Description: May 2015 GSA Today INTRODUCTION Many of the major geoscience conferences are experiencing increased attendance, making it impossible to feature all oral presentations. Hence, the number and value of poster presentations are on the rise. For example, during the past 10 years, posters consistently comprised ~66% of the presentations at the American Geophysical Union (AGU) Fall Meeting, but overall poster numbers grew rapidly and now represent thousands of presentations each day (Fig. 1). Similarly, the European Geosciences Union (EGU) General Assembly is now made up of 66% poster presentations, also resulting in thousands of poster presentations each day. Posters at the Geological Society of America (GSA) Annual Meeting comprised an average of 37% of presentations during the last decade. Figure 1 Number of recent poster presentations for three major geoscience conferences: GSA Annual Meeting, AGU Fall Meeting, and EGU General Assembly. Data provided by GSA, AGU, and EGU. In light of the increasing number of posters at large geoscience conferences, authors must work hard to give conspicuous, effective, and memorable poster presentations. In all the chaos of the poster hall at large conferences—socializing, searching for beverages and bathrooms, and the hundreds to thousands of simultaneous presentations—you have a lot of competition for people’s attention. Here, we provide a “road map” of strategic steps for presenters who want their science to stand out among the rising sea of posters. We also point out some key open-access resources that will further improve posters when paired with these strategies.

Description: March/April 2015 GSA Today Featured Article SCIENCE ARTICLE p. 4 Matthew W. Hughes et al. Full Text | PDF (5.6MB) ABSTRACT Airborne light detection and ranging (LiDAR) data were acquired over the coastal city of Christchurch, New Zealand, prior to and throughout the 2010 to 2011 Canterbury Earthquake Sequence. Differencing of pre- and post-earthquake LiDAR data reveals land surface and waterway deformation due to seismic shaking and tectonic displacements above blind faults. Shaking caused floodplain subsidence in excess of 0.5 to 1 m along tidal stretches of the two main urban rivers, greatly enhancing the spatial extent and severity of inundation hazards posed by 100-year floods, storm surges, and sea-level rise. Additional shaking effects included river channel narrowing and shallowing, due primarily to liquefaction, and lateral spreading and sedimen-tation, which further increased flood hazard. Differential tectonic movement and associated narrowing of downstream river chan-nels decreased channel gradients and volumetric capacities and increased upstream flood hazards. Flood mitigation along the large regional Waimakariri River north of Christchurch may have, paradoxically, increased the long-term flood hazard in the city by halting long-term aggradation of the alluvial plain upon which Christchurch is situated. Our findings highlight the potential for moderate magnitude (MW 6–7) earthquakes to cause major topo-graphic changes that influence flood hazard in coastal settings.

Description: February 2015 GSA Today Featured Article GROUNDWORK p. 28 Nicole D. LaDue, Cheryl Brown Manning Full Text | PDF (83KB) How do we ensure the health of our geology departments with a steady stream of majors and build an informed public prepared to make important decisions on geoscience issues? The Next Generation Science Standards (NGSS) are a critical step, and they require the support of geoscientists nationwide. The NGSS demonstrate an expanded emphasis on earth-science topics (such as natural resource distribution, human impacts on climate, and geologic history) compared to previous standards (NGSS, 2012; National Research Council, 1996). The NGSS present a rare opportunity to significantly improve K–12 earth-science education nationally because they (1) include up-to-date, timely topics important for public decision making; and (2) increase the rigor and prominence of earth-science content in K–12 classrooms. However, adoption of the NGSS requires state-level legislative action. Without support from geoscientists at the state level, the implementation of NGSS nationwide is threatened.

Description: February 2015 GSA Today Featured Article SCIENCE ARTICLE p. 4 Xiaobo Tian, M. Santosh Full Text | PDF (1.3MB) ABSTRACT Global mantle convection significantly impacts the processes at Earth’s surface and has been used to gain insights on plate driving forces, lithospheric deformation, and the thermal and compositional structure of the mantle. Upper-mantle seismic anisotropy has been widely employed to study both present and past deformation processes at lithospheric and asthenospheric depths. The eastern China region was affected by extreme mantle perturbation and crust-mantle interaction during the Mesozoic, leading to large-scale destruction of the cratonic lithosphere, accompanied by widespread magmatism and metallogeny. Here we use teleseismic shear wave splitting measurements to evaluate the lithosphere and upper mantle deformation beneath this region. Our results from some of the individual and station averages show WNW-ESE- to NW-SE–trending fast polarization direction, similar to those observed in eastern Asia in some previous studies, consistent with the direction of Pacific plate subduction during the Cenozoic. This feature suggests that the asthenospheric flow beneath the eastern China region is influenced by the subduction of the western Pacific or Philippine plate. However, most of our data show E-W- or ENE-WSW–trending fast polarization direction, which is inconsistent with subduction from the east. The seismic stations in this study are located near the Qinling-Dabie-Sulu orogenic belt, which formed through the collision between the North and South China blocks during the Late Paleozoic–Triassic, and the anisotropy with an E-W- or ENE-WSW–trending fast polarization direction parallel to the southern edge of the North China block suggests lithospheric compressional deformation due to the collision between the North and South China blocks. Although the deep root of the craton was largely destroyed by cratonic reactivation in the late Mesozoic, our results suggest that the “fossilized” anisotropic signature is still preserved in the remnant lithosphere beneath eastern China.

Description: January 2015 GSA Today Featured Article 2014 GSA PRESIDENTIAL ADDRESS p. 4 Harry Y. McSween Jr. Full Text | PDF (912KB) ABSTRACT Planetary geoscience had very little presence in GSA’s first century, but it has a long history in GSA publications. Beginning with the Moon, the transformation of the planets and their satellites from astronomical objects into geological worlds has taken place largely by geologic mapping using telescope and spacecraft imagery and by the application of stratigraphic principles to these new data sets. Compositional data from orbital remote sensing, chronological information from crater densities, and the added dimension of petrology and geochemistry from surface rovers and laboratory analyses of samples, where available, have cemented geology’s central place in planetary exploration. The present focus on characterizing planetary paleoenvironments and the search for life further buttresses geology’s role in planetary exploration and serves as the next step in the expansion of our discipline beyond Earth.

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.