Spring Mountains Research Articles

Origin and emplacement of the Blue Diamond landslide breccia, southern Nevada, U.S.A.

ABSTRACT Landslide deposits are common in basin fill of tectonically active areas, including the Basin and Range province of western North America. However, interpreting and reconstructing ancient landsliding events from these deposits is challenging, but can be aided by detailed field analysis. Remnants of the Blue Diamond landslide breccia are exposed capping hills and ridges in the foothills of the eastern Spring Mountains near Blue Diamond, Nevada, USA. Uncertainties surrounding the origin and emplacement of the ancestral Blue Diamond landslide have emerged based on the disparate distribution of landslide outcrops. Therefore, in this study we used detailed sedimentological data and observations to interpret a two-phase emplacement history for the Blue Diamond landslide. Sedimentological observations are consistent with Blue Diamond landslide breccia emplacement as a rock avalanche. The presence of clastic dikes and flame structures and negligible incorporation of bedrock substrate material suggest that runout occurred over a saturated substrate. Flow transformation into a debris avalanche is ruled out because clast-count data show that debris entrainment was not sufficient to act as the sole mechanism behind the excessive mobility experienced by the Blue Diamond landslide. Instead, we propose that the excessive mobility was driven by flow entrainment of large Aztec Sandstone boulders and interaction with a saturated runout path substrate that caused a reduced basal frictional resistance, enabling initial emplacement onto Blue Diamond Hill. We therefore suggest that the Blue Diamond landslide was derived from a source area about 8.5 km northwest of the Blue Diamond townsite and flowed into the Blue Diamond Hill site where it was emplaced onto Moenkopi Formation atop the hill during the Miocene. Due to loading by this new overburden, incompetent gypsum horizons failed in the upper Kaibab Formation stratigraphically below the Moenkopi Formation. These failed gypsum horizons then served as a compound landslide rupture surface, transporting the overlying Moenkopi Formation and landslide breccia. This secondary emplacement likely ceased by late Miocene to Pliocene time.

Climate and landscape variation shapes the water balance of piñon pine-juniper woodlands

• Piñon pine-juniper woodlands are strongly influenced by water balance (WB) variation. • Southern Nevada woodlands are a model for future hot and dry conditions regionally. • WB magnitude was driven by climate; partitioning was shaped by landscape factors. • Tree transpiration partitioning and magnitude declined at moderate woodland densities. • Climate conditions and stand characteristics impart meaningful WB variation. Piñon pine-juniper woodlands are strongly influenced by water balance variation imparted by variation in climate, landscape attributes, and tree stand characteristics. To elucidate how these multiple factors shape woodland ecohydrology, we simulated the water balance of woodlands in the Spring (higher precipitation (PPT), higher potential evapotranspiration (PET)) and Sheep (lower PPT, lower PET) mountains of southern Nevada, USA. Simulations included: (1) elevation and climate (2000, 2200 and 2400 m; 3 scenarios); (2) low and moderate adult tree density (2 scenarios); and (3) south-facing, neutral, and north-facing aspects (3 scenarios; 18 scenarios in each mountain range). Due to the interplay between PPT and PET, the lower PPT Sheep mountains were atmospherically less dry (PPT – PET) than the Spring mountains. Following this, the Sheep mountains had higher transpiration partitioning into evapotranspiration (T/ET), whereas transpiration magnitude was higher in the Spring mountains. In both mountain ranges, soil moisture and tree transpiration were highest in winter and spring, and low in summer. T/ET was maximized at 12–15 m 2 ha − 1 basal area, illustrating the increasing influence of interception at higher tree densities. Thus, the water balance of these woodlands was driven by PPT, yet partitioning was shaped by PET and tree stand density. Interplay between soil moisture, tree transpiration, evaporation and interception is a defining characteristic of woodlands in southern Nevada, and may be influenced at broader and finer spatial scales. Better understanding of climatic, landscape, and tree stand factors may help to explain high water balance variation observed in woodlands across the western US, and improve understanding of how future change to piñon pine-juniper ecosystems may be realized.

