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This study investigated the interaction of disciplinary and interdisciplinary learning in a team-taught, first-year, interdisciplinary sustainability course. We surveyed (pre/post) both STEM (science, technology, engineering, and mathematics) and non-STEM majors (N = 241), assessing attitudes and content knowledge. Responses were analyzed using factor analysis, classical test theory, and Rasch analysis. Multivariate analyses of variance were performed to look for pre/post differences and differences between groups. Confirmatory factor analysis verified that the content knowledge items adequately assessed disciplinary and interdisciplinary understanding separately. Tests indicated an adequate item difficulty range, but also a need for more items at the higher end. All groups improved significantly over the semester. Slightly higher gains for STEM students and a correlation between disciplinary, and interdisciplinary learning might indicate a possible benefit of "disciplinary grounding." The instrument vetted through this study expands the number of validated sustainability content knowledge items. Further, it allows users to probe content knowledge along both interdisciplinary and disciplinary dimensions.

This study explored the expectancies and motivations that prompt audiences to attend a university science lecture series. The series features talks by science experts from the host campus and around the USA. Each lecture typically attracts between 300 and 600 attendees, including middle and high school student groups, university students, and families and adults from the area. We conducted 47 semi-structured interviews with attendees in order to evaluate their expectancies and motivations. A template analysis of the interviews was grounded in social cognitive and self-determination theories. Results suggest that participants were mostly driven by intrinsic motivations and acquired strong sensory outcome expectancies, such as novelty and activity. Participants also held physical outcome expectancies, such as social expectancies, though to a lesser extent. Both intrinsic and extrinsic motivations to attend the lecture series were associated with expectancies held prior to the event. Of those expectancies, the novelty, entertainment, and social outcomes were dominant. Other noteworthy outcome expectancies include status and self-reactivity. Parents and teachers held outcome expectancies, not only for themselves, but also for their children and students who attended the talks with them.

To address the low priority given to university-level outreach, the authors created an outreach program that makes it easy for scientists to connect with the public, while at the same time providing effective transfer of scientific research results to the public and the K-12 community. The result is a program called the Hot Science--Cool Talks Outreach Lecture Series, a regular event at the University of Texas at Austin (UT Austin) overseen by the university's Environmental Science Institute (ESI). The program combines lectures by scientists with hands-on activities, webcasts, and workshops for teachers, students, and the public. This paper describes the concept for this lecture series, its operation, and its unique outcomes for K-12 outreach. (Contains 4 tables and 2 figures.)

Stalagmites being prepared for paleoclimate analysis should typically be slabbed along the central growth axis. This is an important first step because it allows for the highest resolution of sampling with minimal over- or under-sampling of the growth layers. Further, stable isotope ratios and trace element concentrations along the central growth axis most closely record climate variability. Choosing how to slab to best expose the central growth axis for geochemical sampling is challenging based on external morphology alone. High-resolution X-ray computed tomography (XRCT) can provide the ability to discern the internal growth morphology of stalagmites non-destructively, inexpensively, and rapidly. These data can inform selection of optimal slabbing plane(s) and can help identify locations for preliminary U-series dating. We develop a conceptual screening model to assess rapidly the internal morphologies of uncut stalagmites. The specifics of screening the internal morphologies through XRCT scans include investigating the internal porosity of the sample, the number and size of voids and hiatuses, and the presence and absence of growth layers and growth axes. We demonstrate that XRCT scans capture the migration of center of growth in uncut stalagmites of both simple and complex internal morphologies. XRCT scanning facilitates the investigation of stalagmites with complex internal growth banding, opening up avenues to work on such samples when stalagmites with simpler internal morphologies are not available. Further, screening stalagmites for paleoclimate reconstructions using XRCT improves the sustainability of speleothem science by helping researchers select which stalagmites should be returned to caves without destructive slabbing, thereby minimizing impact on caves. [ABSTRACT FROM AUTHOR]

