate that the age of primary metamorphism of...

Polymineralic sulfide grains, composed principally of Fe sulfide and Fe-Cu sulfide, with magnetite, have been studied mineragraphically and by electron probe, and interpreted in terms of experimental data for the system Fe-Ni-Cu-S. The three main phases are monosulfide solid solution, a Cu-Fe sulfide (solid solution) with composition near cubanite, and...

Photographs of a Late Cretaceous species of Aquilapollenites illustrate the usefulness of the scanning electron microscope (SEM) for the study of fossil pollen. The SEM has the advantages of great depth of focus and wide range of magnification; using present techniques, its use for the study of unsectioned specimens is limited to the observation of surface detail....

Thick salt deposits are present in the Middle Pennsylvanian Paradox Member of the Hermosa Formation in the Paradox Basin of southeast Utah and southwest Colorado. Data suggest that the original thickness of these deposits was from 5000-6000 feet. Locally, however, these deposits have been subjected to intense deformation and flow, resulting in thicknesses as great as 14,000 feet. Each salt bed is part of a series of partial and...

Time residuals from 75-km segments of 18 crustal seismic-refraction profiles in the Basin and Range province are used to investigate the validity of the linear-regression model and to make large sample estimates of the variance in the travel time distributions.A formula for unbiased estimates of velocity uncertainty is derived, assuming a...

In the 3000-square-mile area of southeastern Mississippi and northeastern Washington Parish, Louisiana, which has Tatum dome in its center, rocks of known Jurassic to Recent age are more than 20,000 feet thick. They are underlain by an unknown thickness of Louann Salt of Jurassic (?) age. The age, thickness, and nature of the sedimentary rocks between the salt and the basement, as well as the character...

The isotopic composition of lead in feldspar varies widely from pluton to pluton of the Late Cretaceous Boulder batholith, encompassing the following ranges in isotopic values: 16.9-18.1 for Pb 206/Pb 204; 15.4-15.7 for Pb 207/Pb 204; and 37.7-38.5 for Pb 205/Pb 204. Although each pluton has a characteristic isotopic composition, the fact that Pb 206/Pb 204 for the Butte...

It is shown that a thermodynamic analogy can be set up for structurally cyclic as well as for noncyclic river nets that satisfy Horton's law of stream numbers. In the latter case, the microcanonical formalism of statistical thermodynamics has to be used. ...

No abstract available. ...

No abstract available....

Dye tracers have been used in Oregon in the Collection of hydrologic data on 2,350 miles of stream channels in the Long Tom, Umpqua, Willmette, and John Day River basins, and in the Carmen‐Smith power tunnel. These investigations demonstrated the usefulness, of dye tracers for determining: (1) estimates of traveltimes and travel...

No abstract available....

Ultimate sources of uranium are believed to be either fluids from Morrison volcanoes (not demonstrable) or labile constituents in the Jackpile Sandstone. Petrographic studies indicate considerable pre-Dakota diagenesis, which would have made uranium in feldspars, heavy minerals, and volcanic debris available. Deposition of uranium occurred while host sandstone was near...

Electric‐analog or digital‐computer models are used to compute the effect of ground‐water withdrawal or recharge on streamflow. The results can be generalized on a map showing lines of equal elapsed time. The lines indicate the time of recharging or discharging that is needed to affect the streamflow by a given fraction of the...

The possibility of leakage of fluids into or out of fluid inclusions subjected to large pressure gradients has always been considered a serious problem in the interpretation of inclusion data. As previous experimental evidence on leakage was contradictory, new experiments were performed. Inclusion vapor bubble diameters in twelve quartz crystals (≤ 3 mm; 8 localities), not sawn, ground or polished, were measured....

The leads in feldspars from the main Tertiary intrusive bodies in each of three mining regions in Utah are isotopically similar to the lead deposits immediately associated with them. These deposits are the largest and also the least radiogenic in each region, whereas the smaller deposits are more radiogenic. Throughout each region the 'ore leads appear to be mixtures in various proportions of lead derived from the intrusive...

The lethal effects of heptachlor on bobwhites (Colinus virginianus) were studied at the Patuxent Wildlife Research Center during 1962 and 1963. A pair of adult birds was placed in each of 32 wire-covered field pens (20 x 50 x 61/2 ft) in May, 1962, and in 36 additional pens in...

A 6-year study to determine the effect of nest-predator removal on waterfowl nesting success was conducted at the Agassiz National Wildlife Refuge in northwestern Minnesota from 1959 through 1964. Predators were removed from the west side of the Refuge while the east side served as a control area. At the...

Twenty samples of hornblendes from rocks of 14 plutonic units in the central Sierra Nevada and Inyo Mountains, California, have been studied in detail. Optical, density, single-crystal and powder X-ray diffraction, and major and minor element chemical data are reported.The compositions of the hornblendes show only limited correlation with the...

An aquifer test and analyses of water samples, showed that the anomalous water quality of a municipal well was caused by leakage from a nearby abandoned well tapping another aquifer. ...