Daniel P. Murray

Fractional crystallization in granites of the Sierra Nevada: How important is it?

Although compositional variation in zoned calc-alkalic plutons is often ascribed to crystal fractionation, diagnostic large-scale field evidence of crystal accumulation in these slowly cooled bodies is generally missing. In many plutons, however, small-scale crystal cumulates have been preserved as layered schlieren and in microcosm may allow an assessment of the importance of crystal fractionation in their host pluton9s development. Small, widely separated patches of schlieren in the Tuolumne Intrusive Series, Yosemite National Park, California, formed as cumulates. Their darkest layers show high concentrations of magnetite, sphene, biotite, horn-blende, and zircon, and have unusually fractionated major and trace element compositions (FeO >33%; Al 2 O 3 in chondrites ∼750; Zr ∼2000 ppm). The layers define smooth trends on major and trace element Al 2 O 3 variation diagrams that diverge strongly from patterns for the main-sequence rocks of the Tuolumne Series and granitoids throughout the Sierra Nevada. Removal of such cumulates from any main-sequence magma would produce Al-rich evolved rocks, not the Al- poor felsic rocks of the pluton. The findings suggest that fractional crystallization did not produce the dominant chemical patterns seen in the Tuolumne and similar Sierra Nevada granites.

Increasing Learning in Introductory Geoscience Courses Using Lecture Tutorials

Students often leave introductory geoscience courses without learning the scientific perspective, and we developed Lecture Tutorials to help alleviate this problem. Lecture Tutorials are 10–20 minute interactive worksheets that students complete in small groups in class after a short introductory lecture. They are specifically designed to combat alternative conceptions and increase learning on difficult topics. Our study shows that Lecture Tutorials increase student learning in the classroom more than just lecture alone. On related multiple choice questions asked before and after the Lecture Tutorial (but after a short lecture on the topic), student scores increased 19%. When a subset of these questions was given before and after an extended lecture instead of a Lecture Tutorial, student scores did not increase by a statistically significant amount. On the multiple choice assessment questions given on exams relating to the information covered in the Lecture Tutorials, students who completed the Lecture Tutorials scored significantly higher than students who heard just lecture. In addition, students feel that they are an important and useful part of their learning experience. Lecture Tutorials are being disseminated and are available for instructor use.

Role for microorganisms in the formation of iridium anomalies

We propose a microbial role in the enhancement, erasure, dispersal, and creation of certain sedimentary iridium anomalies such as those of the Cretaceous/Tertiary boundary. The proposal is based on laboratory experiments that have demonstrated the ability of some bacteria and fungi to concentrate iridium from solution and to dissolve iridium from source igneous and meteoritic rocks.

Barriers to College Students Learning How Rocks Form

Students do not have a good understanding of how rocks form. Instead, they have many non-scientific alternative conceptions to explain different aspects of rock formation. Using 10 interviews and nearly 200 questionnaires filled out by students at four different colleges, we identified many alternative conceptions students have about rock formation. We then used themes within those alternative conceptions to identify the underlying conceptual barriers that cause them. Conceptual barriers are deeply-held conceptions that prevent students from understanding scientific explanations. One conceptual barrier can cause many alternative conceptions, and alternative conceptions can be the result of more than one conceptual barrier. The seven conceptual barriers identified in the study that prevent students from understanding rock formation are Deep Time, Changing Earth, Large Spatial Scale, Bedrock, Materials, Atomic Scale, and Pressure. Because of these conceptual barriers, students cannot form scientifically correct mental models of how rocks form, resulting in alternative conceptions, so the conceptual barriers need to be overcome before students truly learn the scientific explanations of how rocks form. The results of this study can be applied to other areas of geology in addition to rock formation.

