Green River overlook, Island in the Sky District, Canyonlands National Park, southeastern Utah

Driving Utah's Rivers: Working Water in the West

Apportionment of sulfur oxides at Canyonlands during the winter of 1990—III. Source apportionment of SO x, and sulfate and the conversion of S0 2 to sulfate in the Green River Basin

The White Rim Sandstone of Leonardian age forms prominent topographic benches west of the Colorado River in Canyonlands National Park. Its origin has been interpreted as eolian or marginal marine by various authors without specific evidence other than the large-scale cross-stratification which is generally conspicuous. A detailed study of the gross geometry, cross-stratification, ripple marks, trace fossils, and facies relations of the sandstone revealed a subaqueous environment of deposition which was probably sub-littoral marine. The formation contains numerous offshore bars that were constructed by surf and longshore currents moving from the northwest as shown by bar trends and cross-stratification analyses. Numerous small bars with 10-20 feet of relief occur in a northwesterly trending swarm northeast of Elaterite basin near the Green River. A larger elongate bar with 200 feet of relief extends in an arcuate northwesterly direction for about 10 miles through Elaterite basin. Excellent exposures of sedimentary structures reveal that the original geometric configuration of the bar is preserved. Th sandstone grades abruptly into fine-grained lagoonal redbeds just east of the Elaterite bar, forming a stratigraphic oil trap that has been exposed by Recent erosion. The shallow-water bar apparently was constructed on the nose of the Monument upwarp which was mildly positive, providing shoal conditions at the time of sedimentation. Pre-Triassic (Hoskinnini?) redbeds were deposited across the White Rim Sandstone, draping over the bars preserved at its upper surface. Subsequent erosion prior to Moenkopi (Triassic) sedimentation produced local angular unconformities along the margins of the bars. End_of_Article - Last_Page 453------------

Hydrologic stress is increasing in Fremont cottonwood (Populus fremontii) forests across the southwestern United States because of increased temperature and streamflow diversion. The spatial variability of this stress is large yet poorly understood. Along the Yampa and Green Rivers in Colorado and Utah, vapour pressure deficit and flow diversions increase downstream. To investigate effects of this gradient on cottonwoods, we measured the percent live canopy and height of randomly selected trees at three sites: Deerlodge Park on the Yampa River (DLP), Island Park on the upper Green (ILP) and Canyonlands National Park on the lower Green (CAN). From these same trees, we took increment cores to understand differences in tree growth in each forest over time. We then related tree metrics to local water availability, streamflow and climatic data. Cottonwoods at CAN were shorter and had lower percent live canopy and growth rate than similarly aged trees upstream. CAN trees that grew higher above the water surface also tended to have lower tree growth, height and live canopy percentage. Furthermore, the correlation between tree growth and maximum vapour pressure deficit showed a much stronger negative shift since 1990 at CAN than at the other sites. All of these differences suggest higher hydrologic stress at CAN, which we attribute to the combined effects of peak flow declines from Flaming Gorge Reservoir, flow diversion and the higher and increasing vapour pressure deficit at CAN. Further research on the variability of hydrologic stress on cottonwoods could help managers anticipate and mitigate the effects of drought stress in these iconic forests.

The roles of flood magnitude and duration in controlling channel width and complexity on the Green River in Canyonlands, Utah, USA

Tamarisk, a shrub or low tree that was artificially introduced into the American Southwest in the late 1800s, has spread throughout the Colorado Plateau region by occupying islands, sand bars, and beaches along streams. Historical photographs show that tamarisk spread from northern Arizona to the upper reaches of the Colorado and Green Rivers at a rate of about 20 km/yr. Detailed studies on the Green River in Canyonlands National Park, Utah, show that the plant has trapped and stabilized sediment, causing an average reduction in channel width of 27%. Photogrammetric analysis of historical ground photography, including photos from John Wesley Powell9s 1871 expedition, and recent aerial photographs supplemented by field surveys provided quantitative data. Expanded islands and channel-side bars exhibit allometric relationships as they change, apparently maintaining a balance between turbulence and friction. Overbank flooding is common on the tamarisk-stabilized features.

The cold deserts of the Colorado Plateau contain numerous geologically and geochemically distinct sedimentary bedrock types. In the area near Canyonlands National Park in Southeastern Utah, geochemical variation in geologic substrates is related to the depositional environment with higher concentrations of Fe, Al, P, K, and Mg in sediments deposited in alluvial or marine environments and lower concentrations in bedrock derived from eolian sand dunes. Availability of soil nutrients to vegetation is also controlled by the formation of secondary minerals, particularly for P and Ca availability, which, in some geologic settings, appears closely related to variation of CaCO3 and Ca-phosphates in soils. However, the results of this study also indicate that P content is related to bedrock and soil Fe and Al content suggesting that the deposition history of the bedrock and the presence of P-bearing Fe and Al minerals, is important to contemporary P cycling in this region. The relation between bedrock type and exchangeable Mg and K is less clear-cut, despite large variation in bedrock concentrations of these elements. We examined soil nutrient concentrations and foliar nutrient concentration of grasses, shrubs, conifers, and forbs in four geochemically distinct field sites. All four of the functional plant groups had similar proportional responses to variation in soil nutrient availability despite large absolute differences in foliar nutrient concentrations and stoichiometry across species. Foliar P concentration (normalized to N) in particular showed relatively small variation across different geochemical settings despite large variation in soil P availability in these study sites. The limited foliar variation in bedrock-derived nutrients suggests that the dominant plant species in this dryland setting have a remarkably strong capacity to maintain foliar chemistry ratios despite large underlying differences in soil nutrient availability.

