Canyonlands Research Articles

Responses of Desert Bighorn Sheep to Increased Human Recreation

Human recreation has been implicated in the decline of several populations of desert bighorn sheep (Ovis is canadensis nelsoni). Managers are concerned about the impact of increased recreation on desert bighorn sheep in Canyonlands National Park (NP), Utah, USA, where visitation increased 325% from 1979 to 1994. We compared behavioral responses of sheep to recreational activity between a low visitor use area and a high visitor use area during 1993 and 1994 by observing behavioral responses, distances moved, and duration of responses to vehicles, mountain bikers, and humans on foot. Hikers caused the most severe responses in desert bighorn sheep (animals fled in 61% of encounters), followed by vehicles (17% fled) and mountain bikers (6% fled), apparently because hikers were more likely to be in unpredictable locations and often directly approached sheep. We observed considerable individual heterogeneity in responses of bighorn sheep to the greater human use: some animals lived close to the road corridor and were apparently habituated to the human activities, but other animals avoided the road corridor. In the high-use area, we observed 3 radiocollared sheep that lived closer to the road than expected and found evidence of fewer responses to vehicles by females in spring, less response time of all sheep to vehicles in spring, and fewer responses to mountain bikers compared to the low-use area. Overall, there was an avoidance of the road corridor by most other bighorn sheep in the high-use area where all animals, on average, were found 39% farther from roads (490 ± 19 m vs. 354 ± 36 m) than in the low-use area. This avoidance of the road corridor by some animals represented 15% less use of potential suitable habitat in the high-use area over the low-use area. Increased sensitivity to hikers in the high-use area was suggested by a greater responsiveness by males in autumn and greater distance fled by females in spring. Responses of bighorn sheep were greater when human activity approached at the same elevation, when sheep were moving or standing, when female interactions occurred in spring and summer and male interactions occurred in autumn, and when sheep were farther from escape terrain. We recommend managers confine hikers to designated trails during spring lambing and the autumn rut in desert bighorn sheep habitat.

MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF FOUR NOSTOC SPECIES ISOLATED FROM DESERT SOILS

Kubecková, K.1, Johansen, J. R.1, Li X.2 & Vincent, J.1 1Department of Biology, John Carroll University, University Heights, OH 44118 USA; 2Botany Department, Miami University, Oxford OH 45056 USAFour strains of Nostoc were isolated and characterized with regards to morphology and life cycle. Three strains were isolated from microbiotic soil crusts in the Mojave Desert of Southern California, and one strain was isolated from the lichen Collema tenax from crusts in Canyonlands National Park. All four strains were found to be morphologically distinct, with differences in: macrocolony appearance, microcolony shape and size, density of trichomes within the microcolony, and hormogonia production. The most commonly reported species from desert soils is Nostoc commune Vaucher. However, our strains all differ from that taxon in the size and shape of akinetes and heterocysts. Collema tenax is reported to have Nostoc commune as its phycobiont, but our observations on the phycobiont indicate that it is very distinct from that species and other Nostoc we have observed in desert soils. We subsequently sequenced a partial sequence of the 16SrRNA gene and the associated internal transcribed spacer (ITS) between the 16SrRNA and 23SrRNA genes for all four strains. Evidence of three multiple rRNA operons each was recovered for two strains, based upon configuration and sequence differences in the ITS regions. ITS with the following configurations were observed: no tRNA genes, tRNAIle and tRNAAla genes, and the beginning portion of tRNAIle immediately followed by the end portion of tRNAAla. Although our strains appear distinct from the descriptions of species in Geitler (1932) and Starmach (1966), further molecular characterization of species in this genus is probably warranted before they are assigned to existing or new species.

America's Cellular Telephone Obsession: New Geographies of Personal Communication