Practical Applications of The Outlook for Endowment and Pension Funds

For decades, a 60/40 equity/bond allocation has been the favored allocation method for endowment and pension fund managers. In <ext-link><italic><bold>The Outlook for Endowment and Pension Funds</bold></italic></ext-link>, from the Summer 2021 issue of <italic><bold>The Journal of Wealth Management</bold></italic>, <bold>Haim Mozes</bold>, a professor of accounting at <bold>Fordham University’s Gabelli School of Business,</bold> and <bold>John Steffens</bold>, a founder and managing member of <bold>Spring Mountain Capital</bold>, formulate an outlook for the future performance of the 60/40 allocation. Mozes and Steffens identify the economic conditions that drove the 60/40 allocation’s past success and then forecast future economic scenarios. Most significant to the future performance of endowment and pension funds is the possible scenario of continued low bond yields coupled with low economic growth. In that scenario, low bond yields would produce weak returns on bonds while weak economic growth would produce poor returns on equities; the overall performance of the 60/40 allocation would be weak. The authors assess the strategies that funds are considering in order to meet their target objectives in the event of such a scenario, including increasing allocations to public equities and other risky assets.

An Inventory of Springsnails (Pyrgulopsis spp.) in and Adjacent to the Spring Mountains, Nevada

Springsnails (genus Pyrgulopsis, hereafter pyrgs) are small freshwater aquatic gastropods that occur in isolated springs in western North America. Pyrgs are species of conservation concern, but patterns of occupancy and speciation are complex. We investigated patterns of occurrence for pyrgs in the Spring Mountains, Clark County, Nevada. We were primarily concerned with identifying springs containing the species P. deaconi, the Spring Mountains pyrg, and P. turbatrix, the southeast Nevada pyrg. We identified species through genetic analysis of the COI-1 mitochondrial region and examined patterns of genetic structure. We located aquatic gastropods in 26 springs and analyzed 420 aquatic gastropods, of which 392 were pyrgs, the remainder representing an unknown species of Physa. Of the 26 springs, 25 contained pyrgs and 5 contained Physa sp. For pyrgs, at COI-1 we identified a total of 29 haplotypes that formed 6 distinct monophyletic groups. Five of the 6 groups were consistent with pyrgs previously identified: P. bacchus, P. deaconi, P. fausta, P. turbatrix, and an unknown species which had been identified previously in the Grapevine Springs. The sixth group, found in 2 springs, does not match any reference specimen and is genetically divergent from the other 5 groups. It is most closely related to P. micrococcus. Prior to this study, P. bacchus had not been located in the Spring Mountains. Both P. deaconi and P. turbatrix were located in multiple springs on both the east and west sides of the Spring Mountains, even though the Las Vegas Valley (east) and Pahrump Valley (west) are hydrologically distinct. At the scale of the hydrologic basin, genetic structure was not discernable; haplotype divergence did not align with basin boundaries and the most common haplotype for P. turbatrix occurred on both the east and west sides of the Spring Mountains. While there was little evidence for genetic structuring at the hydrologic-basin level, there was good evidence for structuring at the level of the individual spring. All told, 79% (23/29) of pyrg haplotypes were unique to specific springs, suggesting that pyrg diversity primarily occurs at the level of the individual spring.

Regeneration dynamics of Great Basin bristlecone pine in southern Nevada

Great Basin bristlecone pine (Pinus longaeva D.K. Bailey) is an important and long-lived tree species found at high elevations in the interior southwest of the United States, but little is known about its regeneration requirements and response to disturbance. We conducted extensive surveys of seedling regeneration and environmental attributes of regeneration sites in undisturbed forest dominated by this species in the Spring Mountains of southern Nevada. Additional surveys tallied new seedling densities and site attributes 4 years after a wildfire in the same area. Seedlings, saplings, and juvenile trees were less abundant than adult trees in the unburned forest, and soils had lower bulk density and greater depth, moisture, and soil organic matter under adult trees than in open areas. Seedling distributions in both unburned and burned forest showed a negative relationship to a heat load index governed by aspect. The density of new seedlings after the fire was negatively related to distance from unburned forest edges. Seedlings were found in clusters and were associated with adult trees (live or dead) in both unburned and burned stands. Seedling emergence from animal-dispersed caches was more frequent in burned habitats than in unburned habitats. These natural regeneration dynamics provide potential guidance for restoration efforts in this ecosystem.

