Rocky Mountain Front Range Research Articles

Aerosol fluorescence, airborne hexosaminidase, and quantitative genomics distinguish reductions in airborne fungal loads following major school renovations.

Fluorescent aerosol cytometry (FAC) was compared to concurrent recovery of airborne β-N-acetylhexosaminidase (NAHA) and quantitative polymerase chain reaction (qPCR) for the respective ability of these methods to detect significant changes in airborne fungal loads in response to building renovations. Composite, site-randomized indoor aerosol samples for airborne fungi measurements were acquired from more than 70 occupied classrooms in 26 different public schools in the Colorado Rocky Mountain Front Range region of the United States. As judged by ANOVA and Pearson's correlation test, statistically significant associations were observed between real-time FAC and airborne NAHA levels, which detected significant reductions in airborne fungal loads immediately following building rehabilitations. With lower confidence, a statistically significant association was also resolved between fluorescing aerosols, NAHA levels, and the recovery of fungal 18S rRNA gene copies by qPCR from simultaneous, collocated aerosol samples. Quantitative differences encountered between the recovery of common genomic markers for airborne fungi and that of optical and biochemical methods are attributed to the variance in 18S rRNA target gene copies that different fungal species can host.

Spatiotemporal Characteristics and Large-Scale Environments of Mesoscale Convective Systems East of the Rocky Mountains

ABSTRACT The spatiotemporal variability and three-dimensional structures of mesoscale convective systems (MCSs) east of the U.S. Rocky Mountains and their large-scale environments are characterized across all seasons using 13 years of high-resolution radar and satellite observations. Long-lived and intense MCSs account for over 50% of warm season precipitation in the Great Plains and over 40% of cold season precipitation in the southeast. The Great Plains has the strongest MCS seasonal cycle peaking in May–June, whereas in the U.S. southeast MCSs occur year-round. Distinctly different large-scale environments across the seasons have significant impacts on the structure of MCSs. Spring and fall MCSs commonly initiate under strong baroclinic forcing and favorable thermodynamic environments. MCS genesis frequently occurs in the Great Plains near sunset, although convection is not always surface based. Spring MCSs feature both large and deep convection, with a large stratiform rain area and high volume of rainfall. In contrast, summer MCSs often initiate under weak baroclinic forcing, featuring a high pressure ridge with weak low-level convergence acting on the warm, humid air associated with the low-level jet. MCS genesis concentrates east of the Rocky Mountain Front Range and near the southeast coast in the afternoon. The strongest MCS diurnal cycle amplitude extends from the foothills of the Rocky Mountains to the Great Plains. Summer MCSs have the largest and deepest convective features, the smallest stratiform rain area, and the lowest rainfall volume. Last, winter MCSs are characterized by the strongest baroclinic forcing and the largest MCS precipitation features over the southeast. Implications of the findings for climate modeling are discussed.

Constraining the Large‐Scale Analysis of a Regional Rapid‐Update‐Cycle System for Short‐Term Convective Precipitation Forecasting

AbstractThis study examines the impact of a large‐scale constraint (LSC) on the large‐scale analysis and precipitation forecast of convective weather systems in a regional rapid‐update‐cycle system. The LSC is imposed by assimilating Global Forecast System forecast fields as bogus observations with a scale selection scheme. The scale selection is achieved by skipping data points of Global Forecast System forecast fields in the horizontal and vertical directions. It is shown that the LSC is able to modify the large‐scale component of the analysis fields while leaving the small‐scale component mostly intact compared with a control experiment without the constraint. The effects of the LSC on precipitation forecast are verified and analyzed using nine convective cases in the Rocky Mountain Front Range and its east plains. The results show that the LSC is effective in improving the precipitation forecast of different cases. However, the cases with weak large‐scale forcing show greater improvements than those with strong large‐scale forcing. Further analyses on the dynamic and thermodynamic variables indicate that the use of the LSC is able to construct a favorable environment for the initiation and development of convection in the case of weak large‐scale forcing, which leads to significant improvement of convective precipitation forecasting when radar observations are assimilated.