Every one of us has dreams in progress-yearnings whose fulfillment may lie in that voice at the other end of the phone's ring. -Paul Levinson, The Soft Edge: A Natural History and Future of the Information Revolution Not long ago I stood at a scenic overlook in Canyonlands National Park near Moab, Utah watching a man on his cell phone describe the scene below. Seconds after completing the call he was dialing again, repeating his account of sparse vegetation, deeply incised canyons and vivid red and brown colors. From snarled urban highways and suburban shopping malls to airport waiting areas and golf courses, the cellular phone has become an icon for America's love affair with mobility and connectivity. Between 1995 and 2001, nearly 82 million people became cell phone users, increasing wireless subscriptions in the U.S. to over 116 million (CTIA). Heated competition for subscribers has led to marketing campaigns claiming clearer reception, less expensive airtime charges, or extended features such as call forwarding, email, paging, or Internet access. Even children's toys are emulating the wireless craze with make-believe phones included in McDonalds Happy Meals and TV commercials promoting tiny cellular phones that come with Cabbage Patch dolls. When first introduced in the early 1980s, the high cost of cellular service meant that the majority of wireless phones were used for business purposes. However, within the last ten years declining costs have contributed to cell phone ownership that transcends income, occupation, and age. With the number of worldwide subscribers approaching one billion, the cell phone is among the world's most successful consumer products. The revolution in cell use has influenced the lifestyles and communication patterns of Americans in several ways as demonstrated by the growing number of cell users who have elected to go without wired phone service in their homes. Most significantly, mobility and access have brought new possibilities for personal communication. As suggested by Wooldridge the wireless has effectively dispersed personal communication, blurring boundaries between private and public spaces and changing patterns of business and personal communication. The explosion in cellular use has also impacted the cultural landscape with tens of thousands of cell towers and antennas planned or in use to serve geographically expanding wireless networks. Despite rapid acceptance of cellular technology among most Americans, the social and cultural impacts of wireless have attracted little scholarly attention (Katz and Aspden). A Brief History of Mobile Communication The promise of a mobile device for personal communication has captured the imagination of Americans for years. Comic book character Dick Tracy used a tiny wristwatch phone to communicate while Don Adams on TV's Get Smart popularized the shoe phone. More closely resembling today's flip-open cellular phones were hand-held communicators used on the TV series Star Trek. Although short-lived, the Citizens Band (CB) radio craze of the late 1960s and early 1970s demonstrated the public's enthusiasm for inexpensive mobile communication. CB became the wireless equivalent of the rural party line with 23 and later 40 channels enabling voice communication from moving automobiles or fixed locations. However, the limited range of CBs along with their unregulated use and inability to offer privacy made them poor substitutes for telephones. Although not wireless, an early car telephone can be credited to Lars Magnus Ericsson, founder of Ericsson Telephone (Farley). Touring the Swedish countryside in his horseless carriage in 1910, Ericsson and his wife would stop near overhead poles and extend a long stick with a hook over each wire. With a few cranks on the phone's dynamo handle Ericsson could alert a nearby exchange operator to assist in initiating a call. …

Population Growth, Fecundity, and Survivorship in Recovering Populations of Bighorn Sheep

AbstractThe single greatest obstacle to the restoration of large, healthy, populations of bighorn sheep (Ovis canadensis) in the western United States is epizootic outbreaks of bronchopneumonia that may kill 20–100% of the animals in populations. Although the species is capable of rapid initial growth rates following restoration into new habitat (λ = 1.23–1.30 have been observed), these rates of increase are typical only a few years following the release of a population, and then most populations either decline to extirpation or remnant status (<30 animals) or remain at <100 individuals. We studied the fecundity and survivorship of three increasing, and three declining and suspected diseased, populations of bighorn sheep (the latter were subjected to outbreaks of bronchopneumonia) located in or near several large national parks in the western United States from 1991 to 1996. Titers verified both population categories were exposed to the bacteria Pasteurella haemolytica serotypes 3; 4; and 3, 4, 10; Moraxella sp., and parainfluenza‐3 and bluetongue (BT) viruses. Pregnancy rates of adult ewes were not different in increasing or decreasing populations (pooled rate = 0.93; p = 0.57), but pregnancy rates of yearlings were lower (0.00 for decreasing vs. 0.33 for increasing populations), initial production of lambs and annual recruitment of lambs was lower (0.14, decreasing vs. 0.66, p < 0.05). Adult survival was lower during the first year of an epizootic, 0.62, in one population, but recovered to 0.85 by the second and subsequent years. Survival of adult rams was variable in diseased populations; in two populations rams appeared to be disproportionately impacted, but in a third population rams survived better during the epizootic. In all the increasing park (unhunted) populations, adult ram survival (0.94 ± 0.01) was higher than adult ewe survival (0.89 ± 0.02) (p = 0.10), in contrast to published information from hunted populations where ram survival was lower. Removal of about 20% of one population for restorations severely impacted one declining population. Removals of 12–20% appeared to be excessive and were not readily compensated for in the Canyonlands National Park desert bighorn population. Disease was a significant limiting factor to restoration of bighorn sheep in the study areas; six of 11 total recovering populations we monitored closely were negatively influenced by apparent disease at some time during our observations.

