Description: December 2014 GSA Today Featured Article GROUNDWORK p. 4 How scientometry is killing science A.M. Celal Sengör Abstract | Full Text | PDF (4MB) ABSTRACT “ Publish or perish” is making science perish. When I was a student, one of my professors once said that the quality of a field geologist is assessed through gossip. When I asked him what he meant by it, he responded by pointing out that unlike in laboratory work or purely theoretical endeavors, a field geologist’s work was difficult to impossible to replicate and therefore to check. One therefore relied on the opinion of those people who were closely associated with that work through similar interest or actual collaboration or simply close acquaintanceship with the author, since publication in a reputable journal does not always guarantee high-quality work. When one needed evaluation of a certain geologist’s work, one asked those people’s opinion who were familiar with it.

Description: December 2014 GSA Today Featured Article SCIENCE ARTICLE p. 4 Brad S. Singer, Nathan L. Andersen, Hélène Le Mével, Kurt L. Feigl, Charles DeMets, Basil Tikoff, Clifford H. Thurber, Brian R. Jicha, Carlos Cardona, Loreto Córdova, Fernando Gil, Martyn J. Unsworth, Glyn Williams-Jones, Craig Miller, Judy Fierstein, Wes Hildreth, and Jorge Vazquez Abstract | Full Text | PDF (4MB) ABSTRACT Explosive eruptions of large-volume rhyolitic magma systems are common in the geologic record and pose a major potential threat to society. Unlike other natural hazards, such as earthquakes and tsunamis, a large rhyolitic volcano may provide warning signs long before a caldera-forming eruption occurs. Yet, these signs—and what they imply about magma-crust dynamics—are not well known. This is because we have learned how these systems form, grow, and erupt mainly from the study of ash flow tuffs deposited tens to hundreds of thousands of years ago or more, or from the geophysical imaging of the unerupted portions of the reservoirs beneath the associated calderas. The Laguna del Maule Volcanic Field, Chile, includes an unusually large and recent concentration of silicic eruptions. Since 2007, the crust there has been inflating at an astonishing rate of at least 25 cm/yr. This unique opportunity to investigate the dynamics of a large rhyolitic system while magma migration, reservoir growth, and crustal deformation are actively under way is stimulating a new international collaboration. Findings thus far lead to the hypothesis that the silicic vents have tapped an extensive layer of crystal-poor, rhyolitic melt that began to form atop a magmatic mush zone that was established by ca. 20 ka with a renewed phase of rhyolite eruptions during the Holocene. Modeling of surface deformation, magnetotelluric data, and gravity changes suggest that magma is currently intruding at a depth of ~5 km. The next phase of this investigation seeks to enlarge the sets of geophysical and geochemical data and to use these observations in numerical models of system dynamics.

Description: November 2014 GSA Today Featured Article SCIENCE ARTICLE p. 4 Preexisting fractures and the formation of an iconic American landscape: Tuolumne Meadows, Yosemite National Park, USA Richard A. Becker, Basil Tikoff, Paul R. Riley, Neal R. Iverson Abstract | Full Text | PDF (4MB) ABSTRACT Tuolumne Meadows, in Yosemite National Park (USA), is a large sub-alpine meadow in the Sierra Nevada Mountains. Immediately adjacent to Tuolumne Meadows—and underlain by the same bedrock lithology (Cathedral Peak Granodiorite)—are vertical rock faces that provide exceptional opportunities to climbers. While the presence of a broad meadow suggests bedrock erodibility, the vertical rock walls indicate bedrock durability. We propose that the Tuolumne Meadows’s landscape is the result of variable glacial erosion due to the presence or absence of pre-existing bedrock fractures. The meadows and valleys formed because of concentrated tabular fracture clusters—a distinctive and locally pervasive type of fracturing—that were particularly susceptible to glacial erosion. In contrast, the vertical rock walls consist of sparsely fractured bedrock that was originally bounded by zones of pervasive tabular fracture clusters. Glacial erosion preferentially removed the highly fractured rock, forming prominent ridges in the upland surrounding Tuolumne Meadows. The orientation and spacing of the tabular fracture clusters, relative to ice flow, has exerted a fundamental control on the geomorphology of the area. The erosional variability exhibited by a single lithology indicates that the degree of fracturing can be more important than the host lithology in controlling landscape evolution.