The application of stable isotopes in speleothem records requires an understanding of the extent to which speleothem calcite isotopic compositions reflect the compositions of the cave waters from which they precipitate. To test for equilibrium precipitation, modern speleothem calcite was grown on glass plates, so that the carbon and oxygen isotope composition of the calcite and the water from which it precipitated could be directly compared. The plates were placed on the tops of three actively growing stalagmites that occupy a 1 [m.sup.2] area in Harrison's Cave, Barbados, West Indies. Only some of the plate [delta][sup.13]C values and none of the plate [delta][sup.18]O values correspond to equilibrium values, indicating significant kinetic isotope effects during speleothem calcite growth. We investigate herein mechanisms that may account for the kinetic isotope effects. On each plate, speleothem calcite was deposited with distinct [delta][sup.18]O and [delta][sup.13]C compositions that increase progressively away from the growth axis, with up to 6.6 [per thousand] [sup.13]C and 1.7 [per thousand] [sup.18]O enrichments. The positive [delta][sup.13]C versus [delta][sup.18]O trends are likely a result of [sup.18]O and [sup.13]C Rayleigh-distillation enrichment in the HC[O.sup.-.sub.3] reservoir owing to progressive C[O.sub.2] degassing and CaC[O.sub.3] precipitation. The magnitude of the [delta][sup.13]C versus [delta][sup.18]O slope is likely controlled by the extent to which C[O.sub.2] hydration-hydroxylation reactions buffer the oxygen isotope composition of the HC[O.sup.-.sub.3] reservoir during calcite precipitation. Complete oxygen isotopic buffering of the HC[O.sup.-.sub.3] reservoir by C[O.sub.2] hydration-hydroxylation reactions will produce a vertical [delta][sup.13]C versus [delta][sup.18]O slope in calcite sampled along a growth layer. As oxygen isotope buffering of the HC[O.sup.-.sub.3] reservoir decreases to no buffering, the [delta][sup.13]C versus [delta][sup.18]O slope in calcite sampled along a growth layer will decrease from vertical to 0.52 at the cave temperature. In this study, modern speleothem calcite sampled along the growth layer produced a [delta][sup.13]C versus [delta][sup.18]O slope of 3.9, indicating incomplete oxygen isotope buffering of the HC[O.sup.-.sub.3] reservoir during calcite precipitation. Both modern and Holocene speleothem calcite from Barbados, sampled temporally along the growth axis, shows similar positive [delta][sup.13]C versus [delta][sup.18]O slopes. These results, along with the spatial variations in glass plate calcite carbon and oxygen isotope compositions, suggest that the isotopic composition of the Holocene speleothems is in part controlled by non-equilibrium isotope effects. In addition, there is a correlation between stalactite length and oxygen and carbon isotope ratios of calcite precipitated on the corresponding stalagmite and glass plate, which may be due to [sup.13]C and [sup.18]O enrichment of the HC[O.sup.-.sub.3] reservoir during C[O.sub.2] degassing--calcite precipitation along the overhanging stalactite. We compiled 165 published speleothem stable isotope records with a global distribution and found that most of these records show a positive covariation between [delta][sup.13]C and [delta][sup.18]O values. Speleothem stable isotope records may be influenced by kinetic isotope effects such that temperature-controlled equilibrium fractionation models alone cannot directly explain the significance of the variations in these records. Advancing the interpretation of these records requires the calibration of cave environmental conditions with the non-equilibrium isotope effects that cause [delta][sup.13]C and [delta][sup.18]O covariations in speleothems. Keywords: kinetic isotope effects, speleothems, oxygen isotopes, carbon isotopes, non-equilibrium, Barbados.

Oxygen, carbon, and strontium isotope variations in vein-filling calcite and quartz cements and their host rocks are used to elucidate the origin, spatial and temporal evolution, and migration pathways of fluids in the detachment Nuncios fold complex, northeastern Mexico. The folded Mesozoic sedimentary sequence contains two regional paleohydrostratigraphic units separated by a unit of low permeability. Two main generations of cements are present in both paleohydrostratigraphic units. Distinct differences exist between [[delta].sup.18]O, [[delta].sup.13]C, [sup.87]Sr/[sup.86]Sr, and fluid-inclusion temperatures of early vein-filling cements in the lower and the upper units. These differences, together with a strong correspondence between early cement and host-rock [[delta].sup.18]O and [[delta].sup.13]C values, suggest that early diagenetic fluids were compartmentalized between the two units. Late vein-filling cements have isotopic compositions and fluid-inclusion temperatures that converge to similar values, indicating a change to open fluid flow between the lower and upper units. We hypothesize that the fluid history of the Nuncios fold complex evolved in two main stages: (1) burial diagenesis and early folding, during which fluids were confined within individual units, and (2) late-stage folding, during which increased deformation associated with fold tightening caused the expulsion of fluid from the lower unit into the upper unit. Keywords: fluid migration, evaporite, isotopes, detachment fold, Sierra Madre Oriental.

