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At least 487 records · Page 27Linked to original sources

USGS2025

Climate and connectivity mediate overwintering habitat suitability for centrarchids in a large floodplain river network

Availability of suitable overwintering habitat is crucial for the survival of centrarchids in large floodplain rivers. However, there remains uncertainty in the spatiotemporal drivers of suitable conditions. We paired hydrogeomorphic characteristics with environmental data from 1994 to 2018 in individual lentic areas to (1) assess overwintering habitat availability throughout the Upper Mississippi River System using existing habitat suitability indices (HSIs) and (2) explore potential drivers of overall habitat suitability (HSI O ) and its components (dissolved oxygen, temperature, and flow). We found that flow velocities that exceeded suitable thresholds were independently responsible for 53% of nonsuitable habitats, and connectivity with lotic channels and river discharge increased velocity within lentic habitats. Additionally, colder winter conditions reduced water temperature, reducing availability of highly suitable habitat. Our results indicate that although warmer winters could increase the availability of highly suitable habitat for centrarchids, changes in flow regimes could lead to more connected areas becoming unsuitable. Our results provide critical information on factors that can be prioritized to manage centrarchid habitat, which is especially important in the context of uncertain future climate.

upper Mississippi River↗

USGS2008

Introduction to the U.S. Geological Survey National Water-Quality Assessment (NAWQA) of ground-water quality trends and comparison to other national programs

Assessment of temporal trends in national ground-water quality networks are rarely published in scientific journals. This is partly due to the fact that long-term data from these types of networks are uncommon and because many national monitoring networks are not driven by hypotheses that can be easily incorporated into scientific research. The U.S. Geological Survey (USGS) National Water-Quality Assessment Program (NAWQA) since 1991 has to date (2006) concentrated on occurrence of contaminants because sufficient data for trend analysis is only just becoming available. This paper introduces the first set of trend assessments from NAWQA and provides an assessment of the success of the program. On a national scale, nitrate concentrations in ground water have generally increased from 1988 to 2004, but trends in pesticide concentrations are less apparent. Regionally, the studies showed high nitrate concentrations and frequent pesticide detections are linked to agricultural use of fertilizers and pesticides. Most of these areas showed increases in nitrate concentration within the last decade, and these increases are associated with oxic-geochemical conditions and well-drained soils. The current NAWQA plan for collecting data to define trends needs to be constantly reevaluated to determine if the approach fulfills the expected outcome. To assist this evaluation, a comparison of NAWQA to other national ground-water quality programs was undertaken. The design and spatial extent of each national program depend on many factors, including current and long-term budgets, purpose of the program, size of the country, and diversity of aquifer types. Comparison of NAWQA to nine other national programs shows a great diversity in program designs, but indicates that different approaches can achieve similar and equally important goals. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Conference Paper↗

USGS1998

Rocky 7 prototype Mars rover field geology experiments: 1. Lavic Lake and Sunshine volcanic field, California

Experiments with the Rocky 7 rover were performed in the Mojave Desert to better understand how to conduct rover-based, long-distance (kilometers) geological traverses on Mars. The rover was equipped with stereo imaging systems for remote sensing science and hazard avoidance and 57 Fe Mössbauer and nuclear magnetic resonance spectrometers for in situ determination of mineralogy of unprepared rock and soil surfaces. Laboratory data were also obtained using the spectrometers and an X ray diffraction (XRD)/XRF instrument for unprepared samples collected from the rover sites. Simulated orbital and descent image data assembled for the test sites were found to be critical for assessing the geologic setting, formulating hypotheses to be tested with rover observations, planning traverses, locating the rover, and providing a regional context for interpretation of rover-based observations. Analyses of remote sensing and in situ observations acquired by the rover confirmed inferences made from orbital and simulated descent images that the Sunshine Volcanic Field is composed of basalt flows. Rover data confirmed the idea that Lavic Lake is a recharge playa and that an alluvial fan composed of sediments with felsic compositions has prograded onto the playa. Rover-based discoveries include the inference that the basalt flows are mantled with aeolian sediment and covered with a dense pavement of varnished basalt cobbles. Results demonstrate that the combination of rover remote sensing and in situ analytical observations will significantly increase our understanding of Mars and provide key connecting links between orbital and descent data and analyses of returned samples.