Physiological and Molecular-genetic Characteristic of Bacteria Strains, Isolated from Mountain Spring and Mineral Waters in Plovdiv Region, Bulgaria

The present study aims to investigate the microbiological research of mineral and spring mountain waters in the region of Plovdiv, Bulgaria. In Bulgaria, there are mineral and mountain spring waters, which are not subjected to physicochemical and microbiological control by the Regional Health Inspectorate, yet they are the most widely used springs by the population as sources of drinking water. The methodology is including the determination of total number of mesophilic aerobic and facultative anaerobic bacteria. The results showed 11 rod shaped, Gram–positive and spore forming bacteria and 2 rod shaped, Gram–negative non-spore forming bacteria are isolated from spring and healing waters. The colonial and physiological characteristics of the isolated strains are defined. The biochemical profiles of the selected bacteria are determined with the system for rapid identification API 50 CH. The strains are identified by software processing of the obtained biochemical profiles with apiweb®. Furthermore, the tested strains are genetically identified by molecular-genetic methods – ARDRA analysis and sequencing of the gene for the 16S rRNA. The results obtained from the biochemical and molecular-genetic studies indicate that the selected strains belong to different species of genus Bacillus, Aeromonas, Klebsiella.&#x0D; The identification strains support for registration of water sources in Plovdiv region, Bulgaria according Decree No. 9.

The last pteraspids (Vertebrata, Heterostraci): new material from the Middle Devonian of Alberta and Idaho

AbstractThis report documents the last pteraspids, (armored, jawless members of the Heterostraci), which are otherwise only known from the Early Devonian of the Old Red Sandstone Continent. Tuberculate pteraspid heterostracans are described from the Middle Devonian beds of two formations in western North America. The late Givetian Yahatinda Formation of Alberta and British Columbia consists of channels cut into lower Paleozoic rocks and represents deposition in marine to littoral environments. Clavulaspis finis (Elliott et al., 2000a) new combination is redescribed from additional material from the Yahatinda Formation and reassigned to the new genus Clavulaspis because the original genus name is invalid. The Eifelian Spring Mountain beds of Idaho consist of a large channel that represents a clastic-dominated estuarine environment. It contains Scutellaspis wilsoni new genus new species, and the previously described species from the Spring Mountain beds is redescribed and reassigned to Ecphymaspis new genus, which was prompted by new material and a review of the validity of the original genus name. Phylogenetic analysis shows that these three new taxa form part of the derived clade Protaspididae.UUID: http://zoobank.org/9cf09b21-cec1-4ce4-bc2b-658d0b515e10

Conserve the eco-evolutionary dynamic, not the subspecies: phenological divergence and gene flow between temporal cohorts of Euphilotes ancilla endemic to southern Nevada

Euphilotes ancilla purpura and cryptica (Lycaenidae), butterflies endemic to the Spring Mountains (Clark Co., Nevada), have been described as two univoltine, temporally isolated, sympatric taxa that utilize different early- and late-flowering larval host plant varieties (Eriogonum umbellatum). However, our results from field and laboratory indicate that this is not the case. The subspecies overlap in timing of adult reproductive flight (compilation of field records 1977 to 2018) and laboratory emergence of adults from early-season, non-diapause pupae indicate butterflies are not univoltine. Genetic samples collected from putative E. a. purpura (Early cohort) and cryptica (Late cohort) subpopulations show no evidence of genetic structure indicative of allochronic isolation in phylogenies of 26 mitochondrial DNA COI haplotypes and 18 nuclear ITS1 alleles. Analysis of molecular variance revealed 89% of mitochondrial DNA variation structured within and among subpopulations, with only 11% between the purportedly isolated subspecies. Analysis of isolation and migration indicated gene flow from the Early to Late cohort was 3 × greater than in the opposite direction. We conclude that, rather than two separate subspecies, Euphilotes ancilla exists in a network of partially interconnected subpopulations extending from 1750 to 3000 m across much of the Spring Mountains. Gene flow is related to the timing of adult flight and host plant flowering, contributing to the genetic variation in phenology necessary for evolutionary tracking of shifting flowering periods of larval host plants. Maintenance of connectivity and gene flow across the Spring Mountains is therefore essential for population persistence of both cohorts in the face of environmental change.

