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At least 289 records · Page 16Linked to original sources
USGS2009

Preliminary geologic map of the Cook Inlet region, Alaska-Including parts of the Talkeetna, Talkeetna Mountains, Tyonek, Anchorage, Lake Clark, Kenai, Seward, Iliamna, Seldovia, Mount Katmai, and Afognak 1:250,000-scale quadrangles

The growth in the use of Geographic Information Systems (GIS) has highlighted the need for digital geologic maps that have been attributed with information about age and lithology. Such maps can be conveniently used to generate derivative maps for manifold special purposes such as mineral-resource assessment, metallogenic studies, tectonic studies, and environmental research. This report is part of a series of integrated geologic map databases that cover the entire United States. Three national-scale geologic maps that portray most or all of the United States already exist; for the conterminous U.S., King and Beikman (1974a,b) compiled a map at a scale of 1:2,500,000, Beikman (1980) compiled a map for Alaska at 1:2,500,000 scale, and for the entire U.S., Reed and others (2005a,b) compiled a map at a scale of 1:5,000,000. A digital version of the King and Beikman map was published by Schruben and others (1994). Reed and Bush (2004) produced a digital version of the Reed and others (2005a) map for the conterminous U.S. The present series of maps is intended to provide the next step in increased detail. State geologic maps that range in scale from 1:100,000 to 1:1,000,000 are available for most of the country, and digital versions of these state maps are the basis of this product. The digital geologic maps presented here are in a standardized format as ARC/INFO export files and as ArcView shape files. The files named __geol contain geologic polygons and line (contact) attributes; files named __fold contain fold axes; files named __lin contain lineaments; and files named __dike contain dikes as lines. Data tables that relate the map units to detailed lithologic and age information accompany these GIS files. The map is delivered as a set 1:250,000-scale quadrangle files. To the best of our ability, these quadrangle files are edge-matched with respect to geology. When the maps are merged, the combined attribute tables can be used directly with the merged maps to make derivative maps.

Alaska↗
USGS2014

Historical and contemporary imagery to assess ecosystem change on the Arctic coastal plain of northern Alaska

The Arctic Coastal Plain of northern Alaska is a complex landscape of lakes, streams, and wetlands scattered across low-relief tundra that is underlain by permafrost. This region of the Arctic has experienced a warming trend over the past three decades leading to thawing of on-shore permafrost and the disappearance of sea ice at unprecedented rates. The U.S. Geological Survey’s (USGS) Changing Arctic Ecosystems (CAE) research initiative was developed to investigate and forecast these rapid changes in the physical environment of the Arctic, and the associated changes to wildlife populations, in order to inform key management decisions by the U.S. Department of the Interior and other agencies. Forecasting future wildlife responses to changes in the Arctic can benefit greatly from historical records that inform what changes have already occurred. Several Arctic wildlife and plant species have already responded to climatic and physical changes to the Arctic Coastal Plain of northern Alaska. Thus, we located historical aerial imagery to improve our understanding of recent habitat changes and the associated response to such changes by wildlife populations. In this report, we describe and make available a set of 61 georectified aerial images of the Arctic Coastal Plain (taken from 1948 to 2010) that were obtained by the USGS to inform research objectives of the USGS CAE Initiative. Here, we describe the origins, metadata, and public availability of these images that were obtained within four main study areas on the Arctic Coastal Plain: Teshekpuk Lake Special Area, Chipp River, the Colville River Delta, and locations along the Dalton Highway Corridor between the Brooks Range and Deadhorse. We also provide general descriptions of observable changes to the geomorphology of landscapes that are apparent by comparing historical and contemporary images. These landscape changes include altered river corridors, lake drying, coastal erosion, and new vegetation communities. All original and georectified images and metadata are available through the USGS Alaska Science Center Portal (search under ‘Project Name’ using title of this report) or by contacting ascweb@usgs.gov .