Radiogenic isotopes have wide application to chemical stratigraphy, geochronology, provenance studies, and studies of temporal changes in Earth surface processes. This paper briefly reviews the principles of radiogenic isotope geochemistry and the distribution of a number of elements of interest in the environment, and then uses this information to explore the range of applications to chemical stratigraphy and other fundamental subjects of sedimentary geology. Many of these applications center on the reconstruction of secular variations in paleoseawater isotope signals. These 'seawater isotope curves' can be used for stratigraphic correlation and to assess changes through Earth history in processes such as tectonic uplift, climate change, biogeochemical cycling, ocean circulation, crustal growth, and surface water evolution. Understanding the modern biogeochemical cycle of the element/isotope system of interest is essential for gaining the maximum information regarding the operation of ancient cycles. The main sources of uncertainty for reconstructing seawater isotope curves involve diagenetic alteration, sample impurities, and errors in age assignments. Rigorous sample selection criteria and pretreatment methods are keys to reconstructing the most accurate seawater isotope curves. Applications are discussed for the Rb-Sr, Sm-Nd, La-Ce, Lu-Hf, Re-Os, U-Th-Pb, K-Ar, and cosmogenic isotope systems. Keywords: Isotopes; Chemostratigraphy; Seawater; Strontium; Rare earth elements; Geochronology; Provenance

Strontium isotopes are a unique tool to study soil-erosion dynamics. Changes in Sr isotope ratios ([87.sup]Sr/[.sup.86]Sr) provide a record of late Quaternary landscape denudation of the Edwards Plateau of central Texas, United States. The use of Sr isotopes as a tracer for soil erosion is based on the observation that, in central Texas, the [sup.87]Sr/[sup.86]Sr ratio of soil correlates with soil thickness. Plants and animals express the [sup.87]Sr/[sup.86]Sr ratio of exchangeable Sr in the soil. Therefore, we use changes in Sr isotope ratios through a well-dated stratigraphic sequence of fossil plants and animals in Hall's Cave, Kerr County, Texas, as a proxy for temporal changes in soil thickness. By using this record we are able to characterize late Quaternary climate-driven soil-erosion dynamics on the Edwards Plateau. We find that continuous erosion removed at least 180 cm of soil at a constant minimum rate of 11 cm/k.y.; this continuous phase of erosion ended ca. 5 ka. The Sr isotope record of soil erosion is consistent with late Quaternary environmental change in central Texas that has been independently modeled by using local and regional climate records. However, the rate of this climate-driven soil-erosion event was an order of magnitude slower than recent soil erosion caused by human land use. These results link erosion to century- to millennial-scale climate change and are cautionary evidence that even greater landscape degradation may result from coincident climatic variability and anthropogenic influences. Keywords: soil erosion, strontium, isotopes, Edwards Plateau, Quaternary.

Author(s): Robert B. Jackson (corresponding author) [1]; Jay L. Banner [2]; Esteban G. Jobbágy [1]; William T. Pockman [1, 3]; Diana H. Wall [4] The invasion of woody vegetation into [...]

A detailed chronology for four stalagmites from three central Texas caves separated by as much as 130 km provides a 71 000-yr record of temporal changes in hydrology and climate. Mass spectrometric [sup.238]U-[sup.230]Th and [sup.235]U-[sup.23]Pa analyses have yielded 53 ages. The accuracy of the ages and the closed-system behavior of the speleothems are indicated by interlaboratory comparisons, concordance of [sup.230]Th and [sup.231]Pa ages, and the result that all ages are in correct stratigraphic order. Over the past 71 000 yr, the stalagmites have similar growth histories with alternating periods of relatively rapid and slow growth. The growth rates vary over more than two orders of magnitude, and there were three periods of rapid growth: 71-60 ka, 39-33 ka, and 24-12 ka. These growth-rate shifts correspond in part with global glacial-interglacial climatic shifts. Paleontological evidence indicates that around the Last Glacial Maximum (20 ka), climate in central Texas was cooler and wetter than at present. This wetter interval corresponds with the most recent period of increased growth rates in the speleothems, which is consistent with conditions necessary for speleothem growth. The temporal shift in wetness has been proposed to result from a southward deflection of the jet steam due to the presence of a continental ice sheet in central North America. This mechanism also may have governed the two earlier intervals of fast growth in the speleothems (and inferred wetter climate). Ice volumes were lower and temperatures in central North America were higher during these two earlier glacial intervals than during the Last Glacial Maximum, however. The potential effects of temporal variations in precession of Earth's orbit on regional effective moisture may provide an additional mechanism for increased effective moisture coincident with the observed intervals of increased speleothem growth. The stalagmites all exhibit a large drop in growth rate between 15 and 12 ka, and they show very slow growth up to the present, consistent with drier climate during the Holocene. These results illustrate that speleothem growth rates can reflect the regional response of a hydrologic system to regional and global climate variability. Keywords: caves, Edwards Plateau, geochronology, paleoclimate, speleothems, uranium-series method.

