Physical Sciences and Mathematics Commons^™

Unblocking Temperatures Of Viscous Remanent Magnetism In Displaced Granitic Boulders, Icicle Creek Glacial Moraines (Washington, Usa), Juliet G. Crider, Danika M. Globokar, Russ F. Burmester, Bernard A. Housen

Geology Faculty Publications

Viscous remanent magnetization (VRM) may partially overprint original magnetization in rocks displaced by geomorphic events. An established theoretical relationship between the time and temperature of acquisition of VRM and the time and temperature of demagnetization suggests that laboratory demagnetization (unblocking) of VRM can be used to estimate the displacement age of rocks. We test this hypothesis at four nested glacial moraines in the Icicle Creek drainage of central Washington, the ages of which were previously determined by cosmogenic surface exposure dating. The moraines are composed primarily of granodiorite boulders, and magnetic remanence is carried dominantly by magnetite. Both the maximum …

Effects Of Changes In Moisture Source And The Upstream Rainout On Stable Isotopes In Precipitation – A Case Study In Nanjing, Eastern China, Y. Tang, H. Pang, W. Zhang, Y. Li, Shuang-Ye Wu, S. Hou

Geology Faculty Publications

In the Asian monsoon region, variations in the stable isotopic composition of speleothems have often been attributed to the "amount effect". However, an increasing number of studies suggest that the "amount effect" in local precipitation is insignificant or even non-existent. To explore this issue further, we examined the variability of daily stable isotopic composition (δ18O) in precipitation from September 2011 to November 2014 in Nanjing, eastern China. We found that intra-seasonal variations of δ18O during summer were not significantly correlated with local rainfall amount but could be linked to changes in the moisture source location and rainout processes in the …

Expedition 350 Methods, Y. Tamura, C. J. Busby, P. Blum, G. Guèrin, G. D.M. Andrews, A. K. Barker, J. L. R. Berger, E. M. Bongiolo, M. Bordiga, Susan M. Debari, J. B. Gill, C. Hamelin, J. Jia, E. H. John, A. -S. Jonas, M. Jutzeler, M. A.C. Kars, Z. A. Kita, K. Konrad, S. H. Mahoney, M. Martini, T. Miyazaki, R. J. Musgrave, D. B. Nascimento, A. R.L. Nichols, J. M. Ribeiro, T. Sato, J. C. Schindlbeck, A. K. Schmitt, S. M. Straub, M. J. Vautravers, Y. Yang

Geology Faculty Publications

This chapter of the International Ocean Discovery Program (IODP) Expedition 350 Proceedings volume documents the procedures and tools employed in the various shipboard laboratories of the R/V JOIDES Resolution during Expedition 350. This information applies only to shipboard work described in the Expedition Reports section of this volume. Methods for shore-based analyses of Expedition 350 samples and data will be described in the individual scientific contributions to be published in the open literature or in the Expedition Research Results section of this volume.

This section describes procedures and equipment used for drilling, coring, and hole completion; core handling; computation of …

Expedition 350 Summary, Y. Tamura, C. J. Busby, P. Blum, G. Guèrin, G. D.M. Andrews, A. K. Barker, J. L.R. Berger, E. M. Bongiolo, M. Bordiga, Susan M. Debari, J. B. Gill, C. Hamelin, J. Jia, E. H. John, A.-S. Jonas, J. Jutzeler, M A.C. Kars, Z. A. Kita, K. Konrad, S. H. Mahony, M. Martini, T. Myiazaki, R. J. Musgrave, D. B. Nascimento, A. R.L. Nichols, J. M. Ribeiro, T. Sato, J. C. Schindlbeck, A. K. Schmitt, S. M. Straub, M. J. Vautravers, Y. Yang

Geology Faculty Publications

International Ocean Discovery Program (IODP) Hole U1436A (proposed Site IBM-4GT) lies in the western part of the Izu fore-arc basin, ~60 km east of the arc-front volcano Aogashima, ~170 km west of the axis of the Izu-Bonin Trench, and 1.5 km west of Ocean Drilling Program (ODP) Site 792, at 1776 meters below sea level (mbsl). It was drilled as a 150 m deep geotechnical test hole for potential future deep drilling (5500 meters below seafloor [mbsf]) at proposed Site IBM-4 using the D/V Chikyu. Core from Site U1436 yielded a rich record of Late Pleistocene explosive volcanism, including …