Assessing the Impact of Executive Education

Harry Miller, the new CEO of a large and growing multinational transportation and logistics company, has asked Allison Freeman, his CHRO, to brief him on the impact that their off-site custom executive education program has had. In turn, the CHRO has enlisted Jack Drake, the program's faculty leader, to collaborate with her in responding to the CEO's request. Students are asked to step into the role of the faculty leader, who has formulated a general framework to do so, and must fill the framework with as many potential ideas regarding the impact as possible. Excerpt UVA-G-0650 Aug. 5, 2020 Assessing the Impact of Executive Education Introduction Jack Drake, a senior faculty member at the Gail Palmer Ashton Graduate School of Business and a frequent executive education custom program faculty leader for the school, distractedly looked at the caller ID and picked up his phone on the fifth ring. “Allison, hi, how are you?” Drake asked as his attention immediately shifted to Allison Freeman, CHRO at one of the school's largest executive education corporate clients, on the other end of the line. “I hope you are doing well and finding time to enjoy the arrival of spring,” Drake sincerely stated. “Hi, Jack, I'm glad that I caught you in the office, and yes, I had my first spring mountain biking trek this past weekend, and it felt really good to be out in the hills and woods. It even feels great today to have sore legs and arms from the pounding they took on those rugged trails.” . . .

Groundwater geochemistry and flow in the Spring Mountains, NV: Implications for the Death Valley Regional Flow System

Groundwater geochemistry and 87Sr/86Sr from spring waters in the Spring Mountains, NV were used to understand how groundwater recharging in the Spring Mountains influences regional groundwater flow in the Death Valley Regional Flow System (DVRFS). Previous researchers hypothesized that groundwater from the Spring Mountains contributes to the DVRFS, an interbasin groundwater flow system (IGF). However, the Spring Mountains are geologically heterogeneous, therefore, a uniform contribution of groundwater flow across the range is unlikely. Here, we use spring water geochemistry, spring water and host rock 87Sr/86Sr, and observations of the surrounding geology to determine what regions of the Spring Mountains are likely to contribute more flow to the DVRFS. Based on geochemical and isotopic evidence, Spring Mountains groundwater can be divided into three flow regions with distinct geochemical signals reflecting silicate or carbonate water-rock interactions and location relative to major thrust faults. The Keystone Thrust flow region (KST) has a 87Sr/86Sr of 0.710–0.711, is recharged by both rain and snow, and weathers both Mesozoic sandstones and Permian and Cambrian carbonate. Central Spring Mountains (CSM) groundwater has a 87Sr/86Sr of ~0.708, is primarily recharged by snow, and weathers Permian and Cambrian limestones and dolostones. The Montgomery Hills (MH) flow region has a 87Sr/86Sr 0.711–0.733, is recharged by both rain and snow, and weathers both Permian and Cambrian carbonates and Precambrian siliciclastics. Groundwater mixing between flow groups occurs along major thrust faults in the study area, as evidenced by 87Sr/86Sr signatures that reflect one flow group and δ18O and δ2H and geochemical signatures that reflect another flow group. The combination of geochemical and isotopic results suggest CSM groundwater is the most likely to reach Death Valley because CSM groundwater composition reflects the geochemical and isotopic signatures of the highly permeable rocks that connect the Spring Mountains to Death Valley. Flow leaving the KST and MH also influences the DVRFS after mixing with CSM groundwater along major thrust faults.