Middle Devonian to Permian plutonism and volcanism in the N American Appalachians

Summary Mid-Devonian to late Palaeozoic igneous activity in the N American Appalachians occurs in the eastern portions of the orogen. Represented radiometric ages are almost continuous from 250 to 370 Ma and older, thus overlapping Acadian and Alleghanian orogenic events. In many instances igneous activity is generally similar to that initiated earlier in the Palaeozoic. Plutonic rocks consist of granitoids with subordinate intermediate to mafic rocks. Plutonism is mainly of ‘Caledonian’ or alkalic variety and is dissimilar to subduction-related magmatism of the Andean type. Regional synthesis indicates that some general distinctions of plutonism occur across strike as well as along strike from S to N within the orogen in eastern N America. In the southern Appalachians granites and minor contemporaneous gabbros occur in all lithotectonic zones between the Blue Ridge and the Coastal Plain. These plutons are commonly syn-kinematic in the eastern Piedmont where Alleghanian deformation and metamorphism are best exhibited, but are late- to post-kinematic to the W. The rocks include metaluminous biotite and megacrystic granites and lesser peraluminous two-mica granites. Late Palaeozoic igneous activity is sparse to absent in the central Appalachians. In New England several kinds of mid-Devonian to Carboniferous igneous activity are represented. Biotite and biotite + muscovite granitoids dominate the central terranes, whereas the more easterly Avalon zone is intruded by alkalic-peralkalic plutonic rocks and contains minor bimodal volcanics. Final Permian plutonism includes intrusion of homogeneous metaluminous to peraluminous granite. Within the Canadian Maritimes biotite and megacrystic granites followed by mildly alkalic varieties dominate the Devonian-Carboniferous plutons of New Brunswick and Newfoundland, whereas muscovite + biotite rocks are prominent in the Meguma terrane of Nova Scotia. Volcanism, which is bimodal, is best documented in New Brunswick and northern Nova Scotia. Igneous activity of Permian age is not recognized in the Canadian Maritimes. The petrological diversity together with the considerable span of time represented by the late Palaeozoic igneous activity in the N American Appalachians indicates repeated and locally prolonged anatexis of a variety of heterogeneous crustal sources. The alkalic and bimodal suites are characteristic of extensional or anorogenic tectonics. The more aluminous rocks are generally compositionally similar to the Caledonian and, to a lesser extent, the Hercynian suites of Europe. Overall the igneous activity may reflect relatively independent rifting and accretion of small crustal plates of diverse thicknesses and compositions in which magmatism was not related to a simple subduction island-arc setting.

Post-Acadian metamorphism in the Appalachians

Summary Well-documented post-Acadian metamorphism occurs at three locales along the eastern flank of the Appalachians, where it has affected Avalonian basement and/or Carboniferous cover. Carboniferous rocks of coastal New Brunswick display a greenschist-facies metamorphism of Pennsylvanian to Permian age which largely post-dates associated Alleghanian ductile deformation. In southeastern New England sedimentary rocks of late Pennsylvanian age have undergone an amphibolite-facies Barrovian metamorphic event (275–290Ma) that is syn- to post-ductile deformation and is truncated by peraluminous granite. Considerations of patterns of metamorphism in surrounding crystalline rocks implies that at least two distinct late Palaeozoic tectonothermal events have affected New England. In the Piedmont of Virginia and the Carolinas amphibolite-facies metamorphism (roughly 260–310 Ma) is synchronous with the emplacement of syn-kinematic granitoids. In all three areas isogradic patterns, where determinable, are complex, reflecting the effects of later faulting and fault-controlled retrograde metamorphism. In the USA at least, Alleghanian metamorphism also affected areas well beyond the boundaries of Avalonian terranes sensu stricto into the polydeformed crystalline terrane to the W (Inner Piedmont, Merrimack synclinorium). Within these crystalline rocks the Permian thermal overprint appears to be focussed along shear zones. Late Palaeozoic regional metamorphism in the Appalachians probably reflects crustal thickening related to continent-continent or continent-microcontinent collisions characterized by heat transfer along fundamental tectonic boundaries, and not simply proximity to late Palaeozoic igneous activity or subduction-zone tectonics.

Evaluation and Testing of Driver-Assistive Truck Platooning: Phase 2 Final Results

Phase 2 final results are described for the FHWA Exploratory Advanced Research project titled Heavy Truck Cooperative Adaptive Cruise Control: Evaluation, Testing, and Stakeholder Engagement for Near Term Deployment, which evaluates the commercial feasibility of driver-assistive truck platooning (DATP). The project was led by Auburn University, in partnership with Peloton Technology, Peterbilt Trucks, Meritor WABCO, and the American Transportation Research Institute. DATP is a form of cooperative adaptive cruise control for heavy trucks (two-truck platoons). It takes advantage of the increasing maturity of vehicle-to-vehicle (V2V) communications (and the expected widespread deployment of V2V connectivity based on dedicated short-range communications over the next decade) to improve freight efficiency, fleet efficiency, safety, and highway mobility as well as reduce emissions. Notably, truck fleets can implement DATP regardless of the regulatory timeline for dedicated short-range communications. The Phase 2 analysis built on Phase 1 and included a testing program of a DATP prototype (with detailed SAE Type 2 fuel economy testing), wireless communications optimization, traffic modeling to understand the impact on roadways at various levels of market penetration, and additional analysis of methods to find DATP partners as well as aerodynamic simulations to understand drag on the vehicles. Detailed analysis of the fuel economy testing data is provided.