Multi-Episodic Remagnetization Related To Deformation In The Pyrenean Internal Sierras, Esther Izquierdo-Llavall, Antonio Casas Sainz, Belén Oliva-Urcia, Russ F. Burmester, Emilio L. Pueyo, Bernard A. Housen

Geology Faculty Publications

The Internal Sierras (IS) in the southern margin of the Western and Central Axial Zone (Southern Pyrenees) are affected by a syn-orogenic remagnetization that provides information to reconstruct deformation geometries at the time of acquisition of magnetization. Furthermore, the IS structure changes strike along its structural trend, from ∼N120 to 130°E in the western and eastern margins to ∼N070–090°E in the central part. Palaeomagnetic techniques have been used to (i) accurately define the timing of remagnetization with regard to deformation and (ii) determine if the along-strike trend variation in the IS was induced by deformation and thrust emplacement during the …

Katian Gssp And Carbonates Of The Simpson And Arbuckle Groups In Oklahoma, Jesse R. Carlucci, Daniel Goldman, Carlton E. Brett, Stephen R. Westrop, Stephen A. Leslie

Geology Faculty Publications

This guidebook was written for the 2015 International Symposium on the Ordovician System (ISOS) as a synopsis of the recent work (e.g., Goldman et al. 2007; Carlucci et al. 2014, forthcoming work for the ISOS meeting) on Ordovician-Silurian rocks of south-central and south-eastern Oklahoma. This new research and past studies (e.g., Harris 1957; Longman 1976; Longman 1982a, b; Fay et al. 1982a; Fay et al. 1982b) underscore the scientific importance of this region. The global stratotype section and point for the Katian Stage of the Upper Ordovician Series is examined on this trip. The first appearances of important graptolites, conodonts …

Geologic Map Of The Welcome Quadrangle And An Adjacent Part Of The Wells Quadrangle, Elko County, Nevada, Allen J. Mcgrew, Arthur W. Snoke

Geology Faculty Publications

Located in central Elko County, the Welcome and adjacent part of the Wells quadrangles expose a remarkable array of critical relationships for understanding the geologic history of the State of Nevada and the interior of the southwestern U.S. Cordillera. Covering the northern end of the East Humboldt Range and adjacent Clover Valley and Clover Hill, this map includes the northern terminus of the Ruby Mountains-East Humboldt Range metamorphic core complex. The oldest rocks in the State of Nevada (the gneiss complex of Angel Lake), and Nevada’s only exposures of Archean rock, form the core of a multikilometer scale, southward-closing recumbent …

Long-Term Explosive Degassing, Debris Flows And Volatile Release At West Mata Submarine Volcano, R. P. Dziak, D. R. Bohnenstiehl, E. T. Baker, H. Matsumoto, Jacqueline Caplan-Auerbach, R. W. Embley, S. L. Walker, T. -K. Lau, W. W. Chadwick Jr.

Geology Faculty Publications

West Mata is a 1200 m deep submarine volcano where explosive boninite eruptions were observed in 2009. The acoustic signatures from the volcano’s summit eruptive vents Hades and Prometheus were recorded with an in situ (~25m range) hydrophone during ROV dives in May 2009 and with local (~5km range) moored hydrophones between December 2009 and August 2011. The sensors recorded low frequency (1–40 Hz), short duration explosions consistent with magma bubble bursts from Hades,and broadband, 1–5 min duration signals associated with episodes of fragmentation degassing from Prometheus. Long-term eruptive degassing signals, recorded through May 2010, preceded a several …

Holocene Earthquakes And Right-Lateral Slip On The Left-Lateral Darrington-Devils Mountain Fault Zone, Northern Puget Sound, Washington, Stephen F. Personius, Richard W. Briggs, Alan R. Nelson, Elizabeth R. Schermer, J. Zebulon Maharrey, Brian L. Sherrod, Sarah A. Spaulding, Lee-Ann Bradley

Geology Faculty Publications

Sources of seismic hazard in the Puget Sound region of northwestern Washington include deep earthquakes associated with the Cascadia subduction zone, and shallow earthquakes associated with some of the numerous crustal (upper-plate) faults that crisscross the region. Our paleoseismic investigations on one of the more prominent crustal faults, the Darrington–Devils Mountain fault zone, included trenching of fault scarps developed on latest Pleistocene glacial sediments and analysis of cores from an adjacent wetland near Lake Creek, 14 km southeast of Mount Vernon, Washington. Trench excavations revealed evidence of a single earthquake, radiocarbon dated to ca. 2 ka, but extensive burrowing and …