Practical Applications of Evidence That Analyst Forecasts Do Not Reflect Their Expectations

<h3>Practical Applications Summary</h3> In <b>Evidence That Analyst Forecasts Do Not Reflect Their Expectations</b>, published in the Winter 2018 issue of <b><i>The Journal of Investing</i></b>, <b>Haim Mozes</b> of <b>Spring Mountain Capital, LP</b>, presents a study of how the forecasting accuracy of sell-side analysts has changed over time, and concludes that analysts deliberately do not update their estimates with the best information as time gets closer to the earnings release date. While these findings are less relevant to investors with longer holding periods or investment horizons, they are very relevant to investors whose strategies rely on short-term trading around earnings surprises and the related market expectations. It has become more challenging to use analysts’ forecasts to determine what earnings expectations are already priced, and strategies based on exploiting earnings surprises have become more difficult to execute. Consequently, if investors cannot discern market expectations, they should forgo strategies based on short-term trading around earnings releases. <b>TOPICS:</b>Fundamental equity analysis, information providers/credit ratings, performance measurement

Subsidence history of the Ediacaran Johnnie Formation and related strata of southwest Laurentia: Implications for the age and duration of the Shuram isotopic excursion and animal evolution

The Johnnie Formation and associated Ediacaran strata in southwest Laurentia are ~3000 m thick, with a Marinoan cap carbonate sequence at the bottom, and a transition from Ediacaran to Cambrian fauna at the top. About halfway through the sequence, the Shuram negative carbon isotopic excursion occurs within the Rainstorm Member near the top of the Johnnie Formation, followed by a remarkable valley incision event. At its type locality in the northwest Spring Mountains, Nevada, the Johnnie lithostratigraphy consists of three distinctive sand-rich intervals alternating with four siltstone/carbonate-rich intervals, which appear correlative with other regional ­Johnnie Formation outcrops. Carbon isotope ratios in the sub–Rainstorm Member part of the Johnnie Formation are uniformly positive for at least 400 m below the Shuram excursion and compare well with sub–Shuram excursion profiles from the ­Khufai Formation in Oman. There is historical consensus that the Johnnie and overlying formations were deposited on a thermally subsiding passive margin. Following previous authors, we used Paleozoic horizons of known biostratigraphic age to define a time-dependent exponential sub­sidence model, and extrapolated the model back in time to estimate the ages of the Shuram excursion and other prominent Ediacaran horizons. The model suggests that the Shuram excursion occurred from 585 to 579 Ma, and that incision of the Rainstorm Member shelf occurred during the 579 Ma Gaskiers glaciation. It further suggests that the base of the Johnnie Formation is ca. 630 Ma, consistent with the underlying Noonday Formation representing a Marinoan cap carbonate sequence. Our results contrast with suggestions by previous workers that the Shuram excursion followed the Gaskiers event by some 20–30 m.y. We suggest instead that the Shuram and Gaskiers events were contemporaneous with the biostratigraphic transition from acantho­morphic to leiospherid acritarchs, and with the first appearance of widespread macroscopic animal life, 38 m.y. prior to the Ediacaran-Cambrian boundary.

Timing of exhumation, Wheeler Pass thrust sheet, southern Nevada and California: Late Jurassic to middle Cretaceous evolution of the southern Sevier fold-and-thrust belt

Zircon (U-Th)/He (ZHe) thermochronologic data for 46 samples from the Wheeler Pass thrust sheet, which carries thick passive-margin strata and is discontinuously exposed across the southern part of the Sevier fold-and-thrust belt, record Late Jurassic cooling related to exhumation during early thrust slip, and local middle Cretaceous cooling related to footwall basement imbrication. Within the frontal part of the Wheeler Pass sheet exposed in the northwest Spring Mountains, ZHe ages decrease from ca. 160 to 140 Ma over a paleodepth interval of ∼6 to 9 km in Devonian to Lower Cambrian strata, interpreted to record exhumation and enhanced cooling above a frontal ramp, followed by slow cooling. A similar pattern of ZHe ages occurs over a more limited paleodepth range exposed within the Resting Spring Range. To the south in the Nopah Range, ZHe ages of ca. 140 Ma in Lower Cambrian strata record early cooling, followed by slow cooling until ca. 100 Ma. ZHe ages in underlying Paleoproterozoic basement rocks decrease from ca. 100 to 85 Ma over a paleodepth interval of ∼9 to 12 km, interpreted to record uplift, exhumation, and cooling during footwall basement imbrication as slip was transferred eastward onto the Keystone thrust system. Late Jurassic slip on the Wheeler Pass thrust overlapped with deformation along the NW-trending East Sierran thrust system, early hinterland crustal thickening, and growth of the Sierra magmatic arc, and may have been correlative with early deformation in the Central Nevada thrust belt. Slip on the Wheeler Pass thrust preceded major slip on other thrust sheets that carried thick passive-margin strata in more northern parts of the Sevier belt, probably reflecting the influence of different initial widths and tapers of the passive-margin sedimentary wedge.