Journal of Geophysical Research E: Planets↗

USGS2002

Prioritizing conservation potential of arid-land montane natural springs and associated riparian areas

Using inventory data and input from natural resource professionals, we developed a classification system that categorizes conservation potential for montane natural springs. This system contains 18 classes based on the presence of a riparian patch, wetland species, surface water, and evidence of human activity. We measured physical and biological components of 276 montane springs in the Oscura Mountains above 1450 m and the San Andres Mountains above 1300 m in southern New Mexico. Two of the 18 classes were not represented during the inventory, indicating the system applies to conditions beyond the montane springs in our study area. The class type observed most often (73 springs) had a riparian patch, perennial surface water, and human evidence. We assessed our system in relation to 13 other wetland and riparian classification systems regarding approach, area of applicability, intended users, validation, ease of use, and examination of system response. Our classification can be used to rapidly assess priority of conservation potential for isolated riparian sites, especially springs, in arid landscapes. We recommend (1) including this classification in conservation planning, (2) removing deleterious structures from high-priority sites, and (3) assessing efficiency and use of this classification scheme elsewhere. ?? 2002 Elsevier Science Ltd.

Journal of Arid Environments↗

USGS1996

40Ar/39Ar geochronology and paleomagnetism of Independence volcano, Absaroka volcanic supergroup, Beartooth mountains, Montana

Independence volcano is a major volcanic complex in the lower part of the Absaroka Volcanic Supergroup (AVS) of Montana and Wyoming. Recently reported Rb–Sr mineral dates from the complex give apparent ages of 91 and 84 Ma, whereas field relationships and the physical and compositional similarity of the rocks with other dated parts of the AVS indicate an Early to Middle Eocene age for eruption and deposition. To resolve the conflict between age assignments based on stratigraphic correlations and Rb–Sr dates, we report new paleomagnetic data and 40 Ar/ 39 Ar dates for Independence volcano. Paleomagnetic data for the stock and an andesite plug that cuts the stock are well grouped, of reverse polarity, and yield a virtual geomagnetic pole that is essentially identical to Late Cretaceous and Tertiary reference poles. The reverse polarity indicates that the magnetization of these rocks is probably younger than the Cretaceous normal superchron, or less than about 83.5 Ma. Hornblende from a volcanic breccia near the base of the volcanic pile gives a 40 Ar/ 39 Ar age of 51.57 Ma, whereas biotites from a dacite sill and a granodiorite stock that forms the core of the volcano give dates that range from 49.96 to 48.50 Ma. These dates record the age of eruption and intrusion of these rocks and clearly show that the age of Independence volcano is Early to Middle Eocene, consistent with stratigraphic relations. We suggest that the Rb–Sr mineral dates from the Independence stock and related intrusions are unreliable.

Montana, Wyoming↗

USGS2010

Seasonal H2O and CO2 ice cycles at the Mars Phoenix landing site: 1. Prelanding CRISM and HiRISE observations

The condensation, evolution, and sublimation of seasonal water and carbon dioxide ices were characterized at the Mars Phoenix landing site from Martian northern midsummer to midspring (L s ∼ 142° – L s ∼ 60°) for the year prior to the Phoenix landing on 25 May 2008. Ice relative abundances and grain sizes were estimated using data from the Compact Reconnaissance Imaging Spectrometer for Mars and High Resolution Imaging Science Experiment aboard Mars Reconnaissance Orbiter and a nonlinear mixing model. Water ice first appeared at the Phoenix landing site during the afternoon in late summer (L s ∼ 167°) as an optically thin layer on top of soil. CO 2 ice appeared after the fall equinox. By late winter (L s ∼ 344°), the site was covered by relatively pure CO 2 ice (∼30 cm thick), with a small amount of ∼100 μ m diameter water ice and soil. As spring progressed, CO 2 ice grain sizes gradually decreased, a change interpreted to result from granulation during sublimation losses. The combined effect of CO 2 sublimation and decreasing H 2 O ice grain sizes allowed H 2 O ice to dominate spectra during the spring and significantly brightened the surface. CO 2 ice disappeared by early spring (L s ∼ 34°) and H 2 O ice by midspring (L s ∼ 59°). Spring defrosting was not uniform and occurred more rapidly over the centers of polygons and geomorphic units with relatively higher thermal inertia values.

