Publications
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Evidence of repeated wildfires prior to human occupation on San Nicolas Island, California
Understanding how early humans on the California Channel Islands might have changed local fire regimes requires a baseline knowledge of the frequency of natural wildfires on the islands prior to human occupation. A sedimentary sequence that was recently discovered in a small canyon on San Nicolas Island contains evidence of at least 24 burn events that date to between ∼37 and 25 ka (thousands of c
Authors
Jeffrey S. Pigati, John P. McGeehin, Gary L. Skipp, Daniel R. Muhs
Karst in the United States: A digital map compilation and database
This report describes new digital maps delineating areas of the United States, including Puerto Rico and the U.S. Virgin Islands, having karst or the potential for development of karst and pseudokarst. These maps show areas underlain by soluble rocks and also by volcanic rocks, sedimentary deposits, and permafrost that have potential for karst or pseudokarst development. All 50 States contain rock
Authors
David J. Weary, Daniel H. Doctor
Key subsurface data help to refine Trinity aquifer hydrostratigraphic units, south-central Texas
The geologic framework and hydrologic characteristics of aquifers are important components for studying the nation’s subsurface heterogeneity and predicting its hydraulic budgets. Detailed study of an aquifer’s subsurface hydrostratigraphy is needed to understand both its geologic and hydrologic frameworks. Surface hydrostratigraphic mapping can also help characterize the spatial distribution and
Authors
Charles D. Blome, Allan K. Clark
Paleoseismology of the Southern Section of the Black Mountains and Southern Death Valley Fault Zones, Death Valley, United States
The Death Valley Fault System (DVFS) is part of the southern Walker Lane–eastern California shear zone. The normal Black Mountains Fault Zone (BMFZ) and the right-lateral Southern Death Valley Fault Zone (SDVFZ) are two components of the DVFS. Estimates of late Pleistocene-Holocene slip rates and recurrence intervals for these two fault zones are uncertain owing to poor relative age control. The B
Authors
Marsha S. Sohn, Jeffrey R. Knott, Shannon Mahan
A geochronologic framework for the Ziegler Reservoir fossil site, Snowmass Village, Colorado
The Ziegler Reservoir fossil site near Snowmass Village, Colorado, provides a unique opportunity to reconstruct high-altitude paleoenvironmental conditions in the Rocky Mountains during the last interglacial period. We used four different techniques to establish a chronological framework for the site. Radiocarbon dating of lake organics, bone collagen, and shell carbonate, and in situ cosmogenic 1
Authors
Shannon Mahan, Harrison J. Gray, Jeffrey S. Pigati, Jim Wilson, Nathaniel A. Lifton, James B. Paces, Maarten Blaauw
The notion of climate-driven strath-terrace production assessed via dissimilar stream-process response to late Quaternary climate
Previous research results from the Gabilan Mesa are combined with new optically stimulated luminescence (OSL) age estimates and sedimentological analyses with the aim of identifying factors that inhibit climate-driven strath-terrace production, and factors that make possible strath-terrace production independent of climate forcing. The factors are revealed by comparing the morphostratigraphy and O
Authors
Antonio F. García, Shannon Mahan
U.S. Geological Survey Science for the Wyoming Landscape Conservation Initiative: 2012 annual report
Southwest Wyoming contains abundant energy resources, wildlife, habitat, open spaces, and outdoor recreational opportunities. Although energy exploration and development have been taking place in the region since the late 1800s, the pace of development for fossil fuels and renewable energy increased significantly in the early 2000s. This and the associated urban and exurban development are leading
Authors
Zachary H. Bowen, Cameron L. Aldridge, Patrick J. Anderson, Timothy J. Assal, Carleton R. Bern, Laura Biewick, Gregory K. Boughton, Natasha B. Carr, Anna D. Chalfoun, Geneva W. Chong, Melanie L. Clark, Bradford C. Fedy, Katharine Foster, Steven L. Garman, Steve Germaine, Matthew G. Hethcoat, Collin G. Homer, Matthew J. Kauffman, Douglas Keinath, Natalie Latysh, Daniel J. Manier, Robert R. McDougal, Cynthia P. Melcher, Kirk A. Miller, Jessica Montag, Christopher J. Potter, Spencer Schell, Sarah L. Shafer, David B. Smith, Michael J. Sweat, Anna B. Wilson
Carnivore distributions across chaparral habitats exposed to wildfire and rural housing in southern California
Chaparral and coastal sage scrub habitats in southern California support biologically diverse plant and animal communities. However, native plant and animal species within these shrubland systems are increasingly exposed to human-caused wildfires and an expansion of the human–wildland interface. Few data exist to evaluate the effects of fire and anthropogenic pressures on plant and animal communit
Authors
P.A. Schuette, J.E. Diffendorfer, D.H. Deutschman, S. Tremor, W. Spencer
Replacement cost valuation of Northern Pintail (Anas acuta) subsistence harvest in Arctic and sub-Arctic North America
Migratory species provide economically beneficial ecosystem services to people throughout their range, yet often, information is lacking about the magnitude and spatial distribution of these benefits at regional scales. We conducted a case study for Northern Pintails (hereafter pintail) in which we quantified regional and sub-regional economic values of subsistence harvest to indigenous communitie
Authors
Joshua H. Goldstein, Wayne E. Thogmartin, Kenneth J. Bagstad, James A. Dubovsky, Brady J. Mattsson, Darius J. Semmens, Laura López-Hoffman, James E. Diffendorfer
Mapping mountain pine beetle mortality through growth trend analysis of time-series landsat data
Disturbances are key processes in the carbon cycle of forests and other ecosystems. In recent decades, mountain pine beetle (MPB; Dendroctonus ponderosae) outbreaks have become more frequent and extensive in western North America. Remote sensing has the ability to fill the data gaps of long-term infestation monitoring, but the elimination of observational noise and attributing changes quantitative
Authors
Lu Liang, Yanlei Chen, Todd Hawbaker, Zhi-Liang Zhu, Peng Gong
Modeling the influence of organic acids on soil weathering
Biological inputs and organic matter cycling have long been regarded as important factors in the physical and chemical development of soils. In particular, the extent to which low molecular weight organic acids, such as oxalate, influence geochemical reactions has been widely studied. Although the effects of organic acids are diverse, there is strong evidence that organic acids accelerate the diss
Authors
Corey R. Lawrence, Jennifer W. Harden, Kate Maher
Validating a method for transferring social values of ecosystem services between public lands in the Rocky Mountain region
With growing pressures on ecosystem services, social values attributed to them are increasingly important to land management decisions. Social values, defined here as perceived values the public ascribes to ecosystem services, particularly cultural services, are generally not accounted for through economic markets or considered alongside economic and ecological values in ecosystem service assessme
Authors
Benson C. Sherrouse, Darius J. Semmens