Research developments during 1996 in earthquake seismology, tectonics and structural geology, volcanology, sequence stratigraphy, and studies on core and mantle to elucidate the inner structure of earth are reported. The studies on the slow earthquakes which are considered to precede bigger earthquakes are detailed. The discovery of the post-collisional extension collapse of the Taiwan mountain is also discussed. The studies indicate differential rotation rates between the inner core and the mantle.

Strontium isotope analysis of precisely dated calcite growth layers in Holocene speleothems from Barbados, West Indies, reveals high-resolution temporal variations in ground-water composition and may provide a new approach to documenting the links between climate variability and fluctuations in the hydrologic cycle such as recharge rates and flow paths. The speleothems grew in a cave that developed in a fresh-water aquifer in uplifted Pleistocene reef limestones. Three periods of ground-water Sr isotope evolution are observed: 87Sr/86Sr values decreased from 6 to 4 ka, increased from 4 to 1 ka, and decreased again after 1 ka. The Sr isotope oscillations appear to record periodic variations in the relative Sr fluxes to ground water from exchangeable soil sites vs. carbonate mineral reactions, as reflected in 87Sr/86Sr values of modern Barbados ground waters. A hydrologic model that explains changes in ground-water flow routes in karst aquifers as a function of amount of rainfall recharge can account for the speleothem Sr isotope record. Independent Holocene climate records that indicate a major period of aridity at around 1.3-1.1 ka in the American tropics correspond with periodic variations in rainfall on Barbados that are predicted by this hydrologic model.

Uplifted Pleistocene coral-reef terraces on Barbados, West Indies, constitute an aquifer that is built on low-permeability Tertiary pelagic rocks that overlie the Barbados accretionary prism. The downdip segments of the aquifer are composed of younger reef limestones that contain more aragonite and have higher 87Sr/86Sr and Sr/Ca ratios than the updip parts of the aquifer. Ground waters and host limestones display similar stratigraphic trends in 87Sr/86Sr and Sr/Ca. The ground waters have lower 87Sr/86Sr values, however, indicating that they acquire a significant fraction of their dissolved Sr through interaction with components of Tertiary rocks, which compose the underlying aquitard and parts of overlying soils. Geochemical modeling results indicate that ground-water evolution is controlled by (1) variations in the age and composition of the aquifer and aquitard rocks and (2) the relative roles of calcite dissolution, calcite recrystallization, and the transformation of aragonite to calcite. Sr isotopes can provide unique information for tracing ground-water evolution, which requires consideration of the multiple components and processes that make up even relatively simple limestone aquifer systems.

Fossil brachiopod shells are commonly used as a faithful record of the chemical and isotopic composition of the ancient ocean water in which they grew, owing to their stable mineralogy and their presence in marine strata throughout Phanerozoic time. The utility of these fossils for preserving ocean-water compositions is evaluated through analyses of multiple specimens that grew in contemporaneous sea water at individual stratigraphic horizons in the Mississippian-age Burlington-Keokuk Formation of mid-continent North America. Significant variations in Sr, C, and O isotopic compositions are observed in contemporaneous, non-luminescent shells, indicating that apparently pristine brachiopod shell material has been altered by post-depositional processes of diagenesis. The least-altered compositions at each horizon are used to estimate secular variations of 87Sr/86Sr in Early Mississippian ocean water. The estimated rates of change of ocean-water 87Sr/86Sr are comparable in magnitude to the rapid Sr isotopic changes documented for Cenozoic ocean water, for which high-frequency glacial cycles are inferred as a driving mechanism. The rigorous assessment of diagenetic effects on the isotopic signatures of marine phases is requisite for the advancement of high-resolution reconstructions of paleo-ocean chemistry.