Journal of Geophysical Research E: Planets↗

USGS2007

Mars reconnaissance orbiter's high resolution imaging science experiment (HiRISE)

The HiRISE camera features a 0.5 m diameter primary mirror, 12 m effective focal length, and a focal plane system that can acquire images containing up to 28 Gb (gigabits) of data in as little as 6 seconds. HiRISE will provide detailed images (0.25 to 1.3 m/pixel) covering ∼1% of the Martian surface during the 2‐year Primary Science Phase (PSP) beginning November 2006. Most images will include color data covering 20% of the potential field of view. A top priority is to acquire ∼1000 stereo pairs and apply precision geometric corrections to enable topographic measurements to better than 25 cm vertical precision. We expect to return more than 12 Tb of HiRISE data during the 2‐year PSP, and use pixel binning, conversion from 14 to 8 bit values, and a lossless compression system to increase coverage. HiRISE images are acquired via 14 CCD detectors, each with 2 output channels, and with multiple choices for pixel binning and number of Time Delay and Integration lines. HiRISE will support Mars exploration by locating and characterizing past, present, and future landing sites, unsuccessful landing sites, and past and potentially future rover traverses. We will investigate cratering, volcanism, tectonism, hydrology, sedimentary processes, stratigraphy, aeolian processes, mass wasting, landscape evolution, seasonal processes, climate change, spectrophotometry, glacial and periglacial processes, polar geology, and regolith properties. An Internet Web site (HiWeb) will enable anyone in the world to suggest HiRISE targets on Mars and to easily locate, view, and download HiRISE data products.

Journal of Geophysical Research E: Planets↗

USGS1986

U-Pb geochronology of two augen gneiss terranes, Idaho: New data and tectonic implications

U–Pb isotopic analyses of cogenetic zircon suites revise the ages of two augen gneiss terranes in central and northern Idaho. The augen gneiss of Priest River yields an upper-intercept concordia age for only moderately discordant zircons of 1576 ± 13 Ma; there is no evidence of an inherited xenocrystic lead component. Because this unit probably is in basement beneath Belt–Purcell strata, it provides a maximum age for Belt and Purcell sedimentation. However, high-grade metamorphism and structural complexity permit several tectonic interpretations, all of which should be treated with caution pending further detailed studies.Zircons from the augen gneiss of Red River contain inherited radiogenic lead, but by analogy with lithologically and isotopically similar augen gneiss and porphyritic granite near Salmon and Shoup, Idaho, an age of about 1370 Ma is suggested. However, the uncertainty associated with this value is unknown and could be large. Intrusion preceded or was synkinematic with at least part of the deformation and metamorphism that affected the metasedimentary host rocks, thought by some to be Belt–Purcell strata.

Idaho↗

USGS2021

Lake-wide annual status of Mysis diluviana population in Lake Michigan in 2015

Mysis diluviana is one of the most abundant zooplankton by biomass in the Laurentian Great Lakes of North America, a predator of other zooplankton and an important prey for fishes. Studies of long-term trends in Lake Michigan have shown 2005–2016 densities to be 50–80% lower than 1990s densities, but these observations have been based on annual monitoring that is either spatially or seasonally limited. We combined Lake Michigan Mysis data from three annual programs and the 2015 Cooperative Science and Monitoring Initiative to achieve broad spatial coverage during spring, summer, and fall of 2015 and broad depth coverage during spring 2016. Lake-wide, annual density and biomass were 82 (SE: 10) Mysis /m 2 and 200 (SE: 36) mg dry mass/m 2 . Density and biomass estimates were highest offshore, generally higher in the north basin, and seasonally highest in summer. Annual lake-wide averages for depths >30 m were better captured by seasonally-extensive annual programs than spatially-extensive annual programs, although spring sampling may bias annual values low. Mysis cohorts grew 0.026 mm/d (age-0) and 0.007 to 0.027 mm/d (age-1). Annual mortality was 81–98%. Reproduction was fall-spring and seasonal lake-wide estimates ranged from 0.6 to 19.1% females brooding, 13–20 embryos/brood, and 3–46 embryos/m 2 . Annual production (423 mg dry mass/m 2 /yr, SE: 31) was lower than all but one previous estimate from lakes Michigan, Huron, and Ontario. While Mysis tend to persist, low Mysis production may be a concern for prey fishes that feed on Mysis .

