bluuebunny/crossref_metadata_2025 huggingface dataset:
An econometric analysis of regional adoption patterns of Bt maize in Germany
Authors: Consmüller Nicola , Beckmann Volker , Petrick Martin
Published: April 2010

In this study, our goal is to identify and explain the underlying factors that drive regional adoption of Bt maize MON810 in Germany. Since regional differences cannot be explained by the occurrence of the target pest alone, we assume that under the given regulatory framework for genetically modified (GM) crop production in Germany, farm structures as well as the sociopolitical environment have also influenced regional adoption rates during the past years. Following a description of the relevant legal and economic framework in Germany, we develop theoretical hypotheses for regional variation in Bt maize adoption and test them econometrically with unique data at the federal state (Laender) and county (Landkreis) level. According to our analysis at the federal state level, the maize acreage per farm is the main driver of Bt maize adoption. In addition, there are signs that public opposition to GM cultivation as measured by membership in the German Friends of the Earth association significantly dampens GM cultivation. At the level of Brandenburg counties, the regional infestation frequency of the European Corn Borer, the target pest of Bt‐Maize, is the major determinant of adoption. Although Bt maize is a scale‐neutral technology for controlling damages caused by the Corn Borer, additional fixed costs due to regulation make the technology scale dependent.
Getting implicit shadow prices right for the estimation of the Malmquist index: the case of agricultural total factor productivity in developing countries
Authors: Nin‐Pratt Alejandro , Yu Bingxin
Published: April 2010

The Malmquist index has become extensively used in international comparisons of agricultural productivity since it does not require prices for its estimation, which are normally not available. However, the data envelopment analysis (DEA) approach used to estimate this index still uses implicit price information. This entails potential problems because these methods are susceptible to the effect of data noise, and shadow prices can prove to be inconsistent with prior knowledge on cost shares. In this article, we analyze implicit input shadow shares used in the DEA approach to estimate agricultural productivity using the Malmquist index for 63 developing countries. We then set bounds to the implicit input shares by introducing information on their likely value and compare constrained and unconstrained input shares. We conclude that the incidence of zero shadow prices justifies the introduction of constraints in the estimation of the Malmquist index. The article also presents detailed results of TFP growth in developing countries using constrained shadow shares for their estimation. We find that agricultural TFP has been growing steadily in the past 20 years even if countries like China, Brazil, and India are not considered. Remarkably, we find a clear improvement in the performance of Sub‐Saharan Africa since the mid 1980s.
Does heterogeneity in goals and preferences affect efficiency? A case study of farm households in northern Nigeria
Authors: Berkhout Ezra D. , Schipper Robert A. , Kuyvenhoven Arie , Coulibaly Ousmane
Published: April 2010

Household characteristics are commonly used to explain variation in smallholder efficiency levels. The underlying assumption is that differences in intended behavior are well described by such variables, while there is no a priori reason that this is the case. Moreover, heterogeneity in farmer goals and preferences, in relation to the role of the farm enterprise, are not well documented in developing countries. This article makes a contribution to fill this gap, by empirically determining heterogeneity in farmer goals and attitudes in Nigeria through a pair‐wise ranking, supplemented with Likert scales. Factor analysis is used to reduce these data into behavioral factors. We estimate technical and allocative efficiency levels and analyze how these are related to farm characteristics and the identified behavioral factors. The models in which both intended behavior and farmer characteristics are included give a significantly better fit over models in which only household characteristics are included. These regression results suggest that the socioeconomic environment affects efficiency levels both directly and indirectly, through changes in goals and attitudes.
Productivity growth and the effects of R&D in African agriculture
Authors: Alene Arega D.
Published: April 2010

This article measures and compares total factor productivity growth in African agriculture under contemporaneous and sequential technology frontiers over the period 1970–2004. The sources of productivity growth are examined using a fixed‐effects regression model and a polynomial distributed lag structure for agricultural R&D expenditures. While conventional estimates show an average productivity growth rate of only 0.3% per year, the improved measures under sequential technology show that African agricultural productivity grew at a higher rate of 1.8% per year. Technical progress, rather than efficiency change, was the principal source of productivity growth. Agricultural R&D, weather, and trade reforms turned out to have significant effects on productivity in African agriculture. With a rate of return of 33% per year, R&D is shown to be a socially profitable investment in African agriculture. While a strong R&D expenditure growth of about 2% per year in the 1970s led to strong productivity growth after the mid 1980s, stagnation of R&D expenditure in the 1980s and early 1990s led to slower productivity growth in the 2000s. Consistent with recent economic recovery in Africa evidenced by stronger agricultural GDP growth rates, results showed that policy reforms as well as improved weather contributed to the recovery of agricultural productivity after the mid 1980s.
Influence of aquatic plant‐specific habitat on an assemblage of small neotropical floodplain fishes
Authors: Dibble E. D. , Pelicice F. M.
Published: April 2010

Dibble ED, Pelicice FM. Influence of aquatic plant‐specific habitat on an assemblage of small neotropical floodplain fishes. Ecology of Freshwater Fish 2010: 19: 381–389. © 2010 John Wiley & Sons A/S