Alaska↗
USGS2009

Mine spoil prairies expand critical habitat for endangered and threatened amphibian and reptile species

Coal extraction has been occurring in the Midwestern United States for over a century. Despite the pre-mining history of the landscape as woodlands, spent surface coalfields are often reclaimed to grasslands. We assessed amphibian and reptile species on a large tract of coal spoil prairie and found 13 species of amphibians (nine frog and four salamander species) and 19 species of reptiles (one lizard, five turtle, and 13 snake species). Two state-endangered and three state species of special concern were documented. The amphibian diversity at our study site was comparable to the diversity found at a large restored prairie situated 175 km north, within the historic prairie peninsula.

Diversity↗
USGS2007

Responses of hydrochemical inorganic ions in the rainfall-runoff processes of the experimental catchments and its significance for tracing

Aimed at the rainfall-runoff tracing using inorganic ions, the experimental study is conducted in the Chuzhou Hydrology Laboratory with special designed experimental catchments, lysimeters, etc. The various runoff components including the surface runoff, interflow from the unsaturated zone and the groundwater flow from saturated zone were monitored hydrometrically. Hydrochemical inorganic ions including Na+, K+, Ca2+, Mg2+, Cl-, SO42-, HCO3- + CO32-, NO3-, F-, NH4-, PO42-, SiO2 and, pH, EC, 18O were measured within a one month period for all processes of rainfall, various runoff components and groundwater within the catchment from 17 boreholes distributed in the Hydrohill Catchment, few soil water samples were also included. The results show that: (a) all the runoff components are distinctly identifiable from both the relationships of Ca2+ versus Cl-/SO42-, EC versus Na+/(Na+ + Ca2+) and, from most inorganic ions individually; (b) the variation of inorganic ions in surface runoff is the biggest than that in other flow components; (c) most ions has its lowermost concentration in rainfall process but it increases as the generation depths of runoff components increased; (d) quantitatively, ion processes of rainfall and groundwater flow display as two end members of that of other runoff components; and (e) the 18O processes of rainfall and runoff components show some correlation with that of inorganic ions. The results also show that the rainfall input is not always the main source of inorganic ions of various runoff outputs due to the process of infiltration and dissolution resulted from the pre-event processes. The amount and sources of Cl- of runoff components with various generation mechanisms challenge the current method of groundwater recharge estimation using Cl-.

Shuikexue Jinzhan/Advances in Water Science↗
USGS2021

Habitat selection in a southern Lake Sturgeon population: Implications of temporal, spatial, and ontogenetic variation for restoration

Successful species reintroduction requires restoration of receiving habitats to support growth, survival, and reproduction that reverse the initial causes of decline. Little is known about whether present habitat conditions can support all life stages of reintroduced southern Lake Sturgeon populations that were possibly extirpated by the mid-1900s due to overharvest and habitat degradation. Therefore, we conducted a telemetry study to assess annual adult and subadult and overwinter age-0 Lake Sturgeon habitat selection and suitability in two Missouri River U.S. tributaries near the southern edge of the species range. Spring habitat selection models were unable to define spawning habitat criteria, but criteria from other studies suggest that substrate and depths for spawning are suitable in both rivers. In the summer and winter, adult and subadult Lake Sturgeon exhibited strong selection for pools greater than 8 m deep, which comprised less than 5% of our study streams. Habitat selection in the fall and winter by age-0 Lake Sturgeon differed from adults with age-0s selecting shallower habitats both rivers and swifter current velocities in the Gasconade River. General habitat patterns persisted for both life stages in each river regardless of habitat availability, suggesting specialized habitat requirements in southern Lake Sturgeon that differ from previously studied populations further north. These results may be used to direct sampling for validation of reproduction and restoration of not only spawning habitats, but age-0 and summer and winter refugia that may be potential restoration bottlenecks for southern Lake Sturgeon populations.

