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Description: September 2015 GSA Today PREFACE: 1973 Geology Article Covers Baltimore Gneiss Geology ABSTRACT In the central Appalachian Piedmont the “basement complex” is an assemblage of 1,100- to 1,300-m.y.-old gneisses, migmatites, and amphibolites that crops out in “domes” mantled by younger metasedimentary rocks of the Glenarm Series. Aeromagnetic data and reconnaissance fieldwork indicate that a previously unknown Baltimore Gneiss dome, here called the Mill Creek dome, is present in southeastern Pennsylvania and northwestern Delaware. The discovery of previously unknown domes of Baltimore Gneiss has bearing on the thickness, structure, and regional relations of the Glenarm Series.

Description: September 2015 GSA Today First a Discovery, Then Digging Like Mad Scalpel. Knife. Shovel. A bulldozer’s blade. Cutting-edge science happens at a variety of scales, from the individual and intimate to the large-scale and collaborative. The publication of a special issue of Quaternary Research in Nov. 2014 dedicated to the scientific findings of the “Snowmastodon Project” highlights what can be done when natural history museums, governmental agencies, and academic institutions work toward a common goal. On 14 Oct. 2010, a third-generation bulldozer driver named Jesse Steele was pushing dirt as part of a reservoir expansion project high in the Rocky Mountains at Ziegler Reservoir, just outside Snowmass Village, Colorado, USA. The reservoir was to be enlarged to meet the needs of a growing population and a local ski resort, and up until that point, the work was right on schedule. When Steele pushed up some strange bones along with the usual lake muds, however, it was apparent that everything was about to change.

Description: August 2015 GSA Today ABSTRACT Today, relative sea-level rise (3.4 mm/yr) is faster in the Chesapeake Bay region than any other location on the Atlantic coast of North America, and twice the global average eustatic rate (1.7 mm/yr). Dated interglacial deposits suggest that relative sea levels in the Chesapeake Bay region deviate from global trends over a range of timescales. Glacio-isostatic adjustment of the land surface from loading and unloading of continental ice is likely responsible for these deviations, but our understanding of the scale and timeframe over which isostatic response operates in this region remains incomplete because dated sea-level proxies are mostly limited to the Holocene and to deposits 80 ka or older. To better understand glacio-isostatic control over past and present relative sea level, we applied a suite of dating methods to the stratigraphy of the Blackwater National Wildlife Refuge, one of the most rapidly subsiding and lowest-elevation surfaces bordering Chesapeake Bay. Data indicate that the region was submerged at least for portions of marine isotope stage (MIS) 3 (ca. 60–30 ka), although multiple proxies suggest that global sea level was 40–80 m lower than present. Today MIS 3 deposits are above sea level because they were raised by the Last Glacial Maximum forebulge, but decay of that same forebulge is causing ongoing subsidence. These results suggest that glacio-isostasy controlled relative sea level in the mid-Atlantic region for tens of thousands of years following retreat of the Laurentide Ice Sheet and continues to influence relative sea level in the region. Thus, isostatically driven subsidence of the Chesapeake Bay region will continue for millennia, exacerbating the effects of global sea-level rise and impacting the region’s large population centers and valuable coastal natural resources.

Description: August 2015 GSA Today STEM education focused on the perspectives and needs of Native American students is a missing element in the current U.S. educational system (Barnhardt, 1997). Consequently, very few Native American students pursue careers in the STEM disciplines, especially earth science (Beede et al., 2011). Ironically, many Native American students eventually learn that earth science is a tool their ancestors used for thousands of years and that a general mastery of science and engineering skills can benefit and help maintain their communities. Most Native students, however, see no connection between Western science and the goal of preserving their cultural identities. If STEM faculty, teachers, and other scientists can better explain the links between traditional indigenous knowledge, Western science, and community needs, we contend that this approach would attract more Native American and other underrepresented students to earth science.