Evaluation of Groundwater Levels in the Arapahoe Aquifer Using Spatiotemporal Regression Kriging

AbstractGroundwater monitoring is fundamental to understanding system dynamics, trends in storage, and the long‐term sustainability of an aquifer. Water‐level data are the key source of information used to understand the response. However, groundwater‐level data are often irregularly sampled, leading to temporal gaps in the record, and are not adequately distributed spatially across an aquifer. This presents challenges when spatially interpolating potentiometric surfaces and creating groundwater maps due to data availability. We present a spatiotemporal kriging methodology to improve spatial and temporal confidence in groundwater‐level predictions at unsampled locations. The space–time data set consists of a trend and residual component modeled with a linear regression and utilize a sum‐metric model to represent spatiotemporal covariances. The Arapahoe aquifer is used as a case study to demonstrate the benefits of spatiotemporal kriging over spatial kriging across a sparsely gauged and irregularly sampled aquifer. The Arapahoe aquifer is a major source of water for many residents along the Rocky Mountain Front Range in Colorado. The results show superior performance of spatiotemporal kriging to predict groundwater levels over the traditional spatial kriging. Spatiotemporal kriging represents realistic temporal and spatial changes in water levels and avoids some of the problems inherent to spatial kriging. This study demonstrates the power of spatiotemporal kriging to help inform system dynamics in irregularly sampled aquifers.

Rapid temporal changes in root colonization by arbuscular mycorrhizal fungi and fine root endophytes, not dark septate endophytes, track plant activity and environment in an alpine ecosystem.

Fungal root endophytes play an important role in plant nutrition, helping plants acquire nutrients in exchange for photosynthates. We sought to characterize the progression of root colonization by arbuscular mycorrhizal fungi (AMF), dark septate endophytes (DSE), and fine root endophytes (FRE) over an alpine growing season, and to understand the role of the host plant and environment in driving colonization levels. We sampled four forbs on a regular schedule from June 26th-September 11th from a moist meadow (3535m a.s.l) on Niwot Ridge, Rocky Mountain Front Range, CO, USA. We quantified the degree of root colonization by storage structures, exchange structures, and hyphae of all three groups of fungi. AMF and FRE percent colonization fluctuated significantly over time, while DSE did not. All AMF structures changed over time, and the degree of change in vesicles differed by plant species. FRE hyphae, AMF arbuscules and AMF vesicles peaked late in the season as plants produced seeds. AMF hyphae levels started high, decreased, and then increased within 20days, highlighting the dynamic nature of plant-fungal interactions. Overall, our results show that AMF and FRE, not DSE, root colonization rapidly changes over the course of a growing season and these changes are driven by plant phenology and seasonal changes in the environment.

From oil field to geothermal reservoir: assessment for geothermal utilization of two regionally extensive Devonian carbonate aquifers in Alberta, Canada