Reconstruction Of The Hirnantian (Late Ordovician) Palaeotopography In The Upper Yangtze Region, Linna Zhang, Junxuan Fan, Qing Chen, Shuang-Ye Wu

Geology Faculty Publications

Reconstruction of the Hirnantian (Late Ordovician) palaeotopography in South China is important for understanding the distribution pattern of the Hirnantian marine depositional environment. In this study, we reconstructed the Hirnantian palaeotopography in the Upper Yangtze region based on the rankings of the palaeo-water depths, which were inferred according to the lithofacies and biofacies characteristics of the sections. Data from 374 Hirnantian sections were collected and standardized through the online Geobiodiversity Database. The Ordinary Kriging interpolation method in the ArcGIS software was applied to create the continuous surface of the palaeo-water depths, i.e. the Hirnantian palaeotopography. Meanwhile, the line transect analysis …

Hydroacoustic Investigations Of Submarine Landslides At West Mata Volcano, Lau Basin, Jacqueline Caplan-Auerbach, R. P. Dziak, D. R. Bohnenstiehl, W. W. Chadwick, T. -K. Lau

Geology Faculty Publications

Submarine landslides are an important process in volcano growth yet are rarely observed and poorly understood. We show that landslides occur frequently in association with the eruption of West Mata volcano in the NE Lau Basin. These events are identifiable in hydroacoustic data recorded between ~5 and 20 km from the volcano and may be recognized in spectrograms by the weak and strong powers at specific frequencies generated by multipathing of sound waves. The summation of direct and surface-reflected arrivals causes interference patterns in the spectrum that change with time as the landslide propagates. Observed frequencies are consistent with propagation …

Multiple Migmatite Events And Cooling From Granulite Facies Metamorphism Within The Famatina Arc Margin Of Northwest Argentina, Sean R. Mulcahy, Sarah M. Roeske, William C. Mcclelland, Joshua R. Ellis, Fred Jourdan, Paul R. Renne, Jeffrey D. Vervoort, Graciela I. Vujovich

Geology Faculty Publications

The Famatina margin records an orogenic cycle of convergence, metamorphism, magmatism, and extension related to the accretion of the allochthonous Precordillera terrane. New structural, petrologic, and geochronologic data from the Loma de Las Chacras region demonstrate two distinct episodes of lower crustal migmatization. The first event preserves a counterclockwise pressure-temperature path in kyanite-K-feldspar pelitic migmatites that resulted in lower crustal migmatization via muscovite dehydration melting at ∼12 kbar and 868°C at 461 ±1.7 Ma. The shape of the pressure temperature path and timing of metamorphism are similar to those of regional midcrustal granulites and suggest pervasive Ordovician migmatization throughout the …

Izu-Bonin-Mariana Rear Arc: The Missing Half Of The Subduction Factory, Yoshihiko Tamura, Abigail K. Barker, Cathy J. Busby, Julien L.R. Berger, Peter Blum, Everton M. Bongiolo, Gilles Guèrin, Manuela Bordiga, Graham D.M. Andrews, Susan M. Debari, James B. Gill, Cedric Hamelin, Jihui Jia, Eleanor H. John, Ann-Sophie Jonas, Martin Jutzeler, Myriam A.C. Kars, Zachary A. Kita, Kevin Konrad, Susan H. Mahony, Michelangelo Martini, Takashi Miyazaki, Robert J. Musgrave, Debora B. Nascimento, Alexander R.L. Nichols, Julia M. Ribeiro, Tomoki Sato, Julie C. Schindlbeck, Axel K. Schmitt, Susanne M. Straub, Maryline J. Vautravers, Yang Yang

Geology Faculty Publications

4GT) lies in the western part of the Izu fore-arc basin, ~60 km east of the arc-front volcano Aogashima, ~170 km west of the axis of the Izu-Bonin Trench, 1.5 km west of Ocean Drilling Program (ODP) Site 792, and at 1776 meters below sea level (mbsl). It was drilled as a 150 m deep geotechnical test hole for potential future deep drilling (5500 meters below seafloor [mbsf]) at proposed Site IBM-4 using the D/V Chikyu. Core from Site U1436 yielded a rich record of Late Pleistocene explosive volcanism, including distinctive black glassy mafic ash layers that may record large-volume …

Crustal Shortening, Exhumation, And Strain Localization In A Collisonal Orogen: The Bajo Pequeno Shear Zone, Sierra De Pie De Palo, Argentina, Joshua M. Garber, Sarah M. Roeske, Jessica Warren, Sean R. Mulcahy, William C. Mcclelland, Lauren J. Austin, Paul R. Renne, Graciela I. Vujovich