Seismic reflection study of Upheaval Dome, Canyonlands National Park, Utah

The origin of Upheaval Dome, in Canyonlands National Park of southeastern Utah, has been a topic of controversy among geologists and planetary scientists. The structure has long been thought to have been created by salt diapirism from the underlying Paradox Formation. Recent studies have suggested that impact could have formed the dome. To test the various hypotheses, we acquired, processed, and interpreted seismic reflection data within and adjacent to the structure. Both conventionally stacked and prestack‐migrated images show <100 m relief in the Paradox Formation, contrary to salt diapirism hypotheses. Further, we have identified features within the images typical of impact structures, such as listric normal faults having displacements toward the center of the dome. Deformation occurs in two depth ranges, with the faulting that created the central uplift appearing only above the Hermosa Formation, in the upper 800 m of the structure. The images also suggest limited fracturing of the Hermosa and salt flow in the Paradox Formation, perhaps due to gravitational relaxation of the crater form. Our image of a nearly flat top of the Paradox salt strongly favors an impact origin for Upheaval Dome.

Benthic invertebrates of a large, sandy river system: The Green and Colorado Rivers of Canyonlands National Park, Utah

From July, 1994 to November, 1995 we sampled the benthos of the Green and Colorado Rivers of Canyonlands National Park, Utah at the request of the United States National Park Service. This study was conceived with a goal of establishing baseline densities of invertebrates in these rivers in preparation for a long-term biomonitoring program. Four remote sites were sampled on each river during each of seven trips. At each site, benthic organisms retained by a 63-μm mesh were collected from three habitats: sand runs - regions of strong downstream flow and a coarse, shifting substrate; sand beaches - depositional regions with slower currents and finer substrates; and backwaters - cut-off channels with no downstream flow, typically with the finest substrate and no current. Densities of meiofauna and macroinvertebrates were estimated. Three taxa dominated the community: Nematoda, Rotifera, and Oligochaeta. Ostracods and cladocera were common under certain conditions. We identified 28 genera of chironomids and 29 species from 11 families of rotifers. Analysis of variance indicated that total invertebrate densities were different in the three sampled habitats and in the two rivers at different discharge levels. Eighteen separate analyses of variance were employed to test whether the densities of 18 taxa differed significantly between the two rivers, among three habitats, and at different times and discharge levels. Nine taxa exhibited significant differences in density for interactions involving the rivers. Densities of 13 taxa were significantly different between the three habitats or in some interaction involving these habitats. The effects of discharge and/or habitat age were significant for 11 of the taxa. However, these two variables were often significant in the same analyses and in high-order interactions, suggesting that complex dynamics influence the distribution of these organisms.

A petrographical and geochemical study of quartzose nodules, country rocks, and dike rocks from the Upheaval Dome structure, Utah

Abstract— Upheaval Dome, in Canyonlands National Park, Utah, USA, is a unique structure on the Colorado Plateau. It has earlier been interpreted as an impact structure or as a pinched‐off salt diapir. Some subrounded quartzose fragments were found in a ring depression near the eastern margin of the structure and, based on vesicularity and apparent flow structure, the fragments were interpreted by early researchers as “impactites.” Our petrographic studies show no indication of a high‐temperature history and are in agreement with a slow, low‐temperature formation of the quartz nodules. Composi***ionally, the lag deposit samples are almost pure SiO2. They show no chemical similarity to any of the possible target rocks (e.g., Navajo Sandstone), from which they should have formed by melting if they were impactites. Instead, the samples have relatively high contents of elements that indicate fluid interaction (e.g., hydrothermal growth), such as As, Sb, Ba, and U, and show positive Ce anomalies. Thus, we interpret the “lag deposit samples” as normal low‐temperature (hydrothermally‐grown?) quartz that show no indication of being impact‐derived. In addition, a petrographic and geochemical analysis of a series of dike samples yielded no evidence for shock metamorphism or a meteoritic component.