Abstract –  This study investigated the effects of plant‐specific habitat on the distribution of young and small adult fishes in lagoons of the Upper Paraná River floodplain, Brazil. We compared fish catch per unit effort (CPUE) and species richness and used an indirect gradient analysis to investigate fish‐plant relationships within three aquatic macrophytes beds (Cabomba furcata, Eichhornia azurea, Nymphaea amazonum), and explored microhabitat influence (indexed by eight variables related to physical structure and water quality) on the structure of fish assemblages. Rarefaction analysis was used to compare fish species richness among the vegetated habitats. We captured a total of 1599 fish constituting 23 species, 7 families and 3 orders. Fish CPUE and species richness increased relative to microhabitat structure innate to the macrophytes; higher CPUE and richness were observed in C. furcata beds, a submerged aquatic macrophyte with finely dissected leaves. On the contrary, N. amazonum, a species that provides low microhabitat complexity, harbored fewer individual fish and number of species. Reproduction dynamics, hydrology and the amount of available plant‐generated habitat structure (surface effect) contributed to the disproportionally high number of individuals captured during the dry season. Our data suggest that the microhabitat physical structure (e.g., edge distance, stem density and patch size) provided by macrophyte beds in the lagoons of the Upper Paraná River may play a more important role than physicochemistry (e.g., oxygen, temperature and pH) at mediating distribution patterns of small‐sized fishes.
ORIGINAL ARTICLE: Leptin associations with age, weight, and sex among chimpanzees (Pan troglodytes)
Authors: Bribiescas Richard G. , Anestis Stephanie F.
Published: April 2010

Background  Leptin is a hormone secreted primarily by adipocytes, a lipostatic signal to the hypothalamus, and is often correlated with adiposity. Associations between leptin, age, and development are unknown in human’s closest evolutionary relative, the common chimpanzee (Pan troglodytes).

Methods  Serum leptin was assessed cross sectionally in association with age, weight, and sex in healthy captive chimpanzee males (n = 47) and females (n = 49) to test hypotheses related to predicted differences in leptin levels with body mass, development, and sexual dimorphism.

Results  Leptin increased with age and weight among females, but not in males. Leptin was overall higher in females compared to males.

Conclusions  Sex differences in leptin were most evident during adolescence and adulthood, despite similar increases in weight in both sexes indicating that sexual maturation is a key divergence point for differential somatic investment in adiposity and leptin levels between male and female chimpanzees.
Post‐varicella thrombocytopenic purpura
Authors: Amir Achiya , Gilad Oded , Yacobovich Joanne , Scheuerman Oded , Tamary Hannah , Garty Ben‐Zion
Published: April 2010

Aims:  The aim of the study was to characterize the clinical course of post‐varicella idiopathic thrombocytopenic purpura (ITP) and to asses the risk of acquiring ITP after varicella infection.

Methods:  A retrospective study of all children diagnosed with ITP in a tertiary medical centre during 1998–2008. Findings were compared with the Intercontinental Childhood ITP Study Group database. The risk of acquiring ITP after a varicella infection was assessed.

Results:  Ten children were diagnosed with post‐varicella ITP. The incidence of post‐varicella ITP was 1.9% amongst children diagnosed with ITP and 1.1% amongst children hospitalized for varicella. ITP was diagnosed, on average, 8.5 days after the onset of the varicella rash. The female‐to‐male ratio was 1:1.5. The average minimal platelet count was 9.5 × 109 platelets/L. Post‐varicella ITP had an acute course in 80% of cases and a chronic course in the remaining 20%. Bleeding episodes occurred in three patients. During the follow‐up period, 11 patients with previously diagnosed ITP developed varicella. The infection had no apparent affect on the platelet count of the children with acute ITP, but caused a relapse in 71% of the patients with chronic ITP.

Conclusions: Post‐varicella ITP has similar clinical features and course to non‐varicella associated ITP. The calculated risk of ITP as a complication of varicella infections is approximately 1:25 000.
Taxonomic identification of Amazonian tree crowns from aerial photography
Authors: González‐Orozco Carlos E. , Mulligan Mark , Trichon Valérie , Jarvis Andrew
Published: April 2010

Question: To what extent can aerial photography be used for taxonomic identification of Amazonian tree crowns?

Objective: To investigate whether a combination of dichotomous keys and a web‐based interface is a suitable approach to identify tree crowns.

Location: The fieldwork was conducted at Tiputini Biodiversity Station located in the Amazon, eastern Ecuador.

Methods: High‐resolution imagery was taken from an airplane flying at a low altitude (600 m) above the ground. Imagery of the observable upper layer of the tree crowns was used for the analysis. Dichotomous identification keys for different types of crowns were produced and tested. The identification keys were designed to be web‐based interactive, using Google Earth as the main online platform. The taxa analysed were Iriartea, Astrocaryum, Inga, Parkia, Cecropia, Pourouma, Guarea, Otoba, Lauraceae and Pouteria.

Results: This paper demonstrates that a combination of photo‐imagery, dichotomous keys and a web‐based interface can be useful for the taxonomic identification of Amazonian trees based on their crown characteristics. The keys tested with an overall identification accuracy of over 50% for five of the ten taxa with three of them showing accuracy greater than 70% (Iriartea, Astrocaryum and Cecropia).