Abstract. The Canadian province of Alberta has one of the highest per capita CO2-equivalent emissions in Canada, predominantly due to the industrial burning of coal for the generation of electricity and mining operations in the oil sands deposits. Alberta's geothermal potential could reduce CO2 emissions by substituting at least some fossil fuels with geothermal energy.The Upper Devonian carbonate aquifer systems within the Alberta Basin are promising target formations for geothermal energy. To assess their geothermal reservoir potential, detailed knowledge of the thermophysical and petrophysical rock properties is needed. An analogue study was conducted on two regionally extensive Devonian carbonate aquifers, the Southesk-Cairn Carbonate Complex and the Rimbey-Meadowbrook Reef Trend, to furnish a preliminary assessment of the potential for geothermal utilization. Samples taken from outcrops were used as analogues to equivalent formations in the reservoir and correlated with core samples of the reservoir. Analogue studies enable the determination and correlation of facies-related rock properties to identify sedimentary, diagenetic, and structural variations, allowing for more reliable reservoir property prediction.Rock samples were taken from several outcrops of Upper Devonian carbonates in the Rocky Mountain Front Ranges and from four drill cores from the stratigraphically equivalent Leduc Formation and three drill cores of the slightly younger Nisku Formation in the subsurface of the Alberta Basin. The samples were analyzed for several thermophysical and petrophysical properties, i.e., thermal conductivity, thermal diffusivity, and heat capacity, as well as density, porosity, and permeability. Furthermore, open-file petrophysical core data retrieved from the AccuMap database were used for correlation.The results from both carbonate complexes indicate good reservoir conditions regarding geothermal utilization with an average reservoir porosity of about 8 %, average reservoir permeability between 10−12 and 10−15 m2, and relatively high thermal conductivities ranging from 3 to 5 W m−1 K−1. The most promising target reservoirs for hydrothermal utilisation are the completely dolomitized reef sections. The measured rock properties of the Leduc Formation in the subsurface show no significant differences between the Rimbey-Meadowbrook Reef Trend and the Southesk-Cairn Carbonate Complex. Differences between the dolomitized reef sections of the examined Leduc and Nisku Formation are also minor to insignificant, whereas the deeper basinal facies of the Nisku Formation differs significantly.In contrast, the outcrop analogue samples have lower porosity and permeability, likely caused by low-grade metamorphism and deformation during the Laramide orogeny that formed the Rocky Mountains. As such, the outcrop analogues are not valid proxies for the buried reservoirs in the Alberta Basin.Taken together, all available data suggest that dolomitization enhanced the geothermal properties, but depositional patterns and other diagenetic events, e.g., fracturing, also played an important role.

GEOLOGICAL NOTE

Abstract The term “Sukunka Formation” is proposed for a 113 to 169 metre thick mixed siliciclastic and carbonate unit lying between the Middle Devonian Stone and Dunedin Formations in the Rocky Mountain Front Ranges of northeastern British Columbia. The unit is best developed near the headwaters of the Sukunka River, where it outcrops along a series of closely spaced imbricate thrusts. In the type area, it can be divided into three (informal) members: lower, middle and upper. The lower member overlies the Stone Formation unconformably and consists of inter-bedded orthoquartzite, dolostone and sandy dolostone. It is overlain by the middle member that consists predominantly of brick red weathering siltstones interbedded with minor amounts of dolostone. These ‘red beds’ are readily recognizable in the field and can be used elsewhere in the area to identify thrust imbricates. The upper member consists of a series of thick to massive bedded, well cross-bedded and resistant weathering clean quartzose sandstones which gradationally overlie the middle member. The top of the formation is also disconformable. It is transgressed and overlain by the basal calcareous shales and limes of the Dd-1 member of the Dunedin Formation. However, lag deposits from the Sukunka Formation occur within the basal calcareous shales and limes of the Dd-1 member. This condition is thought to reflect progressive transgression of higher stratigraphic levels of the Sukunka Formation to the east by the rising waters that led to accumulation of the Dunedin Formation. Diagnostic fossils have not been recognized in the Sukunka Formation. Presently, it is dated as early Middle Devonian based solely on stratigraphic position. In the subsurface, in the same stratigraphic position between the Stone and Dunedin formations, unnamed argillaceous, sandy and silty carbonates have also been identified. These, further to the east, may be equivalent to the unnamed detrital unit of the Chinchaga Formation.

Swell-Dominated Carbonates On A Mississippian Ramp In the Canadian Rocky Mountain Front Ranges