Lake Michigan↗

USGS2020

The chemostratigraphy of the Murray formation and role of diagenesis at Vera Rubin ridge in Gale crater, Mars, as observed by the ChemCam instrument

Geochemical results are presented from Curiosity’s exploration of the Vera Rubin ridge (VRR), in addition to the full chemostratigraphy of the predominantly lacustrine mudstone Murray formation up to and including VRR. VRR is a prominent ridge flanking Aeolis Mons (informally Mt. Sharp), the central mound in Gale crater, Mars, and was a key area of interest for the Mars Science Laboratory mission. ChemCam data show that VRR is overall geochemically similar to lower-lying members of the Murray formation, even though the top of VRR is characterized by strong hematite spectral signatures as observed from orbit. While overall geochemically similar, VRR is characterized by a prominent decrease in Li abundance and Chemical Index of Alteration across the ridge. This decrease follows the morphology of the ridge rather than elevation and is inferred to reflect a non-depositionally controlled decrease in clay mineral abundance in VRR rocks. Additionally, a notable enrichment in Mn above baseline levels is observed on VRR. While not supporting a single model, the results suggest that VRR rocks were likely affected by multiple episodes of post-depositional groundwater interactions that made them more erosionally resistant than surrounding Murray rocks – thus resulting in the modern-day ridge after subsequent erosion.

Journal of Geophysical Research: Planets↗

USGS2014

Evaluating the predictive performance of empirical estimators of natural mortality rate using information on over 200 fish species

Many methods have been developed in the last 70 years to predict the natural mortality rate, M , of a stock based on empirical evidence from comparative life history studies. These indirect or empirical methods are used in most stock assessments to (i) obtain estimates of M in the absence of direct information, (ii) check on the reasonableness of a direct estimate of M , (iii) examine the range of plausible M estimates for the stock under consideration, and (iv) define prior distributions for Bayesian analyses. The two most cited empirical methods have appeared in the literature over 2500 times to date. Despite the importance of these methods, there is no consensus in the literature on how well these methods work in terms of prediction error or how their performance may be ranked. We evaluate estimators based on various combinations of maximum age ( t max ), growth parameters, and water temperature by seeing how well they reproduce >200 independent, direct estimates of M . We use tenfold cross-validation to estimate the prediction error of the estimators and to rank their performance. With updated and carefully reviewed data, we conclude that a t max -based estimator performs the best among all estimators evaluated. The t max -based estimators in turn perform better than the Alverson–Carney method based on t max and the von Bertalanffy K coefficient, Pauly’s method based on growth parameters and water temperature and methods based just on K . It is possible to combine two independent methods by computing a weighted mean but the improvement over the t max -based methods is slight. Based on cross-validation prediction error, model residual patterns, model parsimony, and biological considerations, we recommend the use of a t max -based estimator ( M = 4.899 t max − 0.916 "> M = 4.899 t − 0.916 max M=4.899tmax−0.916 , prediction error = 0.32) when possible and a growth-based method ( M = 4.118 K 0.73 L ∞ − 0.33 "> M = 4.118 K 0.73 L − 0.33 ∞ M=4.118K0.73L∞−0.33 , prediction error = 0.6, length in cm) otherwise.

ICES Journal of Marine Science↗

USGS2025

Elevation mediates juvenile steelhead demographic response to stream temperature and flow

Climate change alters streams by modifying flow dynamics, temperature, and biotic communities, changing the habitat where stream dwelling fish have evolved. We used snorkel survey data spanning four decades to investigate how juvenile steelhead (anadromous Oncorhynchus mykiss ) counts and size structure were influenced by stream temperature and flow. Warmer temperatures were associated with lower abundance and larger fish at low elevations and with higher abundance and smaller fish at higher elevations. Low flows were related to increased abundance and smaller fish at low elevations but to decreased abundance at high elevations, suggesting that lower elevation streams, which tend to be larger, provided additional habitat during low flows. High flows were negatively related to abundance and positively related to average size, suggesting emigration of fish in younger age-classes. Overall, steelhead exhibited greater resilience to warm temperatures at high elevations and, conversely, greater resilience to low and high flows at lower elevations. Understanding how streamflow and temperature affect juvenile steelhead abundance and size structure provides insight into how climate change can affect juvenile steelhead production.