Geology Faculty Publications

The Bajo Pequeño Shear Zone (BPSZ) is a lower-crustal shear zone that records shortening and exhumation associated with the establishment of a new plate boundary, and its placement in a regional structural context suggests that local- to regional-scale strain localization occurred with progressive deformation. A kilometer-scale field and analytical cross section through the ~80 m thick BPSZ and its adjacent rocks indicates an early Devonian (405–400 Ma) phase of deformation on the western margin of Gondwanan continental crust. The earliest stages of the BPSZ, recorded by metamorphic and microstructural data, involved thrusting of a hotter orthogneiss over a relatively cool …

Melt Inclusion Evidence For Magma Evolution At Mutnovsky Volcano, Kamchatka, K. Robertson, A. Simon, T. Pettke, Sean R. Mulcahy, E. Smith, O. Selyangin, A. Kiryukhin, J. D. Walker

Geology Faculty Publications

Mutnovsky Volcano, located in Kamchatka, Russia, is a young volcano that has formed a series of four overlapping stratocones over its approximately 80 ka history. Erupted products at Mutnovsky range in composition from basalts to dacites; basalts are the most common. In this study, melt inclusions from representative samples of all erupted compositions from all four eruptive centers were analyzed to investigate the causes of the compositional heterogeneity, melt evolution, and pre-eruptive magma dynamics. Melt inclusions from Mutnovsky were sampled in olivine, plagioclase, orthopyroxene, and clinopyroxene. The melt inclusion data represent a wide range of melt compositions, from basalt through …

Post-Caledonian Brittle Fault Zones On The Hyperextended Sw Barents Sea Margin: New Insights Into Onshore And Offshore Margin Architecture, Kjetil Indrevær, Steffen G. Bergh, Jean-Baptiste Koehl, John-Are Hansen, Elizabeth R. Schermer, Arild Ingebrigtsen

Geology Faculty Publications

Onshore-offshore correlation of brittle faults and tectonic lineaments has been undertaken along the SW Barents Sea margin off northern Norway. The study has focused on onshore mapping of fault zones, the mapping of offshore fault complexes and associated basins from seismic interpretation, and the linkage of fault complexes onshore and offshore by integrating a high-resolution DEM, covering both onshore and offshore portions of the study area, and processed magnetic anomaly data. This study shows that both onshore and offshore brittle faults manifest themselves mainly as alternating NNE–SSW- and ENE–WSW-trending, steeply to moderately dipping, normal fault zones constituting at least two …

Unlocking The Secrets Of Al-Tobermorite In Roman Seawater Concrete, Marie D. Jackson, Sejung R. Chae, Sean R. Mulcahy, Cagla Meral, Rae Taylor, Penghui Li, Abdul-Hamid Emwas, Juhyuk Moon, Seyoon Yoon, Gabriele Vola, Hans-Rudolf Wenk, Paulo J.M. Monteiro

Geology Faculty Publications

Ancient Roman syntheses of Al-tobermorite in a 2000-year-old concrete block submerged in the Bay of Pozzuoli (Baianus Sinus), near Naples, have unique aluminum-rich and silica-poor compositions relative to hydrothermal geological occurrences. In relict lime clasts, the crystals have calcium contents that are similar to ideal tobermorite, 33 to 35 wt%, but the low-silica contents, 39 to 40 wt%, reflect Al³⁺ substitution for Si⁴⁺ in Q² (1Al), Q³ (1Al), and Q3 (2 Al) tetrahedral chain and branching sites. The Al-tobermorite has a double silicate chain structure with long chain lengths in the b [020] crystallographic direction, and …

Cascadia Fore Arc Seismic Survey: Open-Access Data Available, W. Steven Holbrook, Graham Kent, Katie Keranan, H. Paul Johnson, Anne Trehu, Harold Tobin, Jacqueline Caplan-Auerbach, Jeff Beeson

Geology Faculty Publications

The Cascadia subduction zone (CSZ), where the Juan de Fuca and Gorda plates subduct obliquely beneath North America at a rate of about 35 millimeters per year, poses major geological hazards to population centers of the northwestern United States. Despite the importance of the subducting slab in these hazards, the plate boundary is poorly mapped and understood, especially offshore.