Conclusions: The application of dichotomous keys and a web‐based interface provides a new methodological approach for taxonomic identification of various Amazonian tree crowns. Overall, the study showed that crowns with a medium‐rough texture are less reliably identified than crowns with smoother or well‐defined surfaces.
In‐Well Degassing Issues for Measurements of Dissolved Gases in Groundwater
Authors: Roy J.W. , Ryan M.C.
Published: April 2010

Measurement of dissolved gases in groundwater is becoming increasingly common and important. Many of these measurements involve monitoring or sampling within wells or from water pumped from wells. We used total dissolved gas pressure (TDGP) sensors placed in the screened section of various wells (4 to 72 m deep) to assess the dissolved gas conditions for open wells compared to the conditions when sealed (i.e., isolated from the atmosphere) with a hydraulic packer (one well) or when pumped. When the packer was installed (non‐pumping conditions), TDGP rose from <1.7 to >3.1 atm (<172 to >314 kPa), with declines noted when the packer was removed or deflated. While pumping, TDGP measured in many of the wells rose to substantially higher levels, up to 4.0 atm (408 kPa) in one case. Thus, when groundwater is gas charged, the background aquifer TDGP, and likewise the dissolved gas concentrations, may be substantially higher than initially measured in open wells, indicating significant in‐well degassing. This raises concerns about past and current methods of measuring the dissolved gases in groundwater. Additional procedures that may be required to obtain representative measurements from wells include (1) installing in‐well hydraulic packers to seal the well, or (2) pumping to bring in fresh groundwater. However, observed transient decreased TDGPs during pumping, believed to result from gas bubble formation induced by drawdown in the well below a critical pressure (relative to TDGP), may disrupt the measurements made during or after pumping. Thus, monitoring TDGP while pumping gas‐charged wells is recommended.
Efficacy of dye disappearance test and tear meniscus height in diagnosis and postoperative assessment of nasolacrimal duct obstruction
Authors: Roh Joon Ho , Chi Mi Jung
Published: April 2010

Objective:  To evaluate the efficacy of the fluorescein dye disappearance test (FDDT) and measurement of tear meniscus height (TMH) in the diagnosis and postoperative assessment of nasolacrimal duct obstruction (NLDO).

Methods:  The study group included 42 eyes of 42 patients who had a diagnosis of primary acquired nasolacrimal duct obstruction (PANDO) or functional nasolacrimal duct obstruction (FNDO) and underwent endoscopic transnasal dacryocystorhinostomy. The control group included 38 eyes of 38 people without tearing. The values of the FDDT, TMH and tearing symptom score (TSS), which was evaluated in five levels based on patients’ history taking, were measured before surgery, and 1 day, 2 weeks, 1, 3 and 6 months after surgery. The values of the FDDT, TMH and TSS in the study group were compared with those of the control group.

Results:  The preoperative values of the FDDT, TMH and TSS were 0.7 ± 0.4, 0.22 ± 0.08 mm and 1.6, respectively, in the control group and 3.0 ± 0.8, 0.53 ± 0.15 mm and 4.4, respectively, in the study group. These differences were statistically significant. Also, at each follow‐up, the postoperative values of the FDDT and TMH decreased significantly compared to their preoperative values in the study group. The postoperative TSS decreased significantly compared to the preoperative values at each follow‐up except at postoperative 1‐day follow‐up. There were no significant differences in the preoperative values of the FDDT, TMH and TSS between the types of NLDO. The TSS had positive correlations with the FDDT and TMH before and after surgery.

Conclusion:  These results suggest that the FDDT and TMH measurement might be effective in the diagnosis and postoperative assessment of NLDO.
The Relation between Analysts' Forecasts of Long‐Term Earnings Growth and Stock Price Performance Following Equity Offerings*
Authors: DECHOW PATRICIA M. , HUTTON AMY P. , SLOAN RICHARD G.
Published: April 2010

In this paper we evaluate the role of sell‐side analysts' long‐term earnings growth forecasts in the pricing of common equity offerings. We find that, in general, sell‐side analysts' long‐term growth forecasts are systematically overly optimistic around equity offerings and that analysts employed by the lead managers of the offerings make the most optimistic growth forecasts. In additional, we find a positive relation between the fees paid to the affiliated analysts' employers and the level of the affiliated analysts' growth forecasts. We also document that the post‐offering underperformance is most pronounced for firms with the highest growth forecasts made by affiliated analysts. Finally, we demonstrate that the post‐offering underperformance disappears once we control for the overoptimism in earnings growth expectations. Thus, the evidence presented in this paper is consistent with the “equity issue puzzle” arising from overly optimistic earnings growth expectations held at the time of the offerings.
Stochastic Finite-Time Stabilization for Uncertain Jump Systems via State Feedback
Authors: He Shuping , Liu Fei
Published: April 2010

The stochastic finite-time stabilization problem is considered for a class of linear uncertain Markov jump systems that possess randomly jumping parameters. The transition of the jumping parameters is governed by a finite-state Markov process. By using the appropriate stochastic Lyapunov–Krasovskii functional approach, sufficient conditions are proposed for the design of stochastic finite-time stabilization controller. The stabilization criteria are formulated in the form of linear matrix inequalities and the designed finite-time stabilization controller is described as an optimization one. The designed finite-time stabilized controller makes the stochastic MJSs stochastic finite-time bounded and stochastic finite-time stabilizable for all admissible unknown external disturbances and uncertain parameters. Simulation results illustrate the effectiveness of the developed approaches.
Estimating Road Angles With the Knowledge of the Vehicle Yaw Angle
Authors: Hsu Ling-Yuan , Chen Tsung-Lin
Published: April 2010

