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During the last glacial maximum (LGM), the western Uinta Mountains of northeastern Utah were occupied by the Western Uinta Ice Field. Cosmogenic Be-10 surface-exposure ages from the terminal moraine in the North Fork Provo Valley and paired Al-26 and Be-10 ages from striated bedrock at Bald Mountain Pass set limits on the timing of the local LGM. Moraine boulder ages suggest that ice reached its maximum extent by 17.4 +/- 0.5 ka (+/- 2 sigma). Be-10 and Al-26 measurements on striated bedrock from Bald Mountain Pass, situated near the former center of the ice field, yield a mean Al-26/Be-10 ratio of 5.7 +/- 0.8 and a mean exposure age of 14.0 +/- 0.5 ka, which places a minimum-limiting age on when the ice field melted...
This study provides a detailed pedogenic evaluation of two Upper Triassic (Late Norian through Rhaetian) stratigraphic intervals in New Mexico in order to assess the climate and ecology of the Latest Triassic, which ended in a mass extinction. The two study areas are located in north?central and east-central New Mexico and are separated by 200 km. Each section contains abundant paleosols of varying maturity with features that reflect an arid to semiarid climate. There is little pedogenic variation throughout the strata at each location, and a typical paleosol profile is about 1 m thick and has an AB?Bw?Bk?BC horizon succession. Bkm, Bss, Bssk, or Bssg horizons are present in some paleosols. Micromorphological features...
Reconstructing climates of the past relies on a variety of evidence from a large number of sites to capture the varied features of climate and the spatial heterogeneity of climate change. This review summarizes available information from diverse Holocene paleoenvironmental records across eastern Beringia (Alaska, westernmost Canada and adjacent seas), and it quantifies the primary trends of temperature- and moisture-sensitive records based in part on midges, pollen, and biogeochemical indicators (compiled in the recently published Arctic Holocene database, and updated here to v2.1). The composite time series from these proxy records are compared with new summaries of mountain-glacier and lake-level fluctuations,...
Clastic and organic sediments exposed in two stream cutbanks above modern timberline in the headwaters of the Henrys Fork drainage record multiple episodes of fluvial, lacustrine and wetland deposition. The location of the upper Henrys Fork at the boundary between modern summer-wet/winter-dry and summer dry/winter-wet precipitation regimes suggests that changes in vegetation during the Holocene were due primarily to variations in growing-season temperature. A radiocarbon date of 9310 6 70 BP on a Salix fragment from the base of one exposure indicates that the upper reaches of the Henrys Fork were vegetated by riparian willows by the early Holocene. Four other dates on wood and bulk organics ranging up to 4070 6...
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Great thicknesses of eolian dune deposits of early Oligocene age crop out in the Chuska Mountains of northwestern New Mexico-Arizona (as much as 535 m thick) and in the Mogollon-Datil volcanic field of western New Mexico-Arizona (as much as 300 m thick). 40Ar/39Ar ages of intercalated volcanic rocks indicate eolian deposition in these areas was approximately synchronous, with eolian accumulation beginning regionally at ca. 33.5 Ma and ending at ca. 27 Ma. Probable eolian sandstone of Oligocene age 483 m thick is also present in the subsurface of the Albuquerque Basin of the Rio Grande rift. The beginning of eolian deposition on the Colorado Plateau corresponds closely to the beginning of eolian (loessic) deposition...
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The late Pleistocene was a climatically dynamic period, with abrupt shifts between cool-wet and warm-dry conditions. Increased effective precipitation supported large pluvial lakes and long-lived spring ecosystems in valleys and basins throughout the western and southwestern U.S., but the source and seasonality of the precipitation are debated. Here we present stable carbon and oxygen isotope data from tooth enamel of late Pleistocene herbivores recovered from paleowetland deposits at Tule Spring Fossil Beds National Monument in the Las Vegas Valley of southern Nevada, as well as modern herbivores from the surrounding area, to investigate whether winter or summer precipitation was responsible for driving the wet...
