Publications

Over a span of 50 years, native Californian Donald Lee Johnson made a number of memorable contributions to our understanding of the California Channel Islands. Among these are (1) recognizing that carbonate dunes, often cemented into eolianite and derived from offshore shelf sediments during lowered sea level, are markers of glacial periods on the Channel Islands; (2) identifying beach...

Knowing depositional ages of alluvial fans is essential for many tectonic, paleoclimatic, and geomorphic studies in arid environments. The use of U–Pb dating on secondary silica to establish the age of Neogene-Quaternary clastic sediments was tested on samples of authigenic and detrital opal and chalcedony from depths of ∼25 to 53 m in boreholes at Midway Valley, Nevada. Dating of...

The presence of ca. 1.63 Ga monzogranite (the “white quartz monzonite”) in the southern Sierra Madre, southeastern Wyoming, is anomalous given its distance from the nearest documented plutons of similar age (central Colorado) and the nearest contemporaneous tectonic margin (New Mexico). It is located immediately south of the Cheyenne belt—a ca. 1.75 Ga Archean-Proterozoic tectonic suture...

Geologic mapping, age determinations, and geochemistry of rocks exposed in the Abiquiu area of the Abiquiu embayment of the Rio Grande rift, north-central New Mexico, provide data to determine fault-slip and incision rates. Vertical-slip rates for faults in the area range from 16 m/m.y. to 42 m/m.y., and generally appear to decrease from the eastern edge of the Colorado Plateau to the...

The Arctic climate is changing, inducing accelerating retreat of ice-rich permafrost coastal bluffs. Along Alaska’s Beaufort Sea coast, erosion rates have increased roughly threefold from 6.8 to 19 m yr−1 since 1955 while the sea ice-free season has increased roughly twofold from 45 to 100 days since 1979. We develop a numerical model of bluff retreat to assess the relative roles of the...

Executive Summary Core Science Systems is a new mission of the U.S. Geological Survey (USGS) that resulted from the 2007 Science Strategy, “Facing Tomorrow’s Challenges: U.S. Geological Survey Science in the Decade 2007–2017.” This report describes the Core Science Systems vision and outlines a strategy to facilitate integrated characterization and understanding of the complex Earth...

Cambrian and Ordovician shelf, platform, and basin rocks are present in Sonora, Mexico, and southern Arizona and were deposited on the southwestern continental margin of North America (Laurentia). Cambrian and Ordovician rocks in Sonora, Mexico, are mostly exposed in scattered outcrops in the northern half of the state. Their discontinuous nature results from extensive Quaternary and...

The Sunshine Valley-Costilla Plain, a structural subbasin of the greater San Luis Basin of the northern Rio Grande rift, is bounded to the north and south by the San Luis Hills and the Red River fault zone, respectively. Surficial mapping, neotectonic investigations, geochronology, and geophysics demonstrate that the structural, volcanic, and geomorphic evolution of the basin involves...

Streamflow information is critical for addressing any number of hydrologic problems. Often, streamflow information is needed at locations that are ungauged and, therefore, have no observations on which to base water management decisions. Furthermore, there has been increasing need for daily streamflow time series to manage rivers for both human and ecological functions. To facilitate...

The Paleogene sedimentary deposits of the Colorado Headwaters Basin provide a detailed proxy record of regional deformation and basin subsidence during the Laramide orogeny in north-central Colorado and southern Wyoming. This field trip presents extensive evidence from sedimentology, stratigraphy, structure, palynology, and isotope geochronology that shows a complex history that is...

Climate Change in the Northwest: Implications for Our Landscapes, Waters, and Communities is aimed at assessing the state of knowledge about key climate impacts and consequences to various sectors and communities in the northwest United States. It draws on a wealth of peer-reviewed literature, earlier state-level assessment reports conducted for Washington (2009) and Oregon (2010), as...

No abstract available.