Processes of faulting in jointed rocks of Canyonlands National Park, Utah

Detailed studies of 11 segmented normal faults from five grabens in the Needles District of Canyonlands National Park, Utah, demonstrate key processes in the growth, linkage, and evolution of grabens. Field observations and stereophotogrammetry reveal a ubiquitous asymmetry in cross-sectional geometry, based on distinct map patterns of graben-bounding faults, rollover anticlines with attendant joint dilation, footwall uplift with joint closure, and spoon-shaped graben floors. Master and antithetic faults across Devils Lane and several other grabens are defined quantitatively by the displacement distributions along the faults. Two-dimensional shape parameters that characterize the displacement profiles indicate that inelastic processes such as changes in fault frictional strength influence strain accumulation along the faults. The degree of graben asymmetry increases systematically with distance from the Colorado River; greater symmetry is associated with locally greater age and/or strain of grabens nearer the river. Scatter in plots of maximum displacement vs. fault length was attributed previously to linkage of fault segments alone but is here shown to correlate additionally with distance from the Colorado River and, therefore, to spatial strain gradients within the graben array. Extensional strain across the fault array, accumulating at rates of perhaps 1.5 to 2 cm/yr or 10−14 to 10−13 s−1, is accommodated at depth by salt flow and formation of reactive salt diapirs beneath the grabens and was probably initiated when the Colorado River had cut sufficiently deep into the section for active salt diapirism to commence.

Evaluation of hybrid power system alternatives: a case study

Pursuant to executive and statutory policies, the National Park Service (NPS) has been evaluating the use of photovoltaic (PV) hybrid power systems for many of its remote, off-grid areas. This paper reports the results of a detailed technical and economic evaluation for one such area: the Needles District of Canyonlands National Park. The study evaluates the present power system and five alternative power generation configurations, four of which utilize PV. Projections are provided for the generator run-time and fuel use associated with each configuration as well as all initial and future costs. Included in the study are specific recommendations for energy efficiency improvements at the site. Results show that the generation system presently in use, two full-time diesel generators, has the lowest conventional20-year life cycle cost (LCC) of the six systems evaluated. However, when emissions costs are included (per NPS guidelines), several of the PV hybrid alternatives attain a lower LCC than the diesel-only system. General discussion of the effects of initial versus future costs for PV hybrids as they compare with engine generator systems is presented. Copyright © 1999 John Wiley & Sons, Ltd.

Structure and evolution of Upheaval Dome: A pinched-off salt diapir

Upheaval Dome (Canyonlands National Park, Utah) is an enigmatic structure previously attributed to underlying salt doming, cryptovolcanic explosion, fluid escape, or meteoritic impact. We propose that an overhanging diapir of partly extrusive salt was pinched off from its stem and subsequently eroded. Many features support this inference, especially synsedimentary structures that indicate Jurassic growth of the dome over at least 20 m.y. Conversely, evidence favoring other hypotheses seems sparse and equivocal. In the rim syncline, strata were thinned by circumferentially striking, low-angle extensional faults verging both inward (toward the center of the dome) and outward. Near the dome's core, radial shortening produced constrictional bulk strain, forming an inward-verging thrust duplex and tight to isoclinal, circumferentially trending folds. Farther inward, circumferential shortening predominated: Radially trending growth folds and imbricate thrusts pass inward into steep clastic dikes in the dome's core. We infer that abortive salt glaciers spread from a passive salt stock during Late Triassic and Early Jurassic time. During Middle Jurassic time, the allochthonous salt spread into a pancake-shaped glacier inferred to be 3 km in diameter. Diapiric pinch-off may have involved inward gravitational collapse of the country rocks, which intensely constricted the center of the dome. Sediments in the axial shear zone beneath the glacier steepened to near vertical. The central uplift is inferred to be the toe of the convergent gravity spreading system.

Lateral displacement variation and lateral tip geometry of normal faults in the Canyonlands National Park, Utah