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PRISM3D uses multiple proxies to develop February and August synoptic reconstructions of the surface ocean. Planktonic foraminiferal assemblages were translated to February and August surface temperatures via factor analytic transfer function and the modern analog technique. Mg/Ca and alkenone paleothermometry were incorporated as supplementary data for the first time in a PRISM reconstruction. Individual time series were calibrated to age using a combination of magnetobioisostratigraphy, and warm peaks within the PRISM interval were averaged.These warm peak averages for February and August form the basic data used to produce contour maps of mid-Pliocene SST. Wherever other proxy data were available, they were plotted...
Reconstructing climates of the past relies on a variety of evidence from a large number of sites to capture the varied features of climate and the spatial heterogeneity of climate change. This review summarizes available information from diverse Holocene paleoenvironmental records across eastern Beringia (Alaska, westernmost Canada and adjacent seas), and it quantifies the primary trends of temperature- and moisture-sensitive records based in part on midges, pollen, and biogeochemical indicators (compiled in the recently published Arctic Holocene database, and updated here to v2.1). The composite time series from these proxy records are compared with new summaries of mountain-glacier and lake-level fluctuations,...
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The elevation history of Earth's surface is key to understanding the geodynamic processes responsible for the rise of plateaus. We investigate the timing of Colorado Plateau uplift by estimating depositional temperatures of Tertiary lake sediments that blanket the plateau interior and adjacent lowlands using carbonate clumped isotope paleothermometry (a measure of the temperature-dependent enrichment of 13C-18O bonds in carbonates). Comparison of modern and ancient samples deposited near sea level provides an opportunity to quantify the influence of climate and therefore assess the contribution of changes in elevation to the variations of surface temperature on the plateau. Analysis of modern lake calcite from 350...
Understanding and modeling precipitation isotope (?18O and ?D) patterns for large regions of the globe requires quantifying processes governing continental-scale climatology and hydrology. In this study, we have evaluated the extent to which inclusion of monthly moisture source temperature and moisture source locations in the Rayleigh distillation model aid in reproducing the relationships between monthly time series of precipitation isotope (?18O) values and temperature across the contiguous United States. The steepest isotope-temperature slopes (0.5??0.6? ?18O/�C) and greatest ?18O value correlations with temperature (r2 = 0.5?0.8), derived from 5 continuous years of the data from the United States Network for...
PlioMIP is a network of paleoclimate modelers and geoscientists who, through the study of Pliocene warm periods, seek to understand the sensitivity of the climate system to forcings and examine how well models reproduce past climate change. Participants at the PlioMIP2 meeting at the British Antarctic Survey in Cambridge November 2018
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In the past century, eruptions of Steamboat Geyser in Yellowstone’s Norris Geyser Basin were mainly clustered in three episodes: between 1961 and 1969, between 1982 and 1984, and in a sequence of eruptions that began in 2018 (Reed et al., 2021) and resulted in extensive damage to, and mortality of the surrounding trees. To characterize tree response to geyser activity over time, and the response of geyser activity to climate variability, aerial and ground imagery were analyzed to document changes in tree coverage around the geyser since 1954. Twenty samples of silicified tree remnants were collected from near the geyser vent for radiocarbon (14C) dating to determine if trees grew during periods when the geyser was...
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The Colorado River is a crucial water source for millions of people in the Southwest. Warming temperatures, clearly documented in climate records for the Colorado River basin, are having an impact on the amount of annual streamflow yielded from rain and snow. Recent work has revealed that warming temperatures have played an increasingly important role over the past decades, both exacerbating droughts and dampening the effects of wet winters on high stream flows. Understanding and anticipating how warming temperatures will influence future water supply in the Colorado River basin is increasingly important for resource management, particularly in light of recent drought conditions. The overarching goals of this...
The Salt Lake City, Utah, region has a climate record dating from the mid-1800s that can be used to calibrate a tree ring record to climate and streamflows. A number of good candidate species for tree ring analysis include indigenous coniferous species that are signature species in tree ring analysis because their growth is sensitive to drought. However, these species represent different habitats. We will conduct controlled field studies to define the relationship between a suite of tree species native to the Wasatch range and drought stress and air temperature as well as to use tree ring data to understand and explain paleoclimate drought cycles and reconstruct streamflows in an innovative way. The research...