Abstract The Livingstone Formation and the middle Opal Member of the Mount Head Formation of western Canada are Mississippian carbonate deposits, tens to hundreds of meters thick, that are interpreted to have accumulated in a mid-ramp, wave-dominated, sub-thermocline environment, at water depths up to 100 m or more. The rocks are predominantly pelmatozoan grainstones and packstones that contain abundant physical sedimentary structures. The most common sedimentary structures are planar lamination, swaly and hummocky cross-stratification, and normally graded event beds that are interpreted as having been formed by oscillatory (wave) currents or oscillatory-dominated combined flows. The abundant oscillatory currents are interpreted to have been generated by swell waves and to a lesser extent by local storms. High-angle, planar-tabular cross bedding is also present in rare, discrete beds produced by unidirectional offshore-directed currents. The unidirectional currents that produced the dunes are interpreted to have been generated by coastal set-up that produced downwelling storm currents during the rare storms that occurred along the Mississippian coastline. It is hypothesized that local storms were not common due to the west-coast location and the tropical latitude of the study area. Instead it is postulated that swell waves, approaching from the broad Panthalassa Ocean to the west, were responsible for most sediment remobilization and deposition across the mid and outer ramp. Swell waves are believed to have resuspended sediment to greater depths than short-period, less-organized storm waves. These Mississippian deposits suggest that in situ grain production on the ramp, without need for the offshore transport of sediment from the shoreface, resulted in two major differences from siliciclastic wave-dominated settings: 1) swaly cross-stratification was not restricted to environments shallower than hummocky cross-stratification on the upper shoreface, because sand-size sediment was generated across a large portion of the ramp; and 2) aggradation by means other than sediment supply from shallower water caused preservation of deep-water swell-dominated deposits.

Newly described Gomphonema and Gomphosphenia from Rocky Mountain Front Range streams, Colorado, USA, with additional discussion of rarely reported taxa

A new species of Gomphonema, G. capsulare, and a new species of Gomphosphenia, G. praegnans, are described from samples collected from two streams in the Front Range of the Colorado Rocky Mountains. Gomphonema capsulare is small with linear valve margins and its stigma lies very close to the centre of the valve. Gomphosphenia praegnans is very small with widely lanceolate-clavate valves readily distinguishing it from other described Gomphosphenia species. In addition to the two new species, two other species in the same genera were also identified from these samples, Gomphonema exilissimum (Grunow) Lange-Bertalot & E. Reichardt in Lange-Bertalot & Metzeltin and Gomphosphenia americana Kociolek & E.W. Thomas in Kociolek et al. This paper provides the first images and morphological description of a population of G. exilissimum from North America. Gomphonema exilissimum is morphologically similar to G. parvulum (Kützing) Kützing but has a different ecological niche. Documentation of G. americana in this paper expands the currently known range of this species. In addition, this paper documents the presence of internal hymenate occlusions in the areolae in both G. americana and G. praegnans, a feature previously unknown in this genus.

Comparison of the Impacts of Momentum Control Variables on High-Resolution Variational Data Assimilation and Precipitation Forecasting

Abstract The momentum variables of streamfunction and velocity potential are used as control variables in a number of operational variational data assimilation systems. However, in this study it is shown that, for limited-area high-resolution data assimilation, the momentum control variables ψ and χ (ψχ) pose potential difficulties in background error modeling and, hence, may result in degraded analysis and forecast when compared with the direct use of x and y components of wind (UV). In this study, the characteristics of the modeled background error statistics, derived from an ensemble generated from Weather Research and Forecasting (WRF) Model real-time forecasts of two summer months, are first compared between the two control variable options. Assimilation and forecast experiments are then conducted with both options for seven convective events in a domain that encompasses the Rocky Mountain Front Range using the three-dimensional variational data assimilation (3DVar) system of the WRF Model. The impacts of the two control variable options are compared in terms of their skills in short-term qualitative precipitation forecasts. Further analysis is performed for one case to examine the impacts when radar observations are included in the 3DVar assimilation. The main findings are as follows: 1) the background error modeling used in WRF 3DVar with the control variables ψχ increases the length scale and decreases the variance for u and υ, which causes negative impact on the analysis of the velocity field and on precipitation prediction; 2) the UV-based 3DVar allows closer fits to radar wind observations; and 3) the use of UV control variables improves the 0–12-h precipitation prediction.

Incorporating biotic factors in species distribution modeling: are interactions with soil microbes important?