Apportionment of sulfur oxides at canyonlands during the winter of 1990—I. study design and particulate chemical composition

We sampled the aquatic benthos at 6 remote sites on the Colorado and Green rivers through Canyonlands National Park, Utah, USA. This study provides the first published description of benthic standing mass, invertebrate community composition, and primary carbon source for this portion of the Colorado River system. High suspended sediment concentrations prohibited growth of primary producers. The primary carbon source for benthic invertebrates was terrestrial organic matter. The invertebrate community was composed of 49 taxa, mostly mayflies, caddisflies, and diptera, which were dominated by filterer/collector species. A smaller portion of the community was made up of predatory stoneflies and odonates. Standing mass of invertebrates on cobble substrates within a given site was stable over the multiyear sample period (1993 through 1996) and was comparable with other southwestern streams (overall mean = 0.41 g/m2 ash-free dry mass ± 0.01 SE). Invertebrate standing mass at each site was controlled by the availability of primary carbon. Primary carbon availability was controlled by supply to the site and retention within the site. Both aspects might be influenced by anthropogenic alteration of the river basin and discharge patterns upstream of the study site.

The cover photograph by Jacqueline E. Hunton for the January 1988 (v. 72) AAPG Bulletin should have read: Rim Trail, Island in the Sky. View of top of cliff-forming White Rim Sandstone (Permian) and Green River from top of Junction Butte, Canyonlands National Park, Utah. Photography by Jacqueline E. Huntoon, Pennsylvania State University, University Park, Pennsylvania. End_of_Article - Last_Page 647------------

Twenty-nine species of fishes were collected in the middle and upper Colorado River basins in 1967-1973. The native suckers, Catostomus latipinnis and C. discobolus, were the dominant species in the study area. Introduced species outnumbered native species 19 to 10. The introduced Ictalurus punctatus and Notropis lutrensis were abundant throughout most of the upper basin. The abundance of introduced species has increased steadily since 1900 as has the introductions of new species. Four endemic species, Ptychocheilus lucius, Gila elegans, Gila cypha, and Xyrauchen texanus, are considered endangered. These rare forms reproduce in the lower Yampa River, Desolation Canyon of middle Green River, and the lower Green River in Canyon-lands National Park. The major reasons for the decline of native fishes are considered to be alterations of habitat by high dams and introductions of exotic species.

Movement patterns, behavior, and habitat use of razorback sucker stocking into the Green River at Canyonlands National Park, Utah

Many kinds of mammals reach their distributional limits in Utah. This is especially true of rodents restricted to montane or desert habitats. The diverse topography has been instrumental in developing many isolated or semi-isolated populations that have subsequently evolved into recognizable kinds. The central mountain ranges, beginning in northern and northeastern Utah, extend in a southern and southwestern direction. These mountains separate the deserts of the Lake Bonneville Basin from those of the Colorado Drainages of southern, southeastern and eastern Utah. Correspondingly, the desert areas in which antelope ground squirrels occur are also separated. In eastern and southeastern Utah, the Green and Colorado rivers, and their tributaries, with their deeply entrenched canyons, are also barriers that restrict gene flow between populations of antelope ground squirrels. In attempting to re-evaluate the effects of river systems and mountain barriers on the evolution and subspeciation of antelope ground squirrels in Utah, two populations...

Many soils in southeastern Utah are protected from surface disturbance by biological soil crusts that stabilize soils and reduce erosion by wind and water. When these crusts are disturbed by land use, soils become susceptible to erosion. In this study, we compare a never-grazed grassland in Canyonlands National Park with two historically grazed sites with similar geologic, geomorphic, and geochemical characteristics that were grazed from the late 1800s until 1974. We show that, despite almost 30 years without livestock grazing, surface soils in the historically grazed sites have 38–43% less silt, as well as 14– 51% less total elemental soil Mg, Na, P, and Mn content relative to soils never exposed to livestock disturbances. Using magnetic measurement of soil magnetite content (a proxy for the stabilization of far-traveled eolian dust) we suggest that the differences in Mg, Na, P, and Mn are related to wind erosion of soil fine particles after the historical disturbance by livestock grazing. Historical grazing may also lead to changes in soil organic matter content including declines of 60–70% in surface soil C and N relative to the never-grazed sites. Collectively, the differences in soil C and N content and the evidence for substantial rock-derived nutrient loss to wind erosion implies that livestock grazing could have long-lasting effects on the soil fertility of native grasslands in this part of southeastern Utah. This study suggests that nutrient loss due to wind erosion of soils should be a consideration for management decisions related to the long-term sustainability of grazing operations in arid environments.

Hopi pottery sherds dating to the PIV period have been documented at sites throughout southeastern Utah, but an unusual cache of Hopi Pueblo IV whole vessels, gourds, shredded bark, and corn cobs, found in an alcove in a remote location in Canyonlands National Park, raises new questions about long-distance interactions in the protohistoric period. The pottery appears to date sometime between AD 1450 and 1629, and to come from the Hopi Mesas. Carbon dating of samples from the gourds and bark returned dates that conformed well with the relative dates of the pottery. One of the pots contained salt; inductively coupled plasma mass spectrometry analysis of a salt sample from the pot was compared to other natural and cultural salt samples from the region. The source of the cache salt is yet to be determined. Possible explanations are explored, including (1) persistent occupation of the region by Pueblo populations into the Pueblo IV period, (2) intermittent use of the area by PIV people for the purposes of hunting, gathering, visiting shrines, and/or salt gathering, and (3) interaction and trade between Numic speakers and the Hopi during the PIV period, with Numic people leaving behind Hopi pottery sherds and vessels.