Description: November 2014 GSA Today Featured Article GROUNDWORK p. 4 Evolution of Paleontology: Long-term gender trends in an earth-science discipline Roy E. Plotnick, Alycia L. Stigall, Ioana Stefanescu Abstract | Full Text | PDF (4MB) ABSTRACT The historical development of gender diversity in paleontology may be representative of similar changes across the geosciences. An analysis of the programs of the ten North American Paleontological Conventions held since 1969 shows a steady increase in the participation by women in the discipline. Notably, the proportion of male authorship on abstracts was stable while female authorship contribution increased. Much of the growth in female authorship is due to increased collaboration and recognition of student participation with junior authorship. These changes are just starting to be reflected at more senior levels; strategies need to be implemented to ensure that young female geoscientists are retained and developed.

Description: October 2014 GSA Today Featured Articles SCIENCE ARTICLE p. 4 New insights into debris-flow hazards from an extraordinary event in the Colorado Front Range Jeffrey A. Coe, Jason W. Kean, Jonathan W. Godt, Rex L. Baum, Eric S. Jones, David J. Gochis, Gregory S. Anderson Full Text | PDF (1.8MB) ABSTRACT Rainfall on 9–13 September 2013 triggered at least 1,138 debris flows in a 3430 km 2 area of the Colorado Front Range. The historical record reveals that the occurrence of these flows over such a large area in the interior of North America is highly unusual. Rainfall that triggered the debris flows began after ~75 mm of antecedent rain had fallen, a relatively low amount compared to other parts of the United States. Most flows were triggered in response to two intense rainfall periods, one 12.5-hour-long period on 11–12 September, and one 8-hour-long period on 12 September. The maximum 10 min. intensities during these periods were 67 and 39 mm/hr. Ninety-five percent of flows initiated in canyons and on hogbacks at elevations lower than a widespread erosion surface of low slope and relief (〈2600 m). These flows were on steep (〉25°), predominantly south- and east-facing slopes with upslope contributing areas 〈3300 m 2 . Flows with the largest scars and longest travel distances occurred at elevations above 2600 m on steep slopes with contributing areas 〉3300 m 2 . Areal concentrations of debris flows revealed that colluvial soils formed on sedimentary rocks were more susceptible to flows than soils on crystalline rocks. This event should serve as an alert to government authorities, emergency responders, and residents in the Front Range and other interior continental areas with steep slopes. Widespread debris flows in these areas occur infrequently but may pose a greater risk than in areas with shorter return periods, because the public is typically unprepared for them.

Description: September 2014 GSA Today Featured Articles SCIENCE ARTICLE p. 4 A cosmogenic view of erosion, relief generation, and the age of faulting in southern Africa Paul R. Bierman, Ryan Coppersmith, Kathryn Hanson, Johann Neveling, Eric W. Portenga, Dylan H. Rood Full Text | PDF (5.2MB) ABSTRACT Southernmost Africa, with extensive upland geomorphic surfaces, deep canyons, and numerous faults, has long interested geoscientists. A paucity of dates and low rates of background seismicity make it challenging to quantify the pace of landscape change and determine the likelihood and timing of fault movement that could raise and lower parts of the landscape and create associated geohazards. To infer regional rates of denudation, we measured 10 Be in river sediment samples and found that south-central South Africa is eroding ~5 m m.y. −1 , a slow erosion rate consistent with those measured in other non-tectonically active areas, including much of southern Africa. To estimate the rate at which extensive, fossil, upland, silcrete-mantled pediment surfaces erode, we measured 10 Be and 26 Al in exposed quartzite samples. Undeformed upland surfaces are little changed since the Pliocene; some have minimum exposure ages exceeding 2.5 m.y. (median, 1.3 m.y.) and maximum erosion rates of 〈0.2 m m.y. −1 (median, 0.34 m m.y. −1 ), consistent with no Quaternary movement on faults that displace the underlying quartzite but not the silcrete cover. We directly dated a recent displacement event on the only recognized Quaternary-active fault in South Africa, a fault that displaces both silcrete and the underlying quartzite. The concentrations of 10 Be in exposed fault scarp samples are consistent with a 1.5 m displacement occurring ca. 25 ka. Samples from this offset upland surface have lower minimum limiting exposure ages and higher maximum erosion rates than those from undeformed pediment surfaces, consistent with Pleistocene earthquakes and deformation reducing overall landscape stability proximal to the fault zone. Rates of landscape change on the extensive, stable, silcretized, upland pediment surfaces are an order of magnitude lower than basin-average erosion rates. As isostatic response to regional denudation uplifts the entire landscape at several meters per million years, valleys deepen, isolating stable upland surfaces and creating the spectacular relief for which the region is known.