The along-strike displacement variation of 20 well-exposed normal faults from the Canyonlands, Utah, is described and analysed. The displacement profiles of these faults are highly variable, and most irregularities can be related to fault segmentation. Many of the profiles are highly asymmetric, and this can be related to mechanical interaction in some cases. Linear displacement tapers are observed towards all the lateral tips, but the percentage of trace length over which this linear taper occurs is highly variable. Three distinct lateral tip geometries are recognised, referred to informally as types A, B and C. Type A tips have a simple Mode III displacement geometry, Type B tips are characterised by a zone of extensional ‘fissures’ surrounding the fault tip, and Type C tips are characterised by the development of a monocline beyond the tip. Lateral displacement variation towards tips was analysed by measuring displacement gradients from systematic positions along the fault trace. Lateral displacement gradients measured for 39 tips exhibit a wide range of values (0.016–0.25). Fourteen of these lateral tips are regarded as ‘active’ since they exhibit signs of recent surface rupturing. These active tips have a similar range of lateral displacement gradients (0.019–0.25) to the overall population. Lateral displacement gradients were correlated with fault parameters such as length, length/maximum displacement (for faults and segments), and proximity to adjacent faults. No positive correlations were found. We suggest that the large range of lateral displacement gradients is mainly due to interactions between neighbouring faults. Additional complexities are likely to have resulted from strength heterogeneities related to jointing, from local variations in remote loading stresses and the frictional properties of the fault surfaces, and from processes related to segment linkage.

Fine particulate chemical composition and light extinction at Canyonlands National Park using organic particulate material concentrations obtained with a multisystem, multichannel diffusion denuder sampler

The concentration of fine particulate carbonaceous material has been measured over a 1‐year period at the Interagency Monitoring of Protected Visual Environments (IMPROVE) Canyonlands National Park, Utah sampling site using a Brigham Young University organic sampling system (BOSS) multisystem, multichannel diffusion denuder sampler. Samples were collected on the IMPROVE schedule of a 24‐hour sample every Wednesday and Saturday. The concentrations of particulate C, determined using only a quartz filter pack sampling system, were low by an average of 39%, as a result of the loss of semi‐volatile organic compounds from the particles collected on quartz filters during sampling. The loss was higher during the summer than during the winter sampling periods. The BOSS and IMPROVE quartz filter carbon measurements were in agreement except for a few samples collected during the summer. The fine particulate carbonaceous material concentrations determined using the BOSS have been combined with concentrations of particulate elemental C (soot), sulfate, nitrate, crustal material, and fine and coarse particulate mass from the IMPROVE sampling system, as well as relative humidity, light absorption, and transmissometer measurements of light extinction from IMPROVE. Extinction budgets have been calculated using multilinear regression analyses of the data set. Literature data were used to estimate the change in the mass extinction coefficients for the measured species as a function of relative humidity. The results show carbonaceous material to be the principal contributor to light extinction due to particles during the study period, with the major contributor to light extinction being light‐absorbing carbonaceous material. However, the periods of maximum light extinction are associated with high humidity and the associated increased scattering of light due to particulate sulfate during the winter. The effect of particulate organic compounds on light extinction is greatest in the summer and smallest in the winter.

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

Spherical aluminosilicate (SAS) particles, total fluoride and particulate trace elements are potential endemic tracers for determining and quantifying the presence of coal-fired power plant and other sulfur oxide source emissions at far downwind distances. These endemic tracers, and sulfate and SO 2 were collected at Canyonlands National Park, at seven ambient sampling sites located in air mass transport paths to Canyonlands and from the stacks of coal-fired power plants in central Utah during January-March of 1990 for use in source apportionment analyses. These data have been combined with results obtained in concurrent studies by the National Park Service (EPIC study) and Salt River Project to provide a complete data set for the characterization of the regional and point sources that can influence air quality in the Canyonlands area. This paper gives details on the study design and on the chemical composition of fine particulate matter in the study area. While concentrations of SO x (SO 2(g) plus particulate sulfate) were in good agreement among the various studies, accurate concentrations for sulfate and SO 2 were only obtained using a diffusion denuder sampling system because of the absorption of SO 2(g) by particles in all filter pack sampling systems. Concentrations of FT Total (HF(g) plus particulate fluoride), and particulate Se, As, and Pb determined by multiple techniques were generally in good agreement. Sulfate (assumed present as ammonium sulfate) and nitrate (assumed present as ammonium nitrate) accounted for an average of 19 and 4%, respectively, of the fine particulate mass collected at Canyonlands and 8 and 2% of the fine particulate mass at Green River, Utah. Data were available at the Edge of the Cedars, Utah, sampling site to estimate the complete chemical composition of the fine particles. The average concentration of fine particles at Edge of the Cedars was 15 μg m −3. Sulfate (as the ammonium salt) averaged 15% of the fine particulate mass, comparable to Canyonlands. Nonsulfate inorganic compounds averaged 58% of the mass. The majority of these inorganic species are background desert particles. The remainder of the mass, 27%, is presumably water, and organic and elemental carbon.