Idaho↗

USGS2012

Evaluating a fish monitoring protocol using state-space hierarchical models

Using data collected from three river reaches in Montana, we evaluated our ability to detect population trends and predict fish future fish abundance. Data were collected as part of a long-term monitoring program conducted by Montana Fish, Wildlife and Parks to primarily estimate rainbow (Oncorhynchus mykiss) and brown trout (Salmo trutta) abundance in numerous rivers across Montana. We used a hierarchical Bayesian mark-recapture model to estimate fish abundance over time in each of the three river reaches. We then fit a state-space Gompertz model to estimate current trends and future fish populations. Density dependent effects were detected in 1 of the 6 fish populations. Predictions of future fish populations displayed wide credible intervals. Our simulations indicated that given the observed variation in the abundance estimates, the probability of detecting a 30% decline in fish populations over a five-year period was less than 50%. We recommend a monitoring program that is closely tied to management objectives and reflects the precision necessary to make informed management decisions.

Montana↗

USGS1999

Digital mapping of the Mars Pathfinder landing site: Design, acquisition, and derivation of cartographic products for science applications

The Imager for Mars Pathfinder (IMP) acquired more than 16,000 images and provided panoramic views of the surface of Mars at the Mars Pathfinder landing site in Ares Vallis. This paper describes the stereoscopic, multispectral IMP imaging sequences and focuses on their use for digital mapping of the landing site and for deriving cartographic products to support science applications of these data. Two‐dimensional cartographic processing of IMP data, as performed via techniques and specialized software developed for ISIS (the U.S. Geological Survey image processing software package), is emphasized. Cartographic processing of IMP data includes ingestion, radiometric correction, establishment of geometric control, coregistration of multiple bands, reprojection, and mosaicking. Photogrammetric processing, an integral part of this cartographic work which utilizes the three‐dimensional character of the IMP data, supplements standard processing with geometric control and topographic information [ Kirk et al. , this issue]. Both cartographic and photogrammetric processing are required for producing seamless image mosaics and for coregistering the multispectral IMP data. Final, controlled IMP cartographic products include spectral cubes, panoramic (360° azimuthal coverage) and planimetric (top view) maps, and topographic data, to be archived on four CD‐ROM volumes. Uncontrolled and semicontrolled versions of these products were used to support geologic characterization of the landing site during the nominal and extended missions. Controlled products have allowed determination of the topography of the landing site and environs out to ∼60 m, and these data have been used to unravel the history of large‐ and small‐scale geologic processes which shaped the observed landing site. We conclude by summarizing several lessons learned from cartographic processing of IMP data.

Journal of Geophysical Research E: Planets↗

USGS2020

Between the supercontinents: Mesoproterozoic Deer Trail Group, an intermediate age unit between the Mesoproterozoic Belt–Purcell Supergroup and the Neoproterozoic Windermere Supergroup in northeastern Washington, USA

Mesoproterozoic and Neoproterozoic basins in western North America record the evolving position of the Laurentian craton within two supercontinents during their growth and dismemberment: Columbia (Nuna) and Rodinia. The western-most exposures of the Columbia rift-related Belt–Purcell Supergroup are preserved in northeastern Washington, structurally overlain by the Deer Trail Group and depositionally overlying the Neoproterozoic Windermere Supergroup. It has been disputed whether the Deer Trail Group is correlative with the Belt–Purcell Supergroup, or younger. To help resolve the uncertain correlation of these units and their bearing on supercontinent evolution, we characterized the detrital zircon age populations of units from the Deer Trail Group, the Windermere Supergroup, and the Belt–Purcell Supergroup in northeastern Washington. These data show that the western part of the Columbia supercontinent (now located in Australia and eastern Antarctica) remained attached to western Laurentia and continued to supply 1600–1500 Ma detrital zircon grains to the Belt–Purcell Supergroup until after ca. 1391 Ma. The Deer Trail Group is younger than the Belt–Purcell strata, with the basal unit younger than ca. 1362 Ma and a middle unit younger than ca. 1300 Ma. The Deer Trail Group has a pre-Grenville-age provenance from the southwestern USA and possibly east Antarctica. The Buffalo Hump Formation is younger than the Deer Trail Group, with Grenville-age (ca. 1112 Ma) detrital zircon grains and a detrital zircon signature like that of the overlying Neoproterozoic Windermere Supergroup. We interpret the Deer Trail Group to have been deposited during the rift-demise of supercontinent Columbia and before the Grenville-age assembly of the supercontinent Rodinia.