Sleuthing Through the Rock Cycle: An Online Guided Inquiry Tool for Middle and High School Geoscience Education

ABSTRACT The rock cycle is a key component of geoscience education at all levels. In this paper, we report on a new guided inquiry curricular module, Sleuthing Through the Rock Cycle, which has a blended online/offline constructivist design with comprehensive teaching notes and has been successful in pilot use in Rhode Island middle and high school classrooms over the past 3 y. The module consists of two overarching activities: (1) SherRock Holmes and the Case of the Mystery Rock Samples, and (2) Cracking the Case of the Changing Rocks. The module encourages hands-on activities, peer collaboration, and real-time teacher review of embedded textual and reflection components. Overall, Rhode Island teachers report that the module is an outstanding teaching tool and that the associated professional development is empowering.

Harnessing the Power of Relational Databases for Managing Subsurface Geotechnical and Geologic Data

Knowledge of surface and subsurface geology as well as geotechnical properties is fundamental to the planning and development of transportation systems. Through dynamic linkage of readily available spatial geographic information system data and subsurface borehole data stored in a relational database, we have created a spatially referenced, digital catalog of borehole data for two pilot areas in Rhode Island. The borehole database is populated with data from Rhode Island Department of Transportation geotechnical reports and supplemental data from the U.S. Geological Survey groundwater site inventory system as well as local storm-water and sewer projects. Most of these data were previously stored in paper format, making historical or inter-project data comparisons very difficult, if not impossible. Consolidation of these data in a single relational database yields two primary benefits: Historical data are readily accessible for review and, therefore, can be easily incorporated into the planning stages of new projects, and sophisticated analysis of the region becomes possible with access to data from multiple projects with both spatial and temporal layers. Geologic data include bedrock geology, surface outcrops, unconsolidated materials, soil type, topographic and orthophotographic base maps, and location of boreholes and wells. Subsurface data include land-surface elevation, depth to water table, depth to bedrock, and presence or absence of fill, high and low blow-count zones, and organic sediment. The digital catalog is distributed on a CD-ROM that includes ArcView project files and an Access relational database. The borehole data are also accessible through the Internet (http://geo.uri. edu/borehole/index.asp), with public retrieval access for all users but data entry restricted to registered users only.

Distracted Driving Countermeasures for Commercial Vehicles

The purpose of this synthesis was to report the state of research and practice with the intent of examining both distractions, as well as any protective (safety enhancing) effects of particular devices. Distracted driving for commercial drivers was defined as attending to tasks not directly related to operating the vehicle. A literature review was conducted to assess recent research and current issues. The primary focus was to further understand driver distraction. It consisted of reports and analyses available from academic, government, and industry sources. Because available truck and bus technology capabilities have been changing dramatically over the last 10 to 15 years, literature cited here was published within that time frame. The information is included in the following sections: the nature of distracted driving, driver tasks unique to professional drivers, countermeasure technologies and their effectiveness, and operational strategies and recommended practice. As driver distraction was found to be an extremely complex issue with much of the historical research presenting conflicting results, considerably more research is suggested to fully understand the physical, cognitive, and emotional attributes of driver distraction. Based on the results of the literature review, a screening survey was developed to identify fleet managers willing to participate in structured interviews to understand their view of distracted driving and countermeasures they have put in place to reduce the risk of crashes related to distraction. The response size was small; there were 34 survey responses from motor carriers with 21 follow-up structured interviews conducted, with large and small fleets represented. There were 13 survey responses from large and small fleet motor coach representatives. Survey responses were primarily subjective responses to subjective questions and although not a representative sample of the larger population, still revealing because of the comparative information they provide. It was concluded that understanding how distraction types affect driving performance is important to improving the efficacy of countermeasures in triggering monitoring devices. Keywords: Driver distraction; Language: en