Missouri↗
USGS1903

Chemical analyses of igneous rocks published from 1884 to 1900, with a critical discussion of the character and use of analyses

In the first two or three decades of the last century, when the study of rocks as such was being differentiated from that of minerals and of rock terranes that is, when the science of petrogaphy was in its infancy little attention was paid to their chemical features. It is true that a number had been analyzed, but these were for the most part rocks that were of such a character as to lead the investigator of those early days to consider them as minerals, as was the case with the first described Ihcrzolite and wehrlite. In contradistinction to the individually well-defined minerals, rocks were regarded as merely aggregates of minerals, in presumably fortuitous combinations, and lacking that definiteness or constancy of composition in one mass or in different masses which would justify their chemical study as a whole. As, however, they became more and more the subjects of special research, beginning with the earliest investigations of Cordiera, a knowledge of their chemical composition assumed gradually increasing interest. The great importance of this side of the study of rocks was first clearly recognized by Abich, who pointed out, as early as 1841, the, necessity of a knowledge of their chemical composition for the solution of such problems as their origin, mode of formation, and connection with the interior of the earth, as well as the value of a comparison of their analyses as a proper basis for their classification and nomenclature. To him, therefore, is due the credit, of introducing the chemical composition of rocks as a basis for their classification; though the good influence of this suggestion for their right understanding was largely nullified by the coincident use of the feldspars alone as one of the main factors of classification, an idea which has had a deplorably retarding influence on the development of systematic petrography for many years, and which, even at the present day, holds many systematists firmly in its grasp.

Professional Paper↗
USGS2010

Why do some, but not all, tropical birds migrate? A comparative study of diet breadth and fruit preference

Annual migrations of birds profoundly influence terrestrial communities. However, few empirical studies examine why birds migrate, in part due to the difficulty of testing causal hypotheses in long-distance migration systems. Short-distance altitudinal migrations provide relatively tractable systems in which to test explanations for migration. Many past studies explain tropical altitudinal migration as a response to spatial and temporal variation in fruit availability. Yet this hypothesis fails to explain why some coexisting, closely-related frugivorous birds remain resident year-round. We take a mechanistic approach by proposing and evaluating two hypotheses (one based on competitive exclusion and the other based on differences in dietary specialization) to explain why some, but not all, tropical frugivores migrate. We tested predictions of these hypotheses by comparing diets, fruit preferences, and the relationships between diet and preference in closely-related pairs of migrant and resident species. Fecal samples and experimental choice trials revealed that sympatric migrants and residents differed in both their diets and fruit preferences. Migrants consumed a greater diversity of fruits and fewer arthropods than did their resident counterparts. Migrants also tended to have slightly stronger fruit preferences than residents. Most critically, diets of migrants more closely matched their preferences than did the diets of residents. These results suggest that migrants may be competitively superior foragers for fruit compared to residents (rather than vice versa), implying that current competitive interactions are unlikely to explain variation in migratory behavior among coexisting frugivores. We found some support for the dietary specialization hypothesis, propose refinements to the mechanism underlying this hypothesis, and discuss how dietary specialization might ultimately reflect past interspecific competition. We recommend that future studies quantify variation in nutritional content of tropical fruits, and determine whether frugivory is a consequence or a cause of migratory behaviour.

Evolutionary Ecology↗
USGS1979

Organochlorine and mercury residues in Swainson's hawk eggs from the Pacific Northwest

Many raptorial species in the Pacific Northwest have not been studied from the viewpoint of pollutant contamination. The Swainson's Hawk ( Buteo swainsoni ) is particularly interesting because of its highly migratory characteristic; it apparently winters primarily in Argentina (Brown and Amadon 1968, Houston 1968). White and Cade (1977) and others have suggested Central America and South America as possible sources of pesticide contamination for wintering raptors from North America. The spraying of DDT in the Northwest in 1974 provided the opportunity to study several forest-dwelling raptors (Henny 1977); and in 1976, we made a special effort to collect a series of eggs of Swainson's Hawks from northeastern Oregon (some adjacent to the area sprayed with DDT in 1974) and southeastern Washington. This study was undertaken to determine organochlorine pesticide and other pollutant burdens in the Swainson's Hawk.