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

During January-March of 1990 a study was conducted to determine the sources of sulfur oxide emissions present in the Canyonlands area in Utah. Samples were collected at the Island-in-the-Sky visitors center in Canyonlands National Park and at several sites circling the park to characterize the chemical composition of air masses influencing the receptor sites from various geographical regions. The results of the sampling program and the identified chemical fingerprints of the sources that can impact the Canyonlands receptor site have been given in the first two papers in a series of three papers. In this paper are presented the results of chemical mass balance source apportionment of the SO x , present at Canyonlands, Green River, Bullfrog Marina and Edge of the Cedars, Utah, using the chemical composition and source fingerprint data given in the preceding papers. The results indicate that the presence of sulfur oxides at the Canyonlands area is a regional problem not dominated by a single source. The contributions to SO x , at Canyonlands during the 21 days included in the source apportionment analyses included sources to the southwest (37%),south and southeast (20%), north and northeast (19%), and northwest (23%). At the Edge of the Cedars State Park to the southeast of Canyonlands, sources from the southeast contributed 51 % of the observed SO x . At Bullfrog Marina in the Lake Powell National Recreation Area, southwest of Canyonlands, sources to the southwest were responsible for 81 % of the SO x present. At Green River, to the north of Canyonlands, the contribution of sources to the north and northeast were reduced (10%) because the major transport path of sources from these directions was the movement of emission from northwestern Colorado down the Colorado River drainage and south of Green River. The apportionment of sulfate at Canyonlands has been estimated from a combination of the chemical mass balance SO x source apportionment results, the measured concentrations of S02 and particulate sulfate, and meteorological data. This analysis indicates that, while the main source of SO x at Canyonlands is from emissions to the southwest, the main source of sulfate is from SO x emissions originating from the southeast of Canyonlands.

Decomposition of AVIRIS spectra: extraction of surface-reflectance, atmospheric, and instrumental components

Presents techniques that use only information contained within a raw, high-spectral-resolution, hyperspectral Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) scene to estimate and remove additive components (atmospheric scattering and instrument dark current). These techniques allow normalization of multiplicative components (instrument gain, topography, atmospheric transmission) and enhancement, extraction, and identification of relative-reflectance information related to surface composition and mineralogy. The authors' derivation of additive components from raw AVIRIS data is based on an adaptation of Crippen's "regression intersection method (RIM)." As does RIM, the authors use pairs of surface units that are spectrally homogeneous, spatially extensive, and located in rugged terrain. However, their technique utilizes the long-wavelength spectral data of AVIRIS to derive and remove atmospheric scattering components for each unit. AVIRIS data from the Kelso Dunes and Granite Mountain areas of southern California served as spectrally contrasting, topographically modulated surfaces for illustration of this technique. For a given site and wavelength pair, subtraction of the wavelength-dependent additive component from individual bands will remove topographic shading in both sites in band-to-band ratio images. Normalization of all spectra in the scene to the average scene spectrum results in cancellation of multiplicative components and produces a relative-reflectance scene. Absorption features due to mineral absorptions that depart from the average spectrum can be identified in the relative-reflectance AVIRIS product. The validity of these techniques is demonstrated by comparisons between relative-reflectance AVIRIS spectra derived from application of this technique and those derived by using the standard calibration techniques of JPL. Calibrated spectra were extracted from an AVIRIS scene of the Upheaval Dome area of Canyonlands National Park, UT. Results show that surface-reflectance information can be extracted and interpreted in terms of surface mineralogy after application of these techniques to AVIRIS data.

Roberts Rift, Canyonlands, Utah, A Natural Hydraulic Fracture Caused by Comet or Asteroid Impact

AbstractThe impact that created Upheaval crater in Canyonlands National Park, Utah, is invoked here as the source for energy that simultaneously caused Roberts rift. However, no temporal linkage has been proven between the impact and rifting events.Roberts rift lies between 22 and 32 km northeast of the Upheaval impact crater on a subradial trend. The fissure contains clasts that were carried as much as 1,000 m upward from Paleozoic sources into the Mesozoic section.A plausible model for both the rifting and clast movement involves incremental loading of overpressured fluid compartments in the Pennsylvanian Paradox section and attendant hydraulic fracturing of the overlying confining strata during the impact event. The clasts were proppants entrained in upward moving fluids that originated from overpressured aquifers in the Pennsylvanian section or materials eroded from the fissure walls.Alteration halos and mineralization along the fissure reveal that there was upward leakage of reducing fluids from the overpressured zones following opening of the fissure. The fissure infillings became cemented with time, thus reducing fissure permeabilities to negligible.