This paper presents a method of estimating road angles using state observers and three types of sensors (lateral acceleration sensors, longitudinal velocity sensors, and suspension displacement sensors). The proposed method differs from those in most existing literature in three aspects. First, a “full-state” vehicle model is used to describe nonlinear vehicle dynamics on a sloped road. Second, “switching observer” techniques are used to suggest suitable sensors and to construct state observers. Lastly, the road angles are described by three Euler angles, and two of them are estimated simultaneously. The analysis indicates that (1) road angles affect vehicle dynamics through components of the gravitational force acting on the vehicle body. These gravitational forces can be correctly estimated with an estimation accuracy less than 7.5%, even when road angles vary with time. (2) Those road angles can be correctly estimated only when the vehicle yaw angle is known.
Repeatable Redundant Manipulator Control Using Nullspace Quasivelocities
Authors: Bowling Alan , Harmeyer Sean
Published: April 2010

This paper presents a repeatable control scheme for redundant manipulators. It is developed in terms of physically meaningful variables, a concept closely related to integrability and homogeneity. This approach sheds a different light on some well-known phenomena related to redundant manipulator control. The control is developed by determining enough physically meaningful variables to describe the manipulator’s motions in the task and nullspaces, in a manner that allows them to be controlled independently. These variables are then used to develop physically meaningful controller error signals. As a consequence, all configurations in the workspace are repeatable, except for those at, or very close, to a kinematic singularity. The approach is illustrated on a 6DOF planar manipulator.
Cystic Fibrosis Pigs Develop Lung Disease and Exhibit Defective Bacterial Eradication at Birth
Authors: Stoltz David A. , Meyerholz David K. , Pezzulo Alejandro A. , Ramachandran Shyam , Rogan Mark P. , Davis Greg J. , Hanfland Robert A. , Wohlford-Lenane Chris , Dohrn Cassie L. , Bartlett Jennifer A. , Nelson George A. , Chang Eugene H. , Taft Peter J. , Ludwig Paula S. , Estin Mira , Hornick Emma E. , Launspach Janice L. , Samuel Melissa , Rokhlina Tatiana , Karp Philip H. , Ostedgaard Lynda S. , Uc Aliye , Starner Timothy D. , Horswill Alexander R. , Brogden Kim A. , Prather Randall S. , Richter Sandra S. , Shilyansky Joel , McCray Paul B. , Zabner Joseph , Welsh Michael J.
Published: April 2010

The lungs of just-born piglets with cystic fibrosis fail to efficiently eliminate bacteria, suggesting that lung problems in cystic fibrosis patients may be secondary to impaired antibacterial defense mechanisms.
Universal Vaccines: Shifting to One for Many
Authors: Cassone Antonio , Rappuoli Rino
Published: April 2010

Human vaccines, with their exquisite antigenic specificity, have greatly helped to eliminate or dramatically abate the incidence of a number of historical and current plagues, from smallpox to bacterial meningitis. Nonetheless, as new infectious agents emerge and the number of vaccine-preventable diseases increases, the practice and benefits of single-pathogen- or disease-targeted vaccination may be put at risk by constraints of timely production, formulation complexity, and regulatory hurdles. During the last influenza pandemic, extraordinary efforts by vaccine producers and health authorities have had little or no influence on disease prevention or mitigation. Recent research demonstrating the possibility of protecting against all influenza A virus types or even phylogenetically distant pathogens with vaccines based on highly conserved peptide or saccharide sequences is changing our paradigm. “Universal vaccine” strategies could be particularly advantageous to address protection from antibiotic-resistant bacteria and fungi for which no vaccine is currently available.
Folds, floods, and fine wine
Authors: Pogue Kevin R.
Published: April 2010

The geomorphology, soils, and climate of Columbia Basin vineyards are the result of a complex and dynamic geologic history that includes the Earth's youngest flood basalts, an active fold belt, and repeated cataclysmic flooding. Miocene basalt of the Columbia River Basalt Group forms the bedrock for most vineyards. The basalt has been folded by north-south compression, creating the Yakima fold belt, a series of relatively tight anticlines separated by broad synclines. Topography related to these structures has strongly influenced the boundaries of many of the Columbia Basin's American Viticultural Areas (AVAs). Water gaps in the anticlinal ridges of the Yakima fold belt restrict cold air drainage from the broad synclinal basins where many vineyards are located, enhancing the development of temperature inversions and locally increasing diurnal temperature variations. Vineyards planted on the southern limbs of Yakima fold belt anticlines benefit from enhanced solar radiation and cold air drainage. Most Columbia Basin vineyards are planted in soils formed in eolian sediment that is primarily derived from the deposits of Pleistocene glacial outburst floods. The mineralogy of the eolian sediment differs substantially from the underlying basalt. Vineyard soil chemistry is thus more complex in areas where eolian sediment is comparatively thin and basalt regolith lies within the rooting zone.