The Colorado River has historically been an abundant source of supply for water users in the United States and Mexico. With growth of demands on this water supply, the time of historical abundance has ended. The previous five years of drought remain manifested in low reservoir levels. The Secretary of the Interior is beginning preparation of first-ever shortage criteria for the reservoir system. These conditions demonstrate the need for a strong scientific foundation in understanding climatic and hydrologic conditions that influence Colorado River water supplies. We know that droughts will inevitably occur in the future – a future made more uncertain by the impacts of climate change and increased hydrologic variability....
A quarry within the Cedar Mountain Formation in Mussentuchit Wash, Emery County, Utah, produced a fossil assemblage containing the remains of at least eight juvenile iguanodontid dinosaurs (Eolambia caroljonesa). The Cedar Mountain Formation lies stratigraphically between the Tithonian?Berriasian (Upper Jurassic) Brushy Basin Member of the Morrison Formation and the Cenomanian (Upper Cretaceous) Dakota Formation. Detailed stratigraphic, sedimentological, geochronological, palynological, and paleontological data have been collected along a measured section at the site of the Cifelli #2 Eolambia caroljonesa Quarry. These data provide a chronostratigraphic and a biostratigraphic framework for the Cedar Mountain Formation...
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By collaborating with water managers and combining climate modeling and paleoclimate methods, the project team will incorporate prediction tools to assess risk of extreme wet/dry climate conditions for the next 10-15 years (i.e. decadal prediction). Our target area is the Wasatch Range Metropolitan Area that includes Salt Lake City one of the largest population centers within the Southern Rockies LCC. We will focus on projecting future water availability and quality with a specific goal for decadal prediction. The project team has partnered with numerous water agencies in the Wasatch Range who have made in-kind contributions towards this project. This partnership guarantees that the results will be disseminated,...
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In upland areas of Canyonlands National Park, Utah, thin deposits and paleosols show late Quaternary episodes of eolian sedimentation, pedogenesis, and climate change. Interpretation of the stratigraphy and optically stimulated luminescence ages of eolian and nearby alluvial deposits, their pollen, and intercalated paleosols yields the following history: (1) Eolian deposition at ca. 46 ka, followed by several episodes of alluviation from some time before ca. 40 ka until after 16 ka (calibrated). (2) Eolian deposition from ca. 17 ka to 12 ka, interrupted by periods of pedogenesis, coinciding with late Pleistocene alluviation as local climate became warmer and wetter. (3) A wetter period from 12 to 8.5 ka corresponding...
map background search result map search result map Influence of climate change and uplift on Colorado Plateau paleotemperatures from carbonate clumped isotope thermometry Late Quaternary eolian and alluvial response to paleoclimate, Canyonlands, southeastern Utah Back to the Future: Innovative Tree Ring Analysis to Reconstruct Paleoclimate and Streamflows for Improved Urban Water Planning Under Climate Change - BOR Project, FY2011 The Chuska erg: Paleogeomorphic and paleoclimatic implications of an Oligocene sand sea on the Colorado Plateau WaterSMART: Building Decadal Prediction of Extreme Climate for Managing Water Supply in Intermountain West Anticipating Future Impacts of Temperature on Streamflow in the Colorado River Basin Data release for Seasonality of precipitation in the southwestern United States during the late Pleistocene inferred from stable isotopes in herbivore tooth enamel Radiocarbon dating of silicified wood from around Steamboat Geyser in Norris Geyser Basin, Yellowstone National Park, 2021-2022 Late Quaternary eolian and alluvial response to paleoclimate, Canyonlands, southeastern Utah The Chuska erg: Paleogeomorphic and paleoclimatic implications of an Oligocene sand sea on the Colorado Plateau Data release for Seasonality of precipitation in the southwestern United States during the late Pleistocene inferred from stable isotopes in herbivore tooth enamel WaterSMART: Building Decadal Prediction of Extreme Climate for Managing Water Supply in Intermountain West Influence of climate change and uplift on Colorado Plateau paleotemperatures from carbonate clumped isotope thermometry Anticipating Future Impacts of Temperature on Streamflow in the Colorado River Basin