It is increasingly recognized that species distributions are driven by both abiotic factors and biotic interactions. Despite much recent work incorporating competition, predation, and mutualism into species distribution models (SDMs), the focus has been confined to aboveground macroscopic interactions. Biotic interactions between plants and soil microbial communities are understudied as potentially important drivers of plant distributions. Some soil bacteria promote plant growth by cycling nutrients, while others are pathogenic; thus they have a high potential for influencing plant occurrence. We investigated the influence of soil bacterial clades on the distributions of bryophytes and 12 vascular plant species in a high elevation talus‐field ecosystem in the Rocky Mountain Front Range, Colorado, USA. We used an information‐theoretic criterion (AICc) modeling approach to compare SDMs with the following different sets of predictors: abiotic variables, abiotic variables and other plant abundances, abiotic variables and soil bacteria clade relative abundances, and a full model with abiotic factors, plant abundances, and bacteria relative abundances. We predicted that bacteria would influence plant distributions both positively and negatively, and that these interactions would improve prediction of plant species distributions. We found that inclusion of either plant or bacteria biotic predictors generally improved the fit, deviance explained, and predictive power of the SDMs, and for the majority of the species, adding information on both other plants and bacteria yielded the best model. Interactions between the modeled species and biotic predictors were both positive and negative, suggesting the presence of competition, parasitism, and facilitation. While our results indicate that plant–plant co‐occurrences are a stronger driver of plant distributions than plant–bacteria co‐occurrences, they also show that bacteria can explain parts of plant distributions that remain unexplained by abiotic and plant predictors. Our results provide further support for including biotic factors in SDMs, and suggest that belowground factors be considered as well.

Algal community ecology of two Rocky Mountain Front Range streams

This study examined the composition and ecology of benthic algal communities within two streams of the Colorado Rocky Mountains. Algal community samples as well as physical and chemical habitat parameters were collected from Boulder Creek and St. Vrain Creek between July and August, 2013. Sampling began in the high elevation montane headwaters for each stream and continued downstream to the low elevation plains locations with a total of 41 samples collected. Algal communities from each stream were dominated by diatoms. Algal cell densities and species diversity were highly variable within each stream, and there was no difference in overall cell density or species diversity between the streams. Despite the close proximity of Boulder Creek and St. Vrain Creek, differences in algal community composition were found between the two streams. Differences in the algal communities between the two streams were found to be a result of higher conductivity, temperature, and pH and increased levels of total nitrogen in Boulder Creek compared to St. Vrain Creek.

The Great Colorado Flood of September 2013

Abstract During the second week of September 2013, a seasonally uncharacteristic weather pattern stalled over the Rocky Mountain Front Range region of northern Colorado bringing with it copious amounts of moisture from the Gulf of Mexico, Caribbean Sea, and the tropical eastern Pacific Ocean. This feed of moisture was funneled toward the east-facing mountain slopes through a series of mesoscale circulation features, resulting in several days of unusually widespread heavy rainfall over steep mountainous terrain. Catastrophic flooding ensued within several Front Range river systems that washed away highways, destroyed towns, isolated communities, necessitated days of airborne evacuations, and resulted in eight fatalities. The impacts from heavy rainfall and flooding were felt over a broad region of northern Colorado leading to 18 counties being designated as federal disaster areas and resulting in damages exceeding $2 billion (U.S. dollars). This study explores the meteorological and hydrological ingredients that led to this extreme event. After providing a basic timeline of events, synoptic and mesoscale circulation features of the event are discussed. Particular focus is placed on documenting how circulation features, embedded within the larger synoptic flow, served to funnel moist inflow into the mountain front driving several days of sustained orographic precipitation. Operational and research networks of polarimetric radar and surface instrumentation were used to evaluate the cloud structures and dominant hydrometeor characteristics. The performance of several quantitative precipitation estimates, quantitative precipitation forecasts, and hydrological forecast products are also analyzed with the intention of identifying what monitoring and prediction tools worked and where further improvements are needed.