The components of physical terroir that broadly characterize the Columbia Basin, such as those described above, vary substantially both between and within its AVAs. The vineyards visited on this field trip are representative of both their AVAs and the variability of terroir within the Columbia Basin.
A field guide to Newberry Volcano, Oregon
Authors: Jensen Robert A. , Donnelly-Nolan Julie M. , Mckay Daniele
Published: April 2010

Newberry Volcano is located in central Oregon at the intersection of the Cascade Range and the High Lava Plains. Its lavas range in age from ca. 0.5 Ma to late Holocene. Erupted products range in composition from basalt through rhyolite and cover ~3000 km2. The most recent caldera-forming eruption occurred ~80,000 years ago. This trip will highlight a revised understanding of the volcano's history based on new detailed geologic work. Stops will also focus on evidence for ice and flooding on the volcano, as well as new studies of Holocene mafic eruptions. Newberry is one of the most accessible U.S. volcanoes, and this trip will visit a range of lava types and compositions including tholeiitic and calc-alkaline basalt flows, cinder cones, and rhyolitic domes and tuffs. Stops will include early distal basalts as well as the youngest intracaldera obsidian flow.
Ice and water on Newberry Volcano, central Oregon
Authors: Donnelly-Nolan Julie M. , Jensen Robert A.
Published: April 2010

Newberry Volcano in central Oregon is dry over much of its vast area, except for the lakes in the caldera and the single creek that drains them. Despite the lack of obvious glacial striations and well-formed glacial moraines, evidence indicates that Newberry was glaciated. Meter-sized foreign blocks, commonly with smoothed shapes, are found on cinder cones as far as 7 km from the caldera rim. These cones also show evidence of shaping by flowing ice. In addition, multiple dry channels likely cut by glacial meltwater are common features of the eastern and western flanks of the volcano. On the older eastern flank of the volcano, a complex depositional and erosional history is recorded by lava flows, some of which flowed down channels, and interbedded sediments of probable glacial origin. Postglacial lava flows have subsequently filled some of the channels cut into the sediments. The evidence suggests that Newberry Volcano has been subjected to multiple glaciations.
The post-Mazama northwest rift zone eruption at Newberry Volcano, Oregon
Authors: Mckay Daniele , Donnelly-Nolan Julie M. , Jensen Robert A. , Champion Duane E.
Published: April 2010

The northwest rift zone (NWRZ) eruption took place at Newberry Volcano ~7000 years ago after the volcano was mantled by tephra from the catastrophic eruption that destroyed Mount Mazama and produced the Crater Lake caldera. The NWRZ eruption produced multiple lava flows from a variety of vents including cinder cones, spatter vents, and fissures, possibly in more than one episode. Eruptive behaviors ranged from energetic Strombolian, which produced significant tephra plumes, to low-energy Hawaiian-style. This paper summarizes and in part reinterprets what is known about the eruption and presents information from new and ongoing studies. Total distance spanned by the eruption is 32 km north-south. The northernmost flow of the NWRZ blocked the Deschutes River upstream from the city of Bend, Oregon, and changed the course of the river. Renewed mafic activity in the region, particularly eruptions such as the NWRZ with tephra plumes and multiple lava flows from many vents, would have significant impacts for the residents of Bend and other central Oregon communities.
After the disaster
Authors: Major Jon J. , Crisafulli Charlie M. , Frenzen Peter , Bishop John
Published: April 2010

The 1980 eruption of Mount St. Helens caused instantaneous landscape disturbance on a grand scale. On 18 May 1980, an ensemble of volcanic processes, including a debris avalanche, a directed pyroclastic density current, voluminous lahars, and widespread tephra fall, abruptly altered landscape hydrology and geomorphology, and created distinctive disturbance zones having varying impacts on regional biota. Response to the geological and ecological disturbances has been varied and complex. In general, eruption-induced alterations in landscape hydrology and geomorphology led to enhanced stormflow discharge and sediment transport. Although the hydrolog-ical response to landscape perturbation has diminished, enhanced sediment transport persists in some basins. In the nearly 30 years since the eruption, 350 million (metric) tons of suspended sediment has been delivered from the Toutle River watershed to the Cowlitz River (roughly 40 times the average annual preeruption suspended-sediment discharge of the Columbia River). Such prodigious sediment loading has wreaked considerable socioeconomic havoc, causing significant channel aggradation and loss of flood conveyance capacity. significant and ongoing engineering efforts have been required to mitigate these problems. The overall biological evolution of the eruption-impacted landscape can be viewed in terms of a framework of survivor legacies. Despite appearances to the contrary, a surprising number of species survived the eruption, even in the most heavily devastated areas. With time, survivor “hotspots” have coalesced into larger patches, and have served as stepping stones for immigrant colonization. The importance of biological legacies will diminish with time, but the intertwined trajectories of geophysical and biological successions will influence the geological and biological responses to the 1980 eruption for decades to come.
Landslides along the Winter Rim fault, Summer Lake, Oregon
Authors: Badger Thomas C. , Watters Robert J.
Published: April 2010