Characterization and phylogenetic analysis of complete mitochondrial genomes for two desert cyprinodontoid fishes, Empetrichthys latos and Crenichthys baileyi

The Pahrump poolfish (Empetrichthys latos) and White River springfish (Crenichthys baileyi) are small-bodied teleost fishes (order Cyprinodontiformes) endemic to the arid Great Basin and Mojave Desert regions of western North America. These taxa survive as small, isolated populations in remote streams and springs and evolved to tolerate extreme conditions of high temperature and low dissolved oxygen. Both species have experienced severe population declines over the last 50–60years that led to some subspecies being categorized with protected status under the U.S. Endangered Species Act. Here we report the first sequencing of the complete mitochondrial DNA genomes for both E. l. latos and the moapae subspecies of C. baileyi. Complete mitogenomes of 16,546bp nucleotides were obtained from two E. l. latos individuals collected from introduced populations at Spring Mountain Ranch State Park and Shoshone Ponds Natural Area, Nevada, USA, while a single mitogenome of 16,537bp was sequenced for C. b. moapae. The mitogenomes of both species contain 13 protein-encoding genes, twenty-two tRNAs, and two rRNAs (12S and 18S) following the syntenic arrangement typical of Actinopterygiian fish mitogenomes, as well as D-loop control regions of 858bp for E. latos and 842bp for C. baileyi moapae. The two E. latos individuals exhibited only 0.0181% nucleotide sequence divergence across the entire mitogenome, implying little intraspecific mtDNA genetic variation. Comparative phylogenetic analysis of the poolfish and springfish mitochondrial genomes to available mitogenomes of other Cyprinodontoid fishes confirmed the close relationship of these oviparous Empetrichthys and Crenichthys genera to the viviparous goodeid fishes of central Mexico, and showed the combined clade of these fishes to be a sister group to the Profundulidae killifishes. Despite several significant life history and morphological differences between the Empetrichthyinae and Goodienae, estimates of evolutionary genetic distances using two partial regions of mtDNA point to inclusion of the Empetrichthys and Crenichthys genera within the family Goodeidae along with the goodeid fishes of central Mexico.

Practical Applications of Hedge Fund Illiquidity, Age and Performance

The golden age of hedge funds may be over, according to Haim Mozes and John Launny Steffens of Spring Mountain Capital. Mozes and Steffens offer a critical new insight into how age and size factors affect hedge fund performance, demonstrating how an illiquidity premium is responsible for the deleterious effects of both factors. Mozes, who also teaches at Fordham University, and his Spring Mountain colleague Steffens show that not only do older funds and those experiencing recent inflows underperform their peers, but they also tend to have fewer illiquid investments in their portfolios “The truth is that the illiquidity premium is very hard to measure,” explains Mozes in this interview with Institutional Investor Journals. “I came across an insight from Andrew Lo that I intuitively recognized: the idea that you could estimate the extent to which a hedge fund holds illiquid assets by examining how strongly its returns are correlated,” he explains.

