In the mid‐1980s, advances in understanding the mechanics of the fold‐and‐thrust belts that flank many collisional mountain ranges set the stage for a fundamental change in our appreciation of the role of erosion in the tectonic evolution of mountain ranges. A combination of sandbox experiments, analytical treatments of stress state and field observations showed that fold‐and‐thrust belts form ...

Meta-ultramafi c rocks occur as small (2 to 100 m long), podiform bodies in all three major Precambrian rock suites of the Tobacco Root Mountains of southwest Montana. Most samples consist of a randomly oriented, coarse-grained assemblage of orthopyroxene, olivine, and magnesiohornblende ± spinel, partially replaced by a fi ne-grained assemblage that may include anthophyllite, talc, cummingtoni...

The concept whereby heat is recovered from a geothermal reservoir by replacing the native aqueous phase with essentially pure high-pressure carbon dioxide as the working fluid is referred to as an Enhanced Geothermal System with CO2 (EGSCO2). The concept has yet to be tested in the field, and the chemical consequences, both within the reservoir itself, and at its periphery, are not fully unders...

Radon gas is the largest natural source of human exposure to ionizing radiation and most of that exposure occurs in indoor air. Bedrock geology is an important factor in radon hazard evaluation of an area. The presence of rock types usually rich in uranium can be considered an indication of a potential radon hazard. In this study the average Ra activity concentration of the main rock types (ort...

Bastnaesite, a rare-earth fluocarbonate, was found in the Mountain Pass district in April 1949. Subsequent geologic mapping has shown that rare-earth mineral deposits occur in a belt about 6 miles long and iy2 miles wide. One of the deposits, the Sulphide Queen carbonate body, is the greatest concentration of rare-earth minerals now known in the world. The Mountain Pass district is in a block o...