Map Of The Late Quaternary Active Kern Canyon And Breckenridge Faults, Southern Sierra Nevada, California, C. C. Brossy, K. I. Kelson, Colin B. Amos, J. N. Baldwin, B. Kozlowicz, D. Simpson, M. G. Ticci, A. T. Lutz, O. Kozaci, A. Streig, R. Turner, R. Rose

Geology Faculty Publications

Surface traces of the Quaternary active Kern Canyon and Breckenridge faults were mapped via aerial reconnaissance, analysis of light detection and ranging (LiDAR) elevation data, review and interpretation of aerial photography, field reconnaissance, and detailed field mapping. This effort specifically targeted evidence of late Quaternary surface deformation and, combined with separate paleoseismic investigations, identified and characterized the North Kern Canyon, South Kern Canyon, and Lake Isabella sections of the Kern Canyon fault and the Breckenridge fault. The mapping presented here provides definitive evidence for previously unrecognized Holocene and late Pleistocene east-down displacement along the Kern Canyon and Breckenridge faults. Our …

Late Holocene Rupture History Of The Alpine Fault In South Westland, New Zealand, Kelvin Berryman, Alan Cooper, Richard Norris, Pilar Villamor, Rupert Sutherland, Trevor Wright, Elizabeth R. Schermer, Robert Langridge, Glenn Biasi

Geology Faculty Publications

Abstract Strata and fault relationships revealed in five trenches excavated across the recent trace of the Alpine fault at the Haast, Okuru, and Turnbull Rivers, South Westland, New Zealand, record the three most recent surface-faulting events. Using back-stripping techniques to remove the three faulting events and the sedimentary units associated with the faulting restores the cross-sections to gravel-bed floodplains at the Haast and Okuru Rivers, at about A.D. 750. Horizontal and vertical offsets of stream channels and terrace risers reveal characteristic displacements of about 8–9 m dextral and up to 1 m vertical per event. Cumulative dextral displacement is 25 …

Projecting Changes In Extreme Precipitation In The Midwestern United States Using North American Regional Climate Change Assessment Program (Narccap) Regional Climate Models, Shuang-Ye Wu

Geology Faculty Publications

Based on the physics of global circulation, many expect an enhanced greenhouse effect to lead to a more active hydrological cycle with more precipitation on average (Hennessy et al. 1997). This expected increase has been found in observations (Zhang et al. 2007) and has also been suggested by climate models, although these models are not consistent with respect to the spatial and temporal variability about this change. An increase in mean precipitation depth, assuming no change in the shape of the frequency distribution, would imply an increased frequency of heavy-precipitation events. However, some studies (Hennessy et al. 1997, Allen and …

Effectiveness Of Four Water-Bearing Zones Of The Glacierized Basin In Meltwater Runoff Modeling, Umesh K. Haritashya

Geology Faculty Publications

Meltwater runoff modeling from glacierized basins needs several input data, including total meltwater contributing area. This study utilizes optical remote sensing data to assess glacierized basins in the central Himalayas where snow and glaciers contribute substantially to the water resources. Result shows that there are four main water-bearing zones in the basin: (a) dry snow, (b) wet snow, (c) exposed glacial ice, and (d) debris-covered glacial ice, and it is possible to differentiate and map these zones and their spatio-temporal variations from satellite sensor data. These zones can then be incorporated in meltwater runoff modeling as separate entities because they …

Geology Of National Parks Modules For The Spreadsheets Across The Curriculum Library, H. L. Vacher, Thomas C. Juster, Judy Mcllrath, Mark Rains

Geology Faculty Publications

No abstract provided.

First Year Morphological Evolution Of An Artificial Berm At Fort Myers Beach, Florida, Katherine Brutsche, Ping Wang

Geology Faculty Publications

This Coastal and Hydraulics Engineering Technical Note (CHETN) documents the sediment characteristics and first year morphological evolution of an artificial berm placed just offshore in Fort Myers Beach, Florida, based on a series of field data collection periods during the first year after the berm construction.