Relay-ramp forms and normal-fault linkages, Canyonlands National Park, Utah

Fieldwork within a series of mesoscale grabens in southeast Utah has revealed a particularly well-exposed system of interlinked extensional faults. A series of down-faulted grabens are developed within a 460-m-thick brittle layer of upper Paleozoic sandstone and shale, which overlies a ductile layer with a high gypsum content. All the major grabens consist of two or more overlapping elements, which are composed of fault segments. These segments may be hard-linked (fault surfaces are joined) or soft-linked (fault surfaces are isolated, but linked by ductile strain of the rock volume between them) in map view. Relay structures are defined as zones connecting the footwalls and hanging walls of overlapping fault segments representing soft linkage of fault segments. In the Canyonlands grabens, the transfer of displacement between soft-linked fault segments is characterized by well-de-fined, dipping relay ramps, commonly rotated and extended to accommodate the ductile strain between the overlapping fault segments. Relay ramps develop as ephemeral structures, eventually becoming breached by hard linkage of the fault segments. Breakdown of ramps by breaching is part of the process of fault growth by segment linkage. Within the Canyonlands graben system, four orders of segmentation are present. This may be a consequence of different scales of mechanical heterogeneity, but evidence from the Canyonlands grabens and elsewhere points to a fundamental process of discontinuous fault growth by segment linkage.

A multiple-system, multi-channel diffusion denuder sampler for the determination of fine-particulate organic material in the atmosphere

Measurement of the loss of semi-volatile organic compounds from particles collected with a filter is carried out by comparing the amounts collected by comparable filter pack and diffusion denuder samplers. The sorbents used to collect organic compounds in the denuder and sorbent filters must have the same efficiency for collection of all gas-phase organic compounds present. Interpretation of the data requires that the efficiency of collection of gas-phase compounds by the denuder be known. In theory this can be accomplished by determination of the deposition pattern of all organic compounds collected in the denuder, but in practice this is very difficult if the organic material consists of a wide variety of compounds. An alternative approach is to determine the breakthrough of organic compounds in a sampler with a particle-collection filter preceding the denuder and sorbent filter. In such a sampler only gas-phase organic material enters the denuder. We have developed both a multi-channel parallel plate diffusion denuder sampler and a comparable sampler in which the denuder is preceded by a filter. Samples can be collected with the multisystem sampler at a flow rate of 35 sLpm. The denuder surfaces and the sorbent filters are made from sheets of an activated charcoal-impregnated filter paper. Collection of semi-volatile compounds by the samplers has been characterized and the systems have been field tested. The samplers are now being used for the routine collection and determination of semi-volatile organic compounds in particles at Canyonlands National Park in southeastern Utah. Available data from this field program show significant losses of particulate organic compounds on a quartz filter due to volatilization during sampling.

Biogeography of Invertebrates and Plants in Hanging Gardens of the Colroado Plateau

The field work portion of our research on the biogeography of invertebrates and vascular plants has been completed. The geomorphological, bumble bee pollinator and plant community models developed during the first two field seasons worked well when applied to new sites in Dinosaur National Monument (DINO), Canyonlands National Park CANY), Arches National Park (ARCH), and Natural Bridges National Monument (NABR). Our research objectives for the 1993 field season were to: (1) complete the survey of plant and insect communities of hanging gardens in DINO, ARCH, CANY, and NABR; and (2) determine the geographic distribution of endemic species identified and the level of endemism within and among parks; and (3) complete the Halls Creek area survey for hanging gardens in Capitol Reef National Park (CARE).

The WHITEX Study and the Role of the Scientific Community: A Critique

In Winter 1987, the Denver office of the National Park Service carried out the Winter Haze Intensive Tracer Experiment (WHITEX) whose original purpose was only to investigate the feasibility of using an inert tracer to determine the contribution of a point source, the Navajo Generating Station (NGS), to the haze in Canyonlands National Park. Deuterated methane was used to trace NGS's emissions. The WHITEX study was then used as a basis of regulatory action. Unfortunately, the WHITEX study report, and papers, suffer from serious errors in implementation, analysis and interpretation.