Description: July 2015 GSA Today INTRODUCTION The past few years have seen the rapid development and availability of unmanned aerial vehicles (UAV). Popularly called “drones,” they are remotely operated vehicles that can be fixed-wing aircraft or helicopters. UAVs are being developed for use in everything from product delivery (e.g., Albright, 2014) to farming (e.g., Papadopoulos et al., 2014). Especially popular are micro UAV helicopters, which are usually in the form of small aerial platforms that have four or more propellers (Fig. 1). This configuration provides great maneuverability, stability, and control. Newer UAVs have built-in GPS systems that provide even greater control and make it easy for an inexperienced person to quickly learn the basics of flying. Their size also makes them easy to transport to even the most remote areas (Fig. 1). They require very little launch and recovery space, and the cost of a basic unit is such that even the total loss of a vehicle is not financially catastrophic (Carrivick et al., 2013). Their low cost also means that multiple UAVs can be used, providing for redundancy if one is lost or damaged.

Description: July 2015 GSA Today ABSTRACT The formation of metamorphic core complexes is not well understood, which is why these large geological structures are still interesting subjects. They seem to have been formed by erosion of upper crustal rocks and exhumation of mid-crustal rocks. However, it is not clear how the lower crust and underlying mantle have responded. Many core complexes in the western United States are underlain by a flat Moho discontinuity, and some others possess a crustal root. Here, we present evidence of the Chapedony metamorphic core complex in the Central Iranian plateau. We show that the overall lithosphere and continental crust were thinned beneath regions of surface extension. The core complex is located within a continental rift and was exhumed at a rate of ~0.75–1.3 km/m.y. during the main phase of oceanic subduction of the Arabian plate beneath the Central Iranian block between ca. 49 and 30 Ma. The thinning of the underlying lithosphere appears to have been compensated by hot asthenosphere, as indicated by low seismic velocities in the Central Iranian block. We conclude that the development of the core complex involved lithospheric removal associated with extension and upwelling of hot asthenosphere, although we are aware of the fact that the structure could have been substantially modified by subsequent processes like slab break-off and associated uplift of the Central Iranian plateau.

Description: June 2015 GSA Today ABSTRACT The Yilgarn Craton of Western Australia hosts a regional acid saline groundwater system and hundreds of ephemeral saline lakes characterized by complex acid brines. These acid saline lakes and groundwaters have pH as low as 1.4 and salinities as high as 32% total dissolved solids. The low pH formed by a combination of processes dependent upon the host rock lithology and mineralogy, climate, weathering, organisms, and time. Although these modern acid saline environments are relatively rare, they have both ancient terrestrial and extraterrestrial counterparts. Understanding acidification processes provides enhanced understanding of hydrosphere-lithosphere-atmosphere-biosphere interactions. These environments present evidence of new brine evolution pathways and suggest the potential for future intense acid brine environments.

Description: June 2015 GSA Today INTRODUCTION We live on a planet with an active surface that is modified and deformed at multiple temporal and spatial scales owing to diverse processes occurring at plate boundaries and plate interiors. The processes of mid-ocean-ridge spreading, mountain building, subduction of tectonic plates, mantle drag, intra-continental deformation, earthquakes, and volcanism cross traditional disciplinary boundaries (Fig. 1A). Understanding these lithospheric processes is valuable not only for intellectual curiosity and to refine our working knowledge of plate tectonics, but also for understanding threats to life, property, and infrastructure. Computer modeling and simulation are increasingly powerful tools that researchers employ to better understand lithospheric deformation and unravel the complex feedbacks that drive the evolution of Earth’s surface. The field is poised for a significant advance to take advantage of recent expansions in computing power, improved representation of idealized processes, increased data availability, and better communication between software developers and geoscientists.

Description: May 2015 GSA Today ABSTRACT A smart city is one that harmonizes with the geology of its territory and uses technology to develop sustainably. Until the Republican Times, Rome was a smart city. The ancient settlement of Rome benefitted from abundant natural resources. City expansion took place in such a way as to not substantially alter the morphological and geological features of the area; natural resources were managed so as to minimize the risks. The geology, together with prudent management, ensured Rome’s fortune. Naples, which developed in a similar geological context and at almost the same time, was exposed to more geological hazards and had access to fewer natural resources. This was fatal for the city that, while remaining one of the most important of the Mediterranean, did not become the capital of an empire as Rome did. The histories of Rome and Naples highlight the important role of geology in the development of a city and the making of its fortune. Over time, fast urban expansion, rapid population growth, and the overuse of resources led to increased hazards for both cities. As a result, the cities became unstable and fragile, and several natural processes resulted in disasters.