Elevation-Dependent Temperature Trends in the Rocky Mountain Front Range: Changes over a 56- and 20-Year Record

Determining the magnitude of climate change patterns across elevational gradients is essential for an improved understanding of broader climate change patterns and for predicting hydrologic and ecosystem changes. We present temperature trends from five long-term weather stations along a 2077-meter elevational transect in the Rocky Mountain Front Range of Colorado, USA. These trends were measured over two time periods: a full 56-year record (1953–2008) and a shorter 20-year (1989–2008) record representing a period of widely reported accelerating change. The rate of change of biological indicators, season length and accumulated growing-degree days, were also measured over the 56 and 20-year records. Finally, we compared how well interpolated Parameter-elevation Regression on Independent Slopes Model (PRISM) datasets match the quality controlled and weather data from each station. Our results show that warming signals were strongest at mid-elevations over both temporal scales. Over the 56-year record, most sites show warming occurring largely through increases in maximum temperatures, while the 20-year record documents warming associated with increases in maximum temperatures at lower elevations and increases in minimum temperatures at higher elevations. Recent decades have also shown a shift from warming during springtime to warming in July and November. Warming along the gradient has contributed to increases in growing-degree days, although to differing degrees, over both temporal scales. However, the length of the growing season has remained unchanged. Finally, the actual and the PRISM interpolated yearly rates rarely showed strong correlations and suggest different warming and cooling trends at most sites. Interpretation of climate trends and their seasonal biases in the Rocky Mountain Front Range are dependent on both elevation and the temporal scale of analysis. Given mismatches between interpolated data and the directly measured station data, we caution against an over-reliance on interpolation methods for documenting local patterns of climatic change.

Characterization of rhizosphere fungi from selenium hyperaccumulator and nonhyperaccumulator plants along the eastern Rocky Mountain Front Range

Selenium-hyperaccumulator plants can store over 1% (dry mass) Se in their tissues, despite the toxicity of this element at high concentrations across eukaryotes. These levels of Se can have widespread effects on the plant's ecological partners, including herbivores and pathogens. Still other partners seem to have coevolved Se tolerance. This is the first known study addressing the rhizosphere mycoflora of Se hyperaccumulators and aims to evaluate the rhizospheric fungal diversity and Se tolerance to further the knowledge of how these organisms interact with their host plants and survive in these extreme habitats. Rhizosphere fungi were isolated from Se-hyperaccumulator and nonaccumulator plant species collected from five sites in Colorado and Wyoming; four seleniferous sites and one nonseleniferous site. 259 isolates were identified to genus or species and evaluated for Se tolerance. Among the 24 represented genera, 11 comprised 86% of the isolates. The majority of isolates from the seleniferous sites were unaffected by 10 mg·L(-1) Se, irrespective of host plant (hyperaccumulator vs. nonaccumulator), while rhizosphere fungi from a control, nonseleniferous site were highly sensitive to Se at 10 mg·L(-1) and as a group were significantly less (α = 0.05) tolerant than the isolates from the seleniferous sites. Even though Se is a commonly used antifungal agent, these results suggest that rhizosphere fungi from seleniferous habitats have widespread Se tolerance, likely an adaptive advantage in their Se-rich habitat.

Characteristics of a paleosol and its implication for the Critical Zone development, Rocky Mountain Front Range of Colorado, USA

Activity and stability phases as well as geomorphic processes within the Critical Zone are well known. Erosion and deposition of sediments represent activity; soils represent geomorphic stability phases. Data are presented from a 4 m deep sediment section that was dated by luminescence techniques. Upslope erosion and resulting sedimentation started in the late Pleistocene around 18 ka until 12 ka. Conditions at the study site then changed, which led to the formation of a well-developed soil. Radiocarbon dating of the organic matter yielded ages between 8552 and 8995 cal. BP. From roughly 6.2 to 5.4 ka another activity phase accompanied by according sediment deposition buried the soil and a new soil, a Cambisol, was formed at the surface. The buried soil is a strongly developed Luvisol. The black colors in the upper part of the buried soil are not the result of pedogenic accumulation of normal organic matter within an A-horizon. Nuclear magnetic resonance spectroscopy clearly documents the high amount of aromatic components (charcoal), which is responsible for the dark color. This indicates severe burning events at the site and the smaller charcoal dust (black carbon) was transported to deeper parts of the profile during the process of clay translocation.

