American Geosciences Institute

ABSTRACT Rocks and geologic structures exposed at the surface in the Big Bend region of far west Texas, USA, preserve evidence of three significant North American plate-tectonic events: The late Paleozoic Marathon-Ouachita orogeny, the late Cretaceous–Paleogene Laramide orogeny, and the Neogene–present extensional event of Rio Grande rifting. Rocks here also preserve a 30-million-year span of magmatism that temporally straddles both the end of the early Cenozoic contraction event and the beginning of the more recent extension, and, therefore, record that transition. Modern terrestrial waters also contribute to the geology of this arid region, both with the Rio Grande’s incision exposing some of these rocks and with their hosting of groundwater and springs. Visits to sites during this four-day field trip in and around Big Bend Ranch State Park and Big Bend National Park will increase understanding of these geologic events. DEDICATION This field trip is dedicated to the memory of Blaine Hall, an exceptional friend and colleague to many of this field guide’s authors and an enthusiast of Big Bend geology. Blaine completed his B.S. in geology at University of Texas (UT)–El Paso, received his M.Sc. in geological oceanography from Dalhousie University, and carried out research in marine geology and geophysics while at Lamont-Doherty Earth Observatory of Columbia University. His industry experience began with Superior Oil in minerals exploration for Proterozoic placer gold and kimberlites in the Rockies, Canada, Kansas, and Arkansas. He then shifted to petroleum, beginning with studies of heavy oil reservoirs in California for Mobil Oil and continuing with exploration and production projects in Argentina and southern South America. Blaine returned to his native West Texas and spent the next ten years teaching geology and mathematics at Sul Ross State University. While there he was also active with the Chihuahuan Desert Research Institute, where he developed a permanent exhibit on the geology of the Davis Mountains and presented educational workshops. He joined Texas Parks and Wildlife in 2010 as an interpretive ranger at Big Bend Ranch State Park, and he helped direct research of master’s students from Sul Ross State University and collaborated with faculty from UT-Austin on early Paleozoic sedimentation and tectonics in the Solitario dome (see Fig. 0.1). Contents Introduction Tectonic Maps of the Big Bend Region Showing Cordilleran and Rio Grande Rift Structures Road Log Day 1: Big Bend Ranch State Park Day 2: West Side of Big Bend National Park Day 3: East Side of Big Bend National Park Day 4: Marathon to San Antonio Acknowledgments References Cited

Opening of the Arctic Ocean has been the subject of much debate, and the placement of terranes in the Early Mesozoic remains a crucial part of this important discussion. Several continental terranes complicate the palaeogeographical reconstruction. One such terrane is Crockerland, which has been inferred to explain sediment distribution in the Arctic throughout the Mesozoic. However, Triassic successions throughout the Arctic basins bear many similarities, and a common sedimentary source could offer a simpler explanation with fewer complications for the past configuration of the Arctic. The study's goal is to test the hypothesis of long-distance sediment transport from a common source in present-day Russia to all Arctic basins in the Triassic, and to demonstrate how estimates of sediment routing distances can improve pre-break-up plate-tectonic reconstructions. Results confirm that (1) the Arctic basins were closely connected prior to break-up in the Mesozoic, (2) based on regional facies distribution, sediment budgets, sediment modelling and detrital zircon age spectra, the Crockerland terrane is unlikely to have existed as a major sediment supplying area, (3) the reconstructed Arctic sediment routing system can help to constrain plate-tectonic models, and (4) statistical estimation of sediment transport is a novel and potentially important tool for improving plate-tectonic and palaeogeographical reconstructions. Supplementary material : A database for provenance study, detrital zircon age spectra and the sedimentary length calculations method are available at https://doi.org/10.6084/m9.figshare.c.6086468

Abstract Geoscientists have important roles in the management of the world's water at local, regional, national, and global scales. Geophysical information is critical to ensure that people have enough water for domestic, agricultural, industrial, and other needs. Given the current challenges of water management, it has never been more critical to promote awareness of water's place in earth system science. To encourage everyone to understand, conserve, and protect water, Earth Science Week 2021 will be held 10–16 October.

No one should be excluded from the geosciences. The more people who are included in exploration geophysics and related fields, the richer the profession becomes. That is just one of the reasons Earth Science Week 2019, 13–19 October, is focusing on the theme “Geoscience is for everyone.”

New Faces in G-I webinars and invited presentations at universities and conferences on topics related to offshore wind turbine foundations and/or excavation-induced ground movements.Her accomplishments and professional activities, only