Washington↗

USGS2026

Thermal detectability of subsurface water ice on Mars: A comparative analysis for the Subsurface Water Ice Mapping (SWIM) Project

We have developed a new global map of shallow ground ice distribution, SWIM23, based on Mars Global Surveyor Thermal Emission Spectrometer data and made systematic comparisons between this new map and two similar, previously developed data products. We have explored the origin of differences between the three ice maps by detailing technical and procedural differences in their development, by making global pixel-by-pixel comparisons, and by carrying out a series of one-dimensional thermal simulations to explore fundamental physical limitations of thermal ice-detection techniques. These efforts and the production of a composite thermal ice-consistency map supported integration of multiple geophysical data products relevant to ice detection in the upper meter of the Martian regolith into the larger Mars Subsurface Water Ice Mapping project. Our work also highlights fundamental physical limitations to thermal ice detection as a technique, particularly the rapid fall-off in ice detection sensitivity at depths >30 cm, which produces maximum uncertainty in the presence and depth of ice within regions preferred for potential human landing sites. A future Mars orbiter mission designed to detect ice and support crewed landing site selection in the midlatitude region should give payload priority to an instrument capable of probing the 1–5 m depth range (i.e., a high-frequency radar), over a next-generation thermal spectrometer, which is unlikely to offer clarity on ice table depths or lateral continuity of the ice table in the locations of highest interest.

Planetary Science Journal↗

USGS2021

South Africa's experimental fisheries closures and recovery of the endangered African penguin

In a scientifically-transformative project, South Africa implemented a decade-long field experiment to understand how fisheries may be affecting its most iconic seabird, the African penguin Spheniscus demersus. This unique effort prohibits the take of anchovy and sardine within relatively small areas around four African penguin breeding colonies, two in the Benguela upwelling ecosystem and two in the adjacent Agulhas region. For the Benguela, fisheries closures within the birds’ primary foraging range increased their breeding productivity and perhaps reduced parental foraging efforts, indicating that the fisheries are competing with the birds for food. Results were less clear for foraging behaviour in the Agulhas, but no data on breeding success were collected there. The African penguin is endangered, its population continues to decline, and fisheries closures have been demonstrated to improve demographic traits that contribute to population growth. Therefore, given the critical status of the species, fisheries closures should be maintained, at least at Dassen Island where the population has great capacity to expand and support other nearby colonies. Continuing or implementing corresponding fisheries closures in the Agulhas region is also warranted, as well as creating and testing the value of pelagic closed areas during the non-breeding season when the penguins disperse widely across these ecosystems. These management actions would increase penguin food supplies and may help to meet societal goals of halting the decline of the penguin population, as well as maintaining the economic and cultural services provided by fisheries and ecotourism.

Agulhas, Benguela, Dassen Island↗

USGS2024

Trophic ecology of juvenile lean and siscowet lake charr (Salvelinus namaycush) in Lake Superior: Assessing for potential competition

We investigated the spatial overlap, diet, isotopic niche, and growth of juvenile lean and siscowet lake charr ( Salvelinus namaycush ) in Lake Superior to address concerns of potential competition with implications to the study of resource polymorphism. Catch data revealed the greatest levels of sympatry in waters from 40 to 60 m. Juvenile lean and siscowet diet changed ontogenetically with Mysis being the dominant prey item for the smallest lake charr but differentiating with onset of piscivory. As ecotypes increased in size, lean diets became dominated by pelagic prey, whereas siscowets had equal proportions of benthic and pelagic prey. Isotopic niche overlap declined between ecotypes coincident with siscowet lake charr shifting to deeper habitats around 400 mm. Lean and siscowet exhibited different growth trajectories. However, length at age-4 declined in parallel for both ecotypes with no trend in condition suggesting that lake charr growth is sensitive to prey biomass and unlikely related to competition. Our findings indicate minimal evidence of competition and support the concept that multiple sympatric ecotypes of lake charr in Lake Superior are maintained by resource polymorphism.

Lake Superior↗