The field trip guide describes nine stops that examine the mechanisms and timing of some of the abundant and often gigantic landslides that occur along the Winter Ridge–Slide Mountain escarpment in south-central Oregon. Subsidence of Summer Lake basin, situated in the northwestern Basin and Range province, has exposed a kilometer-thick Neogene sequence of dense volcanic flow rocks overlying very weak tuffaceous sedimentary rocks in the bounding escarpment. Subsidence is accommodated on the 58-km-long Winter Rim fault system, a normal fault which is capable of producing Mw ≈ 7 earthquakes with near-field, maximum horizontal acceleration approaching 1 g on the bedrock footwall. Gigantic rock slides cubic kilometers in volume scallop the southwestern portion of the escarpment, and their deposits run out as rock avalanches several kilometers onto the basin floor. Limit-equilibrium slope stability analyses support observations that these gigantic bedrock landslides initiate within the weak tuffaceous sedimentary rocks along shallow, east-dipping, planar failure surfaces one to two kilometers in length; are insensitive to groundwater fluctuations; and, are stable under static conditions. Strong ground motions appear requisite to trigger landsliding and are necessary to replicate the long, shallow failure surfaces. Landslide, colluvial, and lacustrine deposits on the hanging wall have undergone widespread post-emplacement deformation, which may involve large-scale seismogenic lateral spreading and flow sliding controlled by the saturated, fine-grained basin fill.
The Boring Volcanic Field of the Portland-Vancouver area, Oregon and Washington
Authors: Evarts Russell C. , Conrey Richard M. , Fleck Robert J. , Hagstrum Jonathan T.
Published: April 2010

More than 80 small volcanoes are scattered throughout the Portland-Vancouver metropolitan area of northwestern Oregon and southwestern Washington. These volcanoes constitute the Boring Volcanic Field, which is centered in the Neogene Portland Basin and merges to the east with coeval volcanic centers of the High Cascade volcanic arc. Although the character of volcanic activity is typical of many monogenetic volcanic fields, its tectonic setting is not, being located in the forearc of the Cascadia subduction system well trenchward of the volcanic-arc axis. The history and petrology of this anomalous volcanic field have been elucidated by a comprehensive program of geologic mapping, geochemistry, 40Ar/39Ar geochronology, and paleomag-netic studies. Volcanism began at 2.6 Ma with eruption of low-K tholeiite and related lavas in the southern part of the Portland Basin. At 1.6 Ma, following a hiatus of ~0.8 m.y., similar lavas erupted a few kilometers to the north, after which volcanism became widely dispersed, compositionally variable, and more or less continuous, with an average recurrence interval of 15,000 yr. The youngest centers, 50-130 ka, are found in the northern part of the field. Boring centers are generally monogenetic and mafic but a few larger edifices, ranging from basalt to low-SiO2 andesite, were also constructed. Low-K to high-K calc-alkaline compositions similar to those of the nearby volcanic arc dominate the field, but many centers erupted magmas that exhibit little influence of fluids derived from the subducting slab. The timing and compositional characteristics of Boring volcanism suggest a genetic relationship with late Neogene intra-arc rifting.
Geoarchaeological themes in a dynamic coastal environment, Lincoln and Lane Counties, Oregon
Authors: Davis Loren G. , Jenevein Steven A. , Punke Michele L. , Noller Jay S. , Jones Julia A. , Willis Samuel C.
Published: April 2010

Regional-scale processes of tectonism, late Quaternary marine transgression, and patterns of aeolian deposition and erosion largely control the geoarchaeological character of the Oregon coast. Dramatic changes to the landscape of the Oregon coast since the Last Glacial Maximum drove the evolution of terrestrial and marine environmental processes which in turn conditioned the location and nature of prehistoric human activities. Due to the geologic complexities of Oregon's coast, archaeological investigations must address a broad range of geological factors that worked to greatly modify the ancient coastal landscape. In many ways, the modern Oregon coastline bears little resemblance to that associated with prehistoric coastal peoples prior to 3000 years ago, requiring geoscientific perspectives to reconstruct the late Quaternary environmental context. Through the integration of geologic concepts and information, geoarchaeology offers an effective means of finding early sites in the modern coastal landscape and in the now-submerged paleocoastal landscape.
A tectonic transect through the Salmon River suture zone along the Salmon River Canyon in the Riggins region of west-central Idaho
Authors: Blake David E. , Gray Keith D. , Giorgis Scott , Tikoff Basil
Published: April 2010

The Salmon River suture zone in west-central Idaho is a steep ocean-continent plate boundary separating Paleozoic-Mesozoic island-arc terranes and the ancestral western Laurentian margin that characterizes much of the central North American Cordillera. In the Riggins region, the most complete record of arc-continent collision and subsequent modification of the accretionary boundary is exposed because of the lower abundance of Cretaceous plutonism as compared to exposures of the boundary regionally along strike, and the deep degree of erosion along the Salmon River Canyon. Using recent mapping, microtectonic analysis, geochronological data, and structural models, this field trip explores the time-transgressive structures currently exposed across the Salmon River suture zone from the eastern foothills of the Seven Devils Mountains into the Salmon River Canyon.