Oregon, Washington↗
USGS1998

The Soufriere Hills eruption, Montserrat, British West Indies: Introduction to special section, part 1

The special section on the eruption of Soufriere Hills volcano is a collection of 24 papers that summarises the early scientific work of the Montserrat Volcano Observatory. Part 1 of the special section, published in a previous issue of GRL , provided a sampling of the multidisciplinary investigations undertaken at Montserrat. The papers published in Part 1 included an overview of the eruption, investigations on seismicity, ground deformation studies, and petrology. The papers of this issue comprise Part 2 of the special section. These papers also cover a broad spectrum of topics, including various topics in seismology, petrology, pyroclastic flow models, gas chemistry, hydrothermal systems, and tsunami models. In general, papers in Part 1 may be said to be more observational- or data-orientated, and those of Part 2 more model-orientated, but indeed there is much overlap of descriptive material, data, and modelling within the individual contributions. Considered in total the collection presents a representative summary of the scientific effort carried out in Montserrat through much of 1997.

Geophysical Research Letters↗
USGS1991

Ecology of the island night lizard, Xantusia riversiana, on Santa Barbara Island, California

We studied the population biology and ecology of the island night lizard (Xantusia riversiana) on Santa Barbara Island, California from 1981-1988. We trapped all the major habitats on the island, using pitfall traps and Sherman small mammal traps. In addition to permanently marking individuals by toe-clipping, we used specialized marking techniques on some individuals (fluorescent powder and radioactive tags) to study home range, movement and activity patterns. Island night lizards are exclusively diurnal and exceedingly secretive. Though generally cryptic in coloration, their dorsal coloration is highly variable. They occur most commonly in habitats providing dense vegetative cover (thickets of boxthorn and prickly pear) and in certain types of rock habitat. Night lizards are sedentary and have very small home ranges (x̄=17.2m 2 ). They are slow-growing with some individuals living to at least 12 years old. The most common injuries (tail and scale injuries) apparently result from intraspecific fighting. A wide variety of terrestrial spiders and insects make up the majority of their diet, but they also feed on an unusually large amount of plant material for a small lizard. Because of their diverse diet, low metabolic rate and small, overlapping home ranges, they reach greater densities (>3200 lizards/ha in boxthorn) than previously reported for any other ground-dwelling lizard. Favorable habitat has been reduced because of past farming and grazing, but, given their wide distribution on the island, exceptionally high densities and current protection within a National Park, X. riversiana on Santa Barbara Island are not threatened with extinction, as was previously thought.

Herpetological Monographs↗
USGS2019

Introduction to special issue on gas hydrate in porous media: Linking laboratory and field‐scale phenomena

The proliferation of drilling expeditions focused on characterizing natural gas hydrate as a potential energy resource has spawned widespread interest in gas hydrate reservoir properties and associated porous media phenomena. Between 2017 and 2019, a Special Section of this journal compiled contributed papers elucidating interactions between gas hydrate and sediment based on laboratory, numerical modeling, and field studies. Motivated mostly by field observations in the northern Gulf of Mexico and offshore Japan, several papers focus on the mechanisms for gas hydrate formation and accumulation, particularly with vapor phase gas, not dissolved gas, as the precursor to hydrate. These studies rely on numerical modeling or laboratory experiments using sediment packs or benchtop micromodels. A second focus of the Special Section is the role of fines in inhibiting production of gas from methane hydrate, controlling the distribution of hydrate at a pore scale, and influencing the bulk behavior of seafloor sediments. Other papers fill knowledge gaps related to the physical properties of hydrate-bearing sediments and advance new approaches in coupled thermal-mechanical modeling of these sediments during hydrate dissociation. Finally, one study addresses the long-standing question about the fate of methane hydrate at the molecular level when CO2 is injected into natural reservoirs under hydrate-forming conditions.