Description: August 2014 GSA Today ABSTRACT Hydraulic engineering is increasingly relied upon to provide the necessary dry-season discharge for Peru’s hydroelectricity generation. Redirecting stream flow can yield unintended consequences, however, and here we document the wholesale contamination of the Lake Junín National Reserve by acid mine drainage from the Cerro de Pasco mining district. Since construction of the Upamayo Dam in 1932, the Río (river) San Juan, which drains the Cerro de Pasco region, has been seasonally redirected into Lake Junín. As a result, the upper several decimeters of sediment in the lake contain peak concentrations of Cu, Zn, and Pb of ~6000 ppm, ~50,000 ppm, and ~2000 ppm, respectively, with the latter two greatly exceeding the United States Environmental Protection Agency (EPA) limits for the entire 150 km 2 lake basin. That the source of the contamination to Lake Junín is acid mine drainage from Cerro de Pasco is supported by spatial gradients in metal concentrations, authigenic calcite (marl) concentrations, and the isotopic record of Junín water. Today, the upper 50 cm of sediment in Lake Junín contain ~60,400, 897,600, and 40,900 metric tons of Cu, Zn, and Pb, respectively, which is equivalent to ~5.1 years’ worth of Zn extraction and ~0.7 years’ worth of Pb extraction from mining operations at Cerro de Pasco at current rates.

Description: August 2014 GSA Today INTRODUCTION Geoscientists are some of most prolific producers of three-dimensional (3-D) data. These data do not belong in our computers—they belong in our hands. The power of computers to make accurate and speedy calculations on 3-D data sets is impossible for humans to match. Likewise, the power of the human mind and its sensory system to perceive qualitative aspects of physical objects is currently beyond computers. Three-dimensional printing, shorthand for a host of technologies more broadly described as “rapid prototyping,” is transforming how scientists, engineers, doctors, and artists interact with and understand 3-D data and models by allowing those data to be touched and viewed from any angle under real-world conditions. Importantly, 3-D printing produces tangible objects that are obviously intuitive to students, non-geoscientists, and decision makers.

Description: July 2014 GSA Today ABSTRACT Learning in “the field” has long held a prominent role in the education of geoscientists. Despite the expense, time, and liability risks associated with fieldwork, field experiences are widely perceived as integral to both learning and professional preparation. Yet, to date, little research has addressed questions of what types of field experiences are valuable and what outcomes are desired. We report findings from survey data collected at the 2010 and 2011 Geological Society of America Annual Meetings that characterize why undergraduate field education is valued within the geoscience community. While 89.5% of respondents ( n = 172) indicated that fieldwork should be an integral and required part of undergraduate education, only 36.5% agreed that a course in bedrock mapping was necessary. Fieldwork is valued mainly for perceived cognitive gains, such as knowledge and understanding, and for enabling learners to interact with geological phenomena in their natural state. We found few statistically significant differences between self-identified groups, suggesting that students, instructors, and professional geologists hold largely similar opinions about the value of field education. This study helps to identify long-term goals and outcomes of undergraduate educational fieldwork experiences and points to actions needed to align fieldwork experiences with educational goals, workforce needs, and actual learning outcomes.

Description: June 2014 GSA Today I am sure that most of you have noticed that GSA has been shifting its communications more and more to the new GSA Connected Community in the last year or so. Those of you who serve on various GSA committees should already have noticed this transition, which was approved by Council and is being implemented by GSA staff. GSA values your membership and appreciates every member's commitment and investment of resources in the Society, and we feel that the Connected Community will ultimately lead to more efficient and effective communication between the Society and our members as well as member-to-member discussions and exchanges. more ...