The Salmon River suture zone contains a Late Jurassic to Early Cretaceous, west-vergent thrust belt that is overprinted along its eastern extent by the Late Cretaceous, transpressional western Idaho shear zone and Late Cretaceous(?) and Cenozoic ductile-brittle extensional structures. A distinct amalgamation of metavol-canogenic and metasedimentary rocks characterizes the thrust belt and includes the (1) northeastern Wallowa terrane, (2) western Salmon River belt, formally grouped with the Wallowa terrane, and (3) eastern Salmon River belt, known locally as the Riggins Group and Pollock Mountain Amphibolite. The western Idaho shear zone overprints the easternmost rocks and structures associated with the eastern Salmon River belt. It also contains heterogeneous units of tonalite, trondhjemite, and grano-diorite orthogneiss, as well as individual tonalite, granodiorite, and granite plutons that display a gradation and partitioning of deformation and strain internally within the shear zone. East of the magmatic injection zone located along the arc-continent boundary, Laurentian continental metasedimentary rocks and tonalite and granodio-rite plutons occupy the eastern portions of both the shear zone and larger suture zone. Geochronologic data, obtained largely from metaplutonic rocks in the McCall region south of the Riggins region, provide the temporal resolution to constrain current tectonic models proposed for Salmon River suture zone evolution.
Linking deep and shallow crustal processes in an exhumed continental arc, North Cascades, Washington
Authors: Miller Robert B. , Gordon Stacia M. , Bowring Samuel A. , Doran Brigid A. , McLean Noah M. , Michels Zachary D. , Shea Erin K. , Whitney Donna L. , Wintzer Niki E. , Mendoza Morgan K.
Published: April 2010

The magmatic arc represented by the crystalline core of the North Cascades (Cascades core) reached a crustal thickness of >55 km in the mid-Cretaceous. Eocene collapse of the arc was marked by migmatization, magmatism, and exhumation of deep-crustal (9-12 kb) rocks at the same time as subsidence and rapid deposition in nearby transtensional nonmarine basins. The largest region of deeply exhumed rocks, the migmatitic Skagit Gneiss Complex, consists primarily of leucocratic, biotite tonalite orthogneiss intruded between ca. 76-59 Ma and 50-45 Ma. Well-layered biotite gneiss is also widespread. U-Pb (isotope dilution-thermal ionization mass spectrometry) dating of zircon and monazite from trondhjemitic leucosome and biotite gneiss mesosome indicates that metamorphism and melt generation/crystallization occurred at least intermittently from ca. 71 to 47 Ma, and the youngest U-Pb dates overlap Ar/Ar (biotite, muscovite) dates, compatible with rapid cooling. Mesoscopic to map-scale, gently plunging, upright folds have hinge lines subparallel to orogen-parallel (NW-SE) lineations in the Skagit Gneiss Complex, and are as young as 48 Ma. Eocene top-to-northwest flow occurred in parts of the complex. The gently to moderately dipping foliation, subhorizontal lineation, and constrictional domains are compatible with ductile transtension linked to dextral-normal displacement on the Ross Lake fault system, the northeastern boundary of the Cascades core. On the south flank of the core, sediments were deposited in part at ca. 51 Ma in the Swauk basin and shortly afterward folded, and then intruded by 47 Ma Teanaway basaltic dikes. Extension taken up by these dikes ranges from ~10% to 43%. Extension directions from Teanaway and other Eocene dikes are arc-parallel to arc-oblique. The shallow-crustal extension direction is counterclockwise (mostly 10°-30°) to the ductile flow direction, implying decoupling of brittle and ductile crust; however, some coupling is supported by the temporal coincidence between basin formation and partial melting and ductile flow, and the upright folding of both the Skagit Gneiss Complex and Swauk basin. Arc-oblique to arc-parallel flow probably resulted in part from dextral shear along the plate margin, along-strike gradients in crustal thickness, and thermally controlled rheology.
Paleogene calderas of central and eastern Oregon
Authors: McClaughry Jason D. , Ferns Mark L. , Streck Martin J. , Patridge Karyn A. , Gordon Caroline L.
Published: April 2010

The John Day Formation of central and eastern Oregon, contains a widespread assemblage of both ash-flow and airfall tuffs, yet only a few corresponding caldera sources have been identified in the region. Investigators have long speculated on the sources of tuffs in the John Day Formation and have suggested that these pyroclastic rocks were vented from now buried eruptive centers in or marginal to a nascent Cascade Range. Recent detailed geologic mapping in the John Day and Clarno Formations, however, indicates the presence of at least three large-scale rhyolite caldera complexes centered along the northeast-trending axis of the Blue Mountains. This field guide describes a three-day geologic transect, from the scenic high desert of central Oregon eastward across the axis of the Blue Mountains, that will examine the physical volcanology and geologic setting of the 41.50-39.35 Ma Wildcat Mountain caldera exposed along the crest of the Ochoco Mountains, the 29.56 Ma Crooked River caldera at Prineville, and the 29.8 to 28.1 Ma Tower Mountain caldera near Ukiah.
Geological and geophysical perspectives on the magmatic and tectonic development, High Lava Plains and northwest Basin and Range
Authors: Meigs Andrew , Scarberry Kaleb , Grunder Anita , Carlson Richard , Ford Mark T. , Fouch Matt , Grove Tim , Hart William K. , Iademarco Mike , Jordan Brennan , Milliard Justin , Streck Martin J. , Trench David , Weldon Ray
Published: April 2010

A large part of the northwestern United States has undergone extensive late Cenozoic magmatic activity yielding one of the great continental volcanic provinces on Earth. Within this broader area lies the High Lava Plains province, the focus of this field guide. For our purposes, the High Lava Plains is a middle and late Cenozoic volcanic upland, contiguous with and gradational into the Basin and Range province to the south.