Homelands: How Women Made the West (review)

Reviewed by: Homelands: How Women Made the West Sue Armitage Homelands: How Women Made the West. By Virginia Scharff and Carolyn Brucken. Berkeley: University of California Press, 2010. 170 pages, $24.95. It seems that western women's history has been trapped by domesticity. Thanks to the images of Ma Ingalls and all those other fictional mothers, we have come to imagine western women always in the house, away from the "real" action—and much of women's history has seemed to confirm this image. The first widely used concept in western women's history, the Cult of True Womanhood, awkwardly transported the domestic ideal for middle-class urban and eastern women to the West. The influential work of Annette Kolodny extended the term, but only to the garden fence. Glenda Riley used domesticity so widely as the common denominator for western women that race, class, and region dwindled in significance. Later uses of domesticity, as in Brigitte Georgi-Findlay's The Frontiers of Women's Writing (1996) were again imported, this time from international feminist scholars trying to crack the masculine bias in the study of British imperialism. As this quick survey suggests, it is high time for western women to break the restraints, a task that Virginia Scharff and Carolyn Brucken undertake with gusto, literally redefining the word home to mean the entire process of occupying, claiming, and defending land. In one interpretation, this is simply [End Page 439] Patricia Limerick's contest for property and profit dressed up in gender terms. But in another sense, the redefinition moves women to the center of western history, for Scharff and Brucken are certainly right to say that, seen through this lens, the story of the West, is "a story of women creating and claiming home places" (1). Their insight feels absolutely true; the problem is what to do with it. Scharff and Brucken suggest a solution as radical as their redefinition: scrapping the framework of linear national history and envisaging a history of varied, often unconnected homeplaces stretching far back to before European conquest and extending forward into the present. To illustrate what this might mean, they offer three essays on the history of women's creation of homeplaces in three very different environments: northern New Mexico, Denver and the Rocky Mountain Front Range, and Puget Sound in the Pacific Northwest. The three histories are briskly undertaken, with a clear focus on women of many ethnicities adapting to new environments and shaping them—active, creative women, not the passive or trivial stereotypes of "old" western history. Each of the three sections has its own thematic emphasis: in northern New Mexico, the convergence of cultures; in Colorado, the interaction of women and transportation; in Puget Sound, women and water. This is an intriguing thesis, but Homelands does not explore it as fully as it deserves. This beautifully produced book is the companion volume to a woman-focused exhibit at the Autry National Museum in Los Angeles, so of necessity it is short and popular, and the exhibit, one assumes, can only offer a sketch of the larger argument. It left me interested, but asking, "What about culture? politics? economics?" and also, of course, "What does it mean to make the West, or for that matter, anywhere else?" Sue Armitage Washington State University, Pullman Copyright © 2011 The Western Literature Association

A lake sediment-based proxy of floods in the Rocky Mountain Front Ranges, Canada

We analyzed lake sediment deposits and local hydrometric records to assess the potential for developing a high-resolution record of sediment delivery from the Rock Lake catchment, situated in the non-glacierized Front Ranges of the Rocky Mountains, Canada. Rhythmic couplets of silt–clay characterized the clastic sediments recovered from the deep central basin of the lake. Contemporary sediment yield to Rock Lake (10.7 ± 1.8 Mg km−2 year−1) is comparable to other studied Canadian Cordillera lakes that have sedimentary lithologies and absence of glacier cover, but distinct rhythmic deposition is relatively unique to this basin. Spatial patterns of deposition within the lake were assessed by correlating rhythmites between multiple sediment cores and by sub-bottom, acoustic profiling. Bracketed dates for a spatially continuous sequence of eight thick rhythmites were established by correlating laminations between core samples collected more than 30 years apart. We identified a consistent pattern between the rhythmite and hydrometric data series between 1975 and 2006 and determined that specific flooding events caused by summer rainstorms are associated with each of the eight thick rhythmites. We observed a good relationship between rhythmite thickness and total flood volume that exceeded a threshold discharge. Acoustic profiling showed that the lake could be a good candidate for longer-term proxy development. We discuss how some of the methods used in this study could benefit ongoing paleoenvironmental assessments based on lacustrine rhythmite series.