Journal of Geophysical Research B: Solid Earth↗
USGS1989

Water-quality data for selected wells and drains in the Oakes study area, south-central North Dakota, December 1986 through September 1987

Operation of the Garrison Diversion Unit in North Dakota will divert water from the Missouri River near Lake Audubon into the upper James River basin (fig. 1). The diverted water will augment flows in the James River sufficiently to permit expanded irrigation and to provide additional water supplies for municipal and industrial use. The proposed Garrison Diversion Unit development and associated expanded irrigation has caused environmental concerns regarding potential mobilization, transport, and concentration of potentially toxic trace elements. In order to address'these concerns, a study of trace elements was made cooperatively by the U.S. Bureau of Reclamation and the U.S. Geological Survey during 1986-88. The traceelement study area consists of approximately 130,000 acres and includes the Turtle Lake, Lincoln Valley, Harvey, New Rockford, LaMoure, and Oakes areas. As part of this study, Severson and others (1988) reported on the baseline geochemistry of soils, with special emphasis on selenium, for an irrigation test area of about 15 square miles near Oakes, N.Dak. This report presents the water-quality data collected during December 1986 through September 1987 from selected wells and drain sites in the Oakes study area.

Open-File Report↗
USGS2018

Position-specific 13C distributions within propane from experiments and natural gas samples

Site-specific carbon isotope measurements of organic compounds potentially recover information that is lost in a conventional, ‘bulk’ isotopic analysis. Such measurements are useful because isotopically fractionating processes may have distinct effects at different molecular sites, and thermodynamically equilibrated populations of molecules tend to concentrate heavy isotopes in one molecular site versus another. Most recent studies of site-specific 13 C in organics use specialized Nuclear Magnetic Resonance (NMR) techniques or complex chemical degradations prior to mass spectrometric measurements. Herein we present the first application of a new mass spectrometric technique that reconstructs the site-specific carbon isotope composition of propane based on measurements of the 13 C/ 12 C ratios of two or more fragment ions that sample different proportions of the terminal and central carbon sites. We apply this method to propane from laboratory experiments and natural gas samples to explore the relationships between site-specific carbon isotope composition, full-molecular δ 13 C, thermal maturity, and variation in organic matter precursors. Our goal is to advance the understanding of the sources and histories of short-chain alkanes within geologic systems. Our findings suggest that propane varies in its site-specific carbon isotope structure, which is correlated with increasing thermal maturity, first increasing in terminal position δ 13 C and then increasing in both center and terminal position δ 13 C. This pattern is observed in both experimental and natural samples, and is plausibly explained by a combination of site-specific, temperature-dependent isotope effects associated with conversion of different precursor molecules (kerogen, bitumen, and/or oil) to propane, differences in site-specific isotopic contents of those precursors, and possibly distillation of reactive components of those precursors with increasing maturity. We hypothesize that the largest changes in site-specific isotopic content of propane occur when bitumen and/or oil replace kerogen as the dominant precursors. If correct, this phenomenon could have significant utility for understanding gas generation in thermogenic petroleum systems.

Geochimica et Cosmochimica Acta↗
USGS2010

Large-scale coastal change in the Columbia River littoral cell: an overview

This overview introduces large-scale coastal change in the Columbia River littoral cell (CRLC). Covering 165 km of the southwest Washington and northwest Oregon coasts, the littoral cell is made up of wide low-sloping dissipative beaches, broad coastal dunes and barrier plains, three large estuaries, and is bounded by rocky headlands. The beaches and inner shelf are composed of fine-grained sand from the Columbia River and are exposed to a high-energy winter wave climate. Throughout the Holocene, the CRLC has undergone large fluctuations in shoreline change trends, responding to a variety of coastal change drivers, including changing rates of sea-level rise, infrequent, yet catastrophic, co-seismic subsidence events, a large regional sediment supply, inter-annual climatic fluctuations (El Niño cycles), seasonally varying wave climate, and numerous anthropogenic influences. Human influences on the CRLC include construction of over 200 dams in the Columbia River drainage basin, dredging of navigation channels removing sand to upland sites and offshore deep-water sites, and construction of large inlet jetties at the entrances to the Columbia River and Grays Harbor. The construction of these massive entrance jetties at the end of the 19th century has been the dominant driver of coastal change through most of the littoral cell over the last hundred years. Presently, some beaches in the littoral cell are eroding in response to nearshore sediment deficits resulting from a) ebb-jets of the confined entrances pushing the previously large, shallow ebb-tidal deltas offshore into deeper water, and b) waves dispersing the nearshore delta flanks initially onshore and then alongshore away from the jetties. This overview describes 1) the motivation for developing a system-wide understanding of sediment dynamics in the littoral cell at multiple time and space scales, 2) the formation and approach of the Southwest Washington Coastal Erosion Study, and 3) an introduction to the papers in this special issue.