The High Lava Plains province of southeastern Oregon is characterized by thin, widespread Miocene-Pleistocene lava flows of primitive basalt and a belt of silicic eruptive centers. The rhyolitic rocks generally are successively younger to the northwest, describing a mirror image to the basalt plateau and rhyolite age progression of the Snake River Plain. The High Lava Plains is associated with a zone of numerous, small northwest-striking faults and lies at the northern limit of major Basin and Range normal faults. The abundant late Cenozoic bimodal volcanism occupies an enigmatic intracontinental tectonic setting affected by Cascadia subduction, Basin and Range extension, the Yellowstone plume, and lithospheric topography at the edge of the North American craton. The purpose of this field trip is to focus on the late Cenozoic lithospheric evolution of this region, through the lens of the High Lava Plains, by considering structural, geophysical, petrologic, and temporal perspectives.

A grand tour southeast from Bend to Valley Falls, north to Burns, and then east to Venator, Oregon, takes participants from the eastern edge of the Cascade volcanic arc, across several basins and ranges in eastern Oregon, and onto the volcanic plateau of the High Lava Plains. Day 1 provides an overview of Newberry Volcano and the western edge of Basin and Range, including the Ana River and Summer Lake fault zones. On Day 2, the early magmatic and extensional history of the region is explored along the Abert Rim range-front fault. Participants are introduced to the bimodal volcanism within the High Lava Plains, with focus on the Harney Basin and Rattlesnake ignimbrite event. An evening session will highlight geophysical results from the High Lava Plains, including new data from one of the largest active-source seismic experiments to be conducted in North America. Day 3 activities examine early bimodal volcanic history of the eastern High Lava Plains and the late Miocene and Pliocene subsidence history on the east edge of the Harney Basin east of Burns, Oregon.
Snowpack data collection in the Mount Hood area using SNOTEL and geomorphic events related to snowmelt
Authors: Strobel Michael L. , Lea Jon , Brunengo Matthew J. , Pedone Paul F.
Published: April 2010

This field trip guide describes a one-day loop from Portland eastward around Mount Hood and returning through the Columbia River Gorge. The purpose is to visit a SNOTEL (SNOwpack TELemetry) site to observe processes and instrumentation applied in automated snowpack data collection, as well as observe geomorphic features related to snowmelt in the western United States. Annual snow accumulation in the higher elevations in the western United States provides a critical source of water for irrigation, hydroelectric power generation, municipal water supplies, and recreation. Snowmelt, however, also can cause various hydrogeologic hazards, such as floods and debris flows.
Coastal geomorphology, hazards, and management issues along the Pacific Northwest coast of Oregon and Washington
Authors: Allan Jonathan C. , Witter Robert C. , Ruggiero Peter , Hawkes Andrea D.
Published: April 2010

Development along the coasts of Oregon and Washington is threatened by a variety of natural hazards, including coastal erosion, landslides, earthquakes, and tsunamis. Property losses have increased significantly in recent years due to past land-use and management practices and an intensification of the physical processes that drive coastal change. This field trip will visit a number of sites that document or illustrate the processes that shape Pacific Northwest coastal geomorphology and create hazards, including potentially catastrophic tsunamis generated by the Cascadia subduction zone. New research documenting ocean processes (including the role of changing wave climates, storm surges, El Nino's, and sea-level rise), tsunamis, and the effects of coastal subduction caused by great earthquakes will be covered. Also examined is the human response, which includes constructing coastal engineering structures, the establishment of coastal “erosion” hazard zones, and various mitigation efforts that are being implemented to prepare for future tsunamis. The field trip concludes on the southern Washington coast at Cape Disappointment State Park adjacent to the Columbia River, where construction of the Columbia River jetties, river flow regulation, and dredging and disposal activities have affected the sediment budget of the Columbia River littoral cell, resulting in changing sediment conditions and management practices for this cell.
Tuff cones, tuff rings, and maars of the Fort Rock–Christmas Valley basin, Oregon
Authors: Brand Brittany D. , Heiken Grant
Published: April 2010

Hydrovolcanic eruptions occur when rising magma violently fragments while mixing with shallow surface water or groundwater. These eruptions, among the most violent on Earth, generate hundreds to thousands of explosions throughout the course of an eruptive event. Each of these explosions ejects a mixture of juvenile and accidental clasts, gas, and water droplets. The solid materials either fall to the ground from tephra jets or collapse to form pyroclastic density currents (PDCs). The deposits of these eruptions build up rings of bedded tuff around the vent, recording both a wide variety of pyroclastic depositional mechanisms, and important changes in the eruptive style with time. This field trip will explore the deposits of basaltic, hydrovolcanic eruptions in the Fort Rock–Christmas Valley basin, the location of an intermittent, fluctuating, widespread Pleistocene lake (Fossil Lake). Basaltic volcanoes erupted in the center of the lake basin are characterized by Surtseyan eruptions (standing water), along the lake basin margins by maar eruptions (groundwater), and beyond the lake margin by scoria cones. The focus of the trip will be Fort Rock (Surtseyan) and the Table Rock Complex (large Surtseyan-tuff cone, large maar, and seven minor craters). This trip offers the opportunity to examine (1) settings under which explosive hydrovolcanic eruptions occur, (2) depositional characteristics that infer eruptive conditions, (3) a wide variety of pyroclastic deposits (i.e., fallout through air or a body of water, eruption-fed subaqueous sediment gravity current deposits, PDC deposits), and (4) mega-dunes (200 m wavelength dunes associated with large scale, dilute, PDCs from an energetic, mafic hydrovolcanic eruption).