Reconstructing a cultural fire regime in the Pennsylvania Anthracite Region

Fire history reconstructions provide fire managers with valuable information regarding historical fire regime dynamics. Yet, in the Central Hardwood Forest Region (CHF), there is an absence of dendroecological studies where frequent wildfires have persisted into the twenty-first century. This study presents the first documented tree-ring reconstruction of fire history in the Pennsylvania anthracite coal-producing region. An approximately 150-year fire chronology was developed from fire-scarred pitch pine (Pinus rigida) and sassafras (Sassafras albidum) collected on Spring Mountain in Schuylkill County. Principal component analysis and k-means cluster analysis were used to identify four fire regime clusters based on interacting fire and non-fire parameters. Results indicate that fires occurred under a variety of moisture conditions and that a mid-twentieth century increase in fire activity on Spring Mountain was associated with the collapse of the regional anthracite industry and possibly amplified by the 1960s drought. Fires continue to burn on Spring Mountain in the twenty-first century, contrary to the dominant pattern of fire exclusion across the CHF. Future research needs are highlighted regarding historical fire regime dynamics and cultural ties to landscape burning in the Pennsylvania Anthracite Region.

Common Raven (Corvus corax) kleptoparasitism at a Golden Eagle (Aquila chyrsaetos) nest in southern Nevada

ABSTRACT.— The Common Raven (Corvus corax) is a ubiquitous species in the Mojave Desert of southern Nevada and California. From 5 to 24 May 2014, using remote trail cameras, we observed ravens repeatedly kleptoparasitizing food resources from the nest of a pair of Golden Eagles (Aquila chyrsaetos) in the Spring Mountains of southern Nevada. The ravens fed on nine (30%) of the 30 prey items delivered to the nest during the chick rearing period. Kleptoparasitic behavior by the ravens decreased as the eagle nestling matured to seven weeks of age, suggesting a narrow temporal window in which ravens can successfully engage in kleptoparasitic behavior at eagle nests. The observation of kleptoparasitism by Common Ravens at the nest suggests potential risks to young Golden Eagles from Common Ravens.

Where Lower Calcite Abundance Creates More Alteration: Enhanced Rock Matrix Diffusivity Induced by Preferential Dissolution

Fractured rocks are essential for flow, solute transport and energy production in geosystems. Existing studies on mineral reactions in fractured rocks mostly consider single mineral systems where reactions occur at the fracture wall without changing rock matrix properties. This work presents multicomponent reactive transport numerical experiments in a fractured rock from the Brady’s field, a geothermal reservoir at a depth of 1,396 m in the Hot Springs Mountains, Nevada. Initial porosity, permeability, mineral composition (quartz, clay, and calcite), and fracture geometry are based on microscopy characterization and X-ray tomography. The model was calibrated using a CO2-saturated water flooding experiment. Three numerical experiments were carried out with the same initial physical properties however different calcite content. Although total dissolved masses are similar among the three cases, abundant calcite (50% (v/v), calcite50) leads to a localized, thick zone of large porosity increase while low calci...

Ecology, distribution, and predictive occurrence modeling of Palmer’s chipmunk (Tamias palmeri): a high-elevation small mammal endemic to the Spring Mountains in southern Nevada, USA

Abstract Although montane sky islands surrounded by desert scrub and shrub steppe comprise a large part of the biological diversity of the Basin and Range Province of southwestern North America, comprehensive ecological and population demographic studies for high-elevation small mammals within these areas are rare. Here, we examine the ecology and population parameters of the Palmer’s chipmunk (Tamias palmeri) in the Spring Mountains of southern Nevada, and present a predictive GIS-based distribution and probability of occurrence model at both home range and geographic spatial scales. Logistic regression analyses and Akaike Information Criterion model selection found variables of forest type, slope, and distance to water sources as predictive of chipmunk occurrence at the geographic scale. At the home range scale, increasing population density, decreasing overstory canopy cover, and decreasing understory canopy cover contributed to increased survival rates.

Pseudouroctonus peccatum Tate et al., 2013, Rediscovered

Shortly after the discovery of Pseudouroctonus peccatum Tate, Riddle, Soleglad et Graham, 2013 (Scorpiones: Vaejovidae) there was a large wildfire in the Spring Mountains of Nevada. At the time the species description was published, it was noted that the only known population of this species may have been extirpated by the fire and subsequent flooding of the type locality habitat (Tate et al. 2013). Today it is certain that the species has survived after the collection of 12 new specimens. Additional data on males are also presented.