Publications

A meaningful interpretation of geophysical measurements requires an assessment of the space of models that are consistent with the data, rather than just a single, ‘best’ model which does not convey information about parameter uncertainty. For this purpose, a trans-dimensional Bayesian Markov chain Monte Carlo (MCMC) algorithm is developed for assessing frequencydomain electromagnetic (FDEM) data

Drainage channels are among the most conspicuous surficial features of deserts, but little quantitative analysis of their influence on plant distributions is available. We analysed the effects of desert stream channels (‘washes’) on Larrea tridentata and Ambrosia dumosa density and cover on an alluvial piedmont in the Mojave Desert, based on a spatial analysis of transect data encompassing a total

Permafrost contains an estimated 1672 Pg carbon (C), an amount roughly equivalent to the total currently contained within land plants and the atmosphere1,2,3. This reservoir of C is vulnerable to decomposition as rising global temperatures cause the permafrost to thaw2. During thaw, trapped organic matter may become more accessible for microbial degradation and result in greenhouse gas emissions4,

Paramagnetic manganese can be employed as a calcium surrogate to sensitize the magnetic resonance imaging (MRI) technique to the processing of calcium during the bone formation process. At low doses, after just 48h of exposure, osteoblasts take up sufficient quantities of manganese to cause marked reductions in the water proton T1 values compared with untreated cells. After just 24h of exposure, 2

Geologic mapping and analysis of ASTER remote sensing data were used to define the effects of a large hydrothermal system in the 12–18 by 22 km Caetano caldera. The caldera formed at ~33.8Ma during eruption of >1100km3 of the rhyolitic Caetano Tuff that left a 1 km deep basin which was partly filled by a lake. Magma resurgence resulted in shallow(<1 km) emplacement of the Redrock Canyon granite po

The provenance and stratigraphic architecture of basin-filling Miocene sediments around the Gold Butte area, southern Nevada, and adjacent highlands record the erosion of fault blocks that progressively tilted during extension. This study focuses especially on upper Miocene correlatives of the red sandstone unit and the Muddy Creek Formation that were deposited during waning stages of extension. U

[1] A robust database of paleomagnetic (PM) and archeomagnetic (AM) data for western North America covering the past 4 millennia is assembled from three data sets: (1) published PM data for dated lava flows, (2) recently published AM data generated by R. L. DuBois, and (3) published AM data generated by J. L. Eighmy. Chronologic information for the AM data sets has been reassessed, and the data po

Unfavorable groundwater conditions are often the determining factor in triggering landslides. Whereas regional hydrogeology typically determines overall groundwater conditions, surficial rainfall infiltration into slopes also drives potential instability.

Congress enacted the Defense Production Act in 1950 to provide funding and support for the exploration and development of critical mineral resources. From 1950 to 1974, three Department of the Interior agencies carried out this mission. Contracts with mine owners provided financial assistance for mineral exploration on a joint-participation basis. These contracts are documented in more than 5,000

Minerals in the environment and products manufactured from mineral materials are all around us and we use and come into contact with them every day. They impact our way of life and the health of all that lives. Minerals are critical to the Nation's economy and knowing where future mineral resources will come from is important for sustaining the Nation's economy and national security. The U.S. G

The rare earth elements (REE) are fifteen elements with atomic numbers 57 through 71, from lanthanum to lutetium ('lanthanides'), plus yttrium (39), which is chemically similar to the lanthanide elements and thus typically included with the rare earth elements. Although industrial demand for these elements is relatively small in tonnage terms, they are essential for a diverse and expanding array o