Response of the Phytoplankton Community in an Alpine Lake to Drought Conditions: Colorado Rocky Mountain Front Range, U.S.A

Lakes may serve as sentinels for the impacts of changing climate in alpine areas. In the Rocky Mountain region, 2002 was a year with extremely low snowpack. We examined the summer phytoplankton community in Green Lake 4 for a 6-year period that included the summer of 2002. The phytoplankton community variation was examined in the context of the changes in physical and chemical properties of Green Lake 4. The physical changes associated with the 2002 drought included warmer surface water temperatures and greater hydraulic residence times; whereas the chemical changes included higher concentrations of acid neutralizing capacity (ANC) and major ions. During the summer of 2002 the phytoplankton community was dominated by Synedra sp. and Ankyra sp.; two previously rare species. The growth of Synedra sp. was sufficient to cause a decrease in silica concentrations, which has not been observed in other summers in the water quality monitoring record. The results of a redundancy analysis (RDA) indicated that concentrations of major ions and ANC were aligned with Synedra sp. and Ankyra sp. during the 2002 drought year. Following the 2002 drought year, Chrysococcus sp. and Chlorococcum sp., which became abundant, were aligned with nitrate in the RDA. These results indicate that the response of the phytoplankton community to the extreme drought was most strongly correlated with water quality changes that occurred, rather than temperature and hydraulic residence time. The dominant species in the post-drought phytoplankton community were found to be associated with nitrate, which is brought to the watershed by atmospheric deposition and may represent an anthropogenic driver of phytoplankton community composition.

Stability analysis of a horizontal coalbed methane well in the Rocky Mountain Front Ranges of southeast British Columbia, Canada

This study describes a wellbore stability analysis undertaken for a horizontal coalbed methane well in the Mist Mountain Formation, SE British Columbia, Canada. Three triaxial compression tests, with ultrasonic velocities, were conducted on 38-mm-diameter core plugs taken from a large, fresh block of Seam 7. Due to the small size of the tested samples, the laboratory-derived strength values were reduced to reflect the in-situ stress conditions considered relevant for a 156-mm-diameter horizontal well. The vertical stress gradient was calculated by integrating a bulk density log from an offset well. Horizontal maximum and minimum stresses were estimated from regional stress data, whereas formation pressure was estimated on the basis of a local hydrological study. The 2D elastoplastic STABView™ numerical modeling code was used to forecast horizontal wellbore stability. The sensitivity of the predicted yielded zone size was examined for varying linear and non-linear rock strength criteria, horizontal in-situ stresses, bottom-hole pressures, formation pressure, drilling depth, and wall-coating efficiency. Stability analysis was performed at bottom-hole pressures ranging from overbalanced to underbalanced in order to simulate the conditions expected during drilling and production. The effects of weak bedding planes and varying well trajectories were also investigated. When drilling at 650 m depth under underbalanced to slightly overbalanced conditions, a high probability of getting the drill pipe stuck was predicted. STABView™ showed that, if the 38-mm-diameter core plug strengths were used directly for forecasting purposes, the predicted yielded zone would be almost 20% overgauge when drilling at balanced conditions. When peak cohesion of coal was reduced by 50% to reflect the conditions expected along weak intervals of a horizontal wellbore, the predicted enlarged borehole was almost 85% overgauge under the same drilling conditions. The most unstable trajectory has N–S azimuth, which is perpendicular to the maximum horizontal stress in the study area. STABView™ indicates that a production liner should be inserted immediately following the drilling of the horizontal well in this structurally complex geologic setting since pressure drawdown and reservoir pressure depletion would undoubtedly lead to enlarged yielded zones and collapse of the wellbore over time.