Washington;Oregon↗
USGS2016

Introduction to the special issue on the 25 April 2015 Mw 7.8 Gorkha(Nepal) earthquake

On April 25, 2015, a moment magnitude (M w ) 7.8 earthquake struck central Nepal, breaking a section of the broader Himalayan Front that had been largely quiescent in moderate-to-large earthquakes for much of the modern seismological era. Ground shaking associated with the event resulted in a broad distribution of triggered avalanches and landslides. The ensuing aftershock sequence was punctuated by a Mw 7.3 event 17 days after the mainshock. The combined effects of these earthquakes and secondary hazards have led to the Gorkha earthquake becoming the worst natural disaster in Nepal since the 1934 Nepal-Bihar earthquake, causing close to 9000 deaths and severely injuring over 21,000 people ( OCHA, 2015 ). Despite the devastating effects of this earthquake, the convergent margin that hosted it is thought to be capable of much larger ruptures—perhaps as large as Mw 9 ( Feldl and Bilham, 2006 ). The 2015 Gorkha rupture lies just to the west of the 1934 M 8.0–8.4 event ( Sapkota et al., 2013; Bollinger et al., 2014 ). Unlike the 1934 event, which has been documented in paleoseismic trenches along the Himalayan Front (e.g., Sapkota et al., 2013 ), and other large ruptures along the arc (e.g., Lavé et al., 2005; Kumar et al., 2006 ), the 2015 event did not rupture to the surface (e.g., Galetzka et al., 2015 ). As a result, some researchers have suggested that the Gorkha earthquake was not as large, or as damaging, as might have been expected based on our (albeit limited) understanding of historic earthquakes, seismic hazard and risk (e.g., Bilham, 2015; Hough, 2015 ). Important questions surrounding the earthquake and its regional setting thus arise. What were the detailed characteristics of the rupture and the aftershock sequence, and what is the relationship between mainshock slip and subsequent seismicity? Why did this event not rupture to the surface? Was damage less than should have been expected; and if so, why? What role did path effects, such as basin amplification, play? Do details of the earthquake sequence allow us to better understand regional seismotectonics, and in turn, future risk? Discussion of these and other issues has been ongoing since the earthquake; a large body of literature already exists that characterizes details of the earthquake sequence and its effects. This special issue attempts to gather a wide variety of detailed studies that wholly characterize this event to a degree that has not yet been possible. The studies herein provide an improved understanding of the Gorkha earthquake, its impact on the region, and its place in the broader seismotectonic history of the Himalayan Front.

Gorkha↗
USGS1997

Safety of formalin treatments on warm- and coolwater fish eggs

Formalin is widely used for treating fungal infections of fish eggs in intensive aquaculture operations. The use of formalin in the United States is only allowed on salmonid and esocid eggs unless a special exemption is granted for use on other species. This study was conducted to determine the safety of formalin treatments on eggs of representative warm- and coolwater fish species and data was used to support a request to allow the use of formalin on the eggs of warmwater and additional coolwater fish species. Non-eyed eggs of walleye ( Stizostedion vitreum ), common carp ( Cyprinus carpio ), white sucker ( Catostomus commersoni ), channel catfish ( Ictalurus punctatus ), and lake sturgeon ( Acipenser fulvescens ) were cultured in miniature egg hatching jars and treated for 45 min every-other-day with 1500, 4500, or 7500 μL L -1 formalin up to hatch. For all species tested, the percent hatch was greater in 1500 mu L L-1 treatment groups than in untreated controls. Walleye eggs were the least sensitive species and had a hatch of 87% in the 7500 mu L L-1 treatment. Lake sturgeon were the most sensitive species with a mean hatch of 54% in 1500 mu L L-1 treatments. Adequate margins of safety exist for standard treatments (1500 mu L L-1 for 15 min) on eggs of all species tested except lake sturgeon. Fungal infections drastically reduced or eