Publications
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Comparison of the TRM of the Yellowstone Group and the DRM of some Pearlette ash beds
Air fall ash beds (Pearlette) originating from rhyolitic eruptions in the Yellowstone‐Island Park region of Wyoming and Idaho are discontinuous but widespread throughout the western United States. Accumulation and deposition of ashes occurred in low‐energy fluvial and lacustrine environments. These ash beds have been correlated, according to their chemistry and remanent magnetism, with specific er
Authors
Richard L. Reynolds
The determination of snow avalanche frequency through tree-ring analysis and historical records at Ophir, Colorado
Tree-ring analysis can be a reliable method of determining past snow avalanche events when good historical records are lacking. Characteristic features in the tree-ring record indicative of disturbance include: (1) the occurrence of reaction wood, (2) abrupt changes in growth rate, (3) age of scars caused by avalanche impact, (4) age of trees in reforested tracks, and (5) examination of a “new lea
Authors
Paul E. Carrara
Emplacement temperatures of unsorted and unstratified deposits of volcanic rock debris as determined by paleomagnetic techniques
Unsorted and unstratified deposits of volcanic rock debris typically flank recently active stratovolcanoes. It is often difficult, using standard geologic procedures, to establish whether a particular deposit was emplaced by a pyroclastic flow, lahar, rock avalanche, or glacier. Determination of the emplacement temperatures of clasts contained in the deposit aids in discriminating among some of th
Authors
Richard P. Hoblitt, Karl S. Kellogg
Origin of a South Texas roll-type uranium deposit; I, Alteration of iron-titanium oxide minerals
The detrital Fe-Ti oxide minerals and their authigenic alteration products in samples from cores spanning 1.7 km across a roll-type uranium deposit in the mid-Tertiary Catahoula Tuff, south Texas, record important information on host-rock preparation and on development of the altered tongue of the deposit. In reduced rock, in front of and enveloping the altered tongue, iron disulfide minerals (pyr
Authors
Richard L. Reynolds, Martin B. Goldhaber
Origin of a South Texas roll-type deposit; II, Sulfide petrology and sulfur isotope studies
Petrologic and sulfur isotopic studies have been carried out on drill core samples from a roll-type uranium deposit in the mid-Tertiary Catahoula Tuff, Webb County, south Texas. Epigenetic iron disulfide minerals formed in two distinct stages. The first stage involved sulfidization of the host rock by sulfide (H 2 S, HS-)-bearing solutions that emanated from a fault about 1.5 km downdip from and s
Authors
Martin B. Goldhaber, Richard L. Reynolds, Robert O. Rye
Paleomagnetic results from the Lassiter Coast, Antarctica, and a test for oroclinal bending of the Antarctic Peninsula
Paleomagnetic results from 17 magnetically stable units of Upper Cretaceous (‘Andean’) plutons and dikes of the Lassiter Coast, on the southern Antarctic Peninsula, define a mean paleomagnetic pole at 87°S, 131°W (α95 = 11.5°). This indicates that little latitudinal movement of the southern Antarctic Peninsula has occurred during the past 100 m.y. All magnetically stable intrusives are normally po
Authors
Karl S. Kellogg, Richard L. Reynolds
Factors contributing to the formation of ferromanganese nodules in Oneida Lake, New York
Oneida Lake is a large, shallow, eutrophic lake situated in the Ontario lowlands of central New York State. It contains the most concentrated deposit of freshwater ferromanganese nodules (in terms of amount per unit area) yet reported in the literature. The mineralogy and bulk chemistry of these saucer-shaped nodules are similar to the mineralogy and bulk chemistry of deep-sea ferromanganese nodu
Authors
Walter E. Dean, Swapan Ghosh
Paleomagnetism of welded tuffs of the Yellowstone group
Two of the three ash flow tuffs of the Yellowstone Group are stably magnetized throughout their extent: the Lava Creek tuff (0.60 m.y.) in a normal direction and the Mesa Falls tuff (1.22 m.y.) in a reversed direction. In contrast, much of the Huckleberry Ridge tuff, which was erupted during a polarity transition or field excursion 1.92 m.y. ago and initially magnetized in an intermediate directio
Authors
Richard L. Reynolds
Natural hazards in mountain Colorado
Interdisciplinary field studies and remote sensing techniques were used to delineate mountain areas in Colorado subject to such natural hazards as snow avalanches, mudflows, rockfalls, and landslides. The old mining townsite of Ophir in the northwestern San Juan Mountains was used as a case study. Its serious snow avalanche hazard has been made even more critical with prospects of new housing deve
Authors
Jack D. Ives, Authur I. Mears, Paul E. Carrara, Michael J. Bovis
Bog stratigraphy, radiocarbon dates, and Pinedale to Holocene glacial history in the Front Range, Colorado
Radiocarbon dates and stratigraphic cores from bogs, kettle ponds, and former ice-marginal lakes on the east and west sides of the Front Range, Colo., between lat 40°00' and 40°24' N. suggest that (1) valley glaciers of Pinedale age began to recede from their terminal positions between about 14,600 and 13,000 yr ago, (2) revegetation of glaciated areas at altitudes of 2,600-2,900 m (8,600-9,500 ft
Authors
Richard F. Madole