Publications
Publications from the staff of the Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 2354
The past as prelude to the future for understanding 21st-century climate effects on Rocky Mountain Trout
Bioclimatic models predict large reductions in native trout across the Rocky Mountains in the 21st century but lack details about how changes will occur. Through five case histories across the region, we explore how a changing climate has been affecting streams and the potential consequences for trout. Monitoring records show trends in temperature and hydrographs consistent with a warming climate
Authors
Daniel J. Isaak, Clint C. Muhlfeld, Andrew S. Todd, Robert Al-chokhachy, James Roberts, Jeffrey L. Kershner, Kurt D. Fausch, Steven W. Hostetler
Tectonic influences on the preservation of marine terraces: Old and new evidence from Santa Catalina Island, California
The California Channel Islands contain some of the best geologic records of past climate and sea-level changes, recorded in uplifted, fossil-bearing marine terrace deposits. Among the eight California Channel Islands and the nearby Palos Verdes Hills, only Santa Catalina Island does not exhibit prominent emergent marine terraces, though the same terrace-forming processes that acted on the other Ch
Authors
R. Randall Schumann, Scott A. Minor, Daniel R. Muhs, Lindsey T. Groves, John P. McGeehin
Lower-crustal xenoliths from Jurassic kimberlite diatremes, upper Michigan (USA): Evidence for Proterozoic orogenesis and plume magmatism in the lower crust of the southern Superior Province
Jurassic kimberlites in the southern Superior Province in northern Michigan contain a variety of possible lower-crustal xenoliths, including mafic garnet granulites, rare garnet-free granulites, amphibolites and eclogites. Whole-rock major-element data for the granulites suggest affinities with tholeiitic basalts. P–T estimates for granulites indicate peak temperatures of 690–730°C and pressures o
Authors
Robert E. Zartman, Pamela D. Kempton, James B. Paces, Hilary Downes, Ian S. Williams, Gábor Dobosi, Kiyoto Futa
Slope-Area Computation Program Graphical User Interface 1.0—A Preprocessing and Postprocessing Tool for Estimating Peak Flood Discharge Using the Slope-Area Method
The slope-area method is a technique for estimating the peak discharge of a flood after the water has receded (Dalrymple and Benson, 1967). This type of discharge estimate is called an “indirect measurement” because it relies on evidence left behind by the flood, such as high-water marks (HWMs) on trees or buildings. These indicators of flood stage are combined with measurements of the cross-secti
Authors
D. Nathan Bradley
Digital geologic map of the Redding 1° x 2° quadrangle, Shasta, Tehama, Humboldt, and Trinity Counties, California
The Redding 1° x 2° quadrangle in northwestern California transects the Franciscan Complex and southern Klamath Mountains province as well as parts of the Great Valley Complex, northern Great Valley, and southernmost Cascades volcanic province. The tectonostratigraphic terranes of the Klamath province represent slices of oceanic crust, island arcs, and overlying sediment that range largely from Pa
Authors
Luis A. Fraticelli, John P. Albers, William P. Irwin, Milton C. Jr. Blake, Carl M. Wentworth
MiniSipper: A new in situ water sampler for high-resolution, long-duration acid mine drainage monitoring
Abandoned hard-rock mines can be a significant source of acid mine drainage (AMD) and toxic metal pollution to watersheds. In Colorado, USA, abandoned mines are often located in remote, high elevation areas that are snowbound for 7–8 months of the year. The difficulty in accessing these remote sites, especially during winter, creates challenging water sampling problems and major hydrologic and tox
Authors
Thomas P. Chapin, Andrew S. Todd
Using geochemistry to identify the source of groundwater to Montezuma Well, a natural spring in Central Arizona, USA: Part 2
Montezuma Well is a unique natural spring located in a sinkhole surrounded by travertine. Montezuma Well is managed by the National Park Service, and groundwater development in the area is a potential threat to the water source for Montezuma Well. This research was undertaken to better understand the sources of groundwater to Montezuma Well. Strontium isotopes (87Sr/86Sr) indicate that groundwater
Authors
Raymond H. Johnson, Ed DeWitt, Laurie Wirt, Andrew H. Manning, Andrew G. Hunt
Holocene diatom flora and climate history of Medicine Lake, Northern California, USA
A 226-cm-long sediment core spanning the past ~ 11,400 years was recovered from Medicine Lake, on the Modoc Plateau in northeastern California. Diatom assemblages provide a record of lake level that is driven by local and regional climate changes and changes in basin morphology due to the activity of Medicine Lake volcano. The diatom record indicates that throughout its history, Medicine Lake was
Authors
Scott W. Starratt
Constraining the location of the Archean--Proterozoic suture in the Great Basin based on magnetotelluric soundings
It is important to understand whether major mining districts in north-central Nevada are underlain by Archean crust, known to contain major orogenic gold deposits, or, alternatively, by accreted crust of the Paleoproterozoic Mojave province. Determining the location and orientation of the Archean-Proterozoic suture zone between the Archean crust and Mojave province is also critical because it may
Authors
Brian D. Rodriguez, Jay A. Sampson
Geophysical studies in the vicinity of Blue Mountain and Pumpernickel Valley near Winnemucca, north-central Nevada
From May 2008 to September 2009, the U.S. Geological Survey (USGS) collected data from more than 660 gravity stations, 100 line-km of truck-towed magnetometer traverses, and 260 physical-property sites in the vicinity of Blue Mountain and Pumpernickel Valley, northern Nevada (fig. 1). Gravity, magnetic, and physical-property data were collected to study regional crustal structures as an aid to und
Authors
David A. Ponce
Polyplacophora (Mollusca) from the San Diego Formation: A remarkable assemblage of fossil chitons from the Pliocene of southern Califoria
A rich chiton assemblage consisting of more than 15,000 valves (shell plates) was collected by George P. Kanakoff (1897–1973) from Pliocene exposures of the San Diego Formation just north of the U.S./Mexican border. The assemblage includes 16 extant species, three extinct species (Callistochiton sphaerae n. sp., Lepidozona kanakoffi n. sp., and Amicula solivaga n. sp.), and three indeterminate spe
Authors
Michael J. Vendrasco, Douglas J. Eernisse, Charles L. Powell, Christine Z. Fernandez
Evolution of 3-D geologic framework modeling and its application to groundwater flow studies
In this Fact Sheet, the authors discuss the evolution of project 3-D subsurface framework modeling, research in hydrostratigraphy and airborne geophysics, and methodologies used to link geologic and groundwater flow models.
Authors
Charles D. Blome, David V. Smith