Rock Magnetism Of Hematitic "Bombs" From The Araguainha Impact Structure, Brazil, Luigi Jovane, Elder Yokoyama, Takele Seda, Russ F. Burmester, Ricardo I.F. Trindade, Bernard A. Housen

Geology Faculty Publications

Hematite impact “bombs” are one of the most striking (and enigmatic) features of the large Araguainha impact structure in central Brazil. They have both porous or massive textures, elongated shapes from 5 to 50 cm in diameter, and botryoidal textures that suggest hydrothermal origin. Some authors have considered these objects as a possible analog of hematite nodules found in Mars, and consequently related to a hydrothermal system. Here we report rock magnetic measurements, X-ray diffraction and Mössbauer spectra for both massive and porous samples for a detailed description of the hematite. Room temperature magnetic measurements, including hysteresis loops, back-field and …

The 2007 Nazko, British Columbia, Earthquake Sequence: Injection Of Magma Deep In The Crust Beneath The Anahim Volcanic Belt, J. F. Cassidy, N. Balfour, C. Hickson, H. Kao, R. White, Jacqueline Caplan-Auerbach, S. Mazzotti, G. C. Rogers, I. Al-Khoubbi, A. L. Bird, L. Esteban, M. Kelman, J. Hutchinson, D. Mccormack

Geology Faculty Publications

On 9 October 2007, an unusual sequence of earthquakes began in central British Columbia about 20 km west of the Nazko cone, the most recent (circa 7200 yr) volcanic center in the Anahim volcanic belt. Within 25 hr, eight earthquakes of magnitude 2.3–2.9 occurred in a region where no earthquakes had previously been recorded. During the next three weeks, more than 800 microearthquakes were located (and many more detected), most at a depth of 25–31 km and within a radius of about 5 km. After about two months, almost all activity ceased. The clear P- and S-wave arrivals …

Structural Evolution Of A Composite Middle To Lower Crustal Section: The Sierra De Pie De Palo, Northwest Argentina, Sean R. Mulcahy, S. M. Roeske, W. C. Mcclelland, F. Jourdan, A. Iriondo, P. R. Renne, J. D. Vervoort, G. I. Vujovich

Geology Faculty Publications

The Sierra de Pie de Palo of northwest Argentina preserves middle to lower crustal metamorphic rocks that were penetratively deformed during Ordovician accretion of the Precordillera terrane to the Gondwana margin. New structural, petrologic, and geochronologic data from a 40 km structural transect reveals that the Sierra de Pie de Palo preserves a middle to lower crustal ductile thrust complex consisting of individual structural units and not an intact ophiolite and cover sequence. Top-to-the-west thrusting occurred intermittently on discrete ductile shear zones from ∼515 to ∼417 Ma and generally propagated toward the foreland with progressive deformation. Ordovician crustal shortening and …

Encyclopedia Of Snow, Ice And Glaciers, Vijay P. Singh, Pratap Singh, Umesh K. Haritashya

Geology Faculty Publications

The objective of this encyclopedia is to present the current state of scientific understanding of various aspects of earth’s cryosphere – snow, glaciers, ice caps, ice sheets, ice shelves, sea ice, river and lake ice, and permafrost – and their related interdisciplinary connections under one umbrella. Therefore, every effort has been made to provide a comprehensive coverage of cryosphere by including a broad array of topics, such as the atmospheric processes responsible for snow formation; snowfall observations; snow cover and snow surveys; transformation of snow to ice and changes in their properties; classification of ice and glaciers and their worldwide …

Timing, Distribution, Amount, And Style Of Cenozoic Extension In The Northern Great Basin, Christopher D. Henry, Allen J. Mcgrew, Joseph P. Colgan, Arthur W. Snoke, Matthew E. Brueseke

Geology Faculty Publications

This field trip examines contrasting lines of evidence bearing on the timing and structural style of Cenozoic (and perhaps late Mesozoic) extensional deformation in northeastern Nevada. Studies of metamorphic core complexes in this region report extension beginning in the early Cenozoic or even Late Cretaceous, peaking in the Eocene and Oligocene, and being largely over before the onset of “modern” Basin and Range extension in the middle Miocene. In contrast, studies based on low- temperature thermochronology and geologic mapping of Eocene and Miocene volcanic and sedimentary deposits report only minor, localized extension in the Eocene, no extension at all in …

Communications And 'Forestructures' At The Geological Intersection Of Caves And Subsurface Water Flow: Hermeneutics And Parochialism, Lee J. Florea, H. L. Vacher

Geology Faculty Publications

The direction of cave and karst science throughout its history has been partly determined by communication—or, more commonly, the lack of communication—between non-scientist cavers and non-caving physical geologists writing about karst. Within each community, advancement of ‘cave awareness’ occurred through a hermeneutic circle in which ‘forestructures’ guided progress. One result was regionalism of speleo-genetic theories developed within karst science because of the weight of evidence placed upon local or regional observations. Many speleogenetic theories of the mid-1900s suffer from this parochialism, failing to take into account findings from karst of different geologic settings. During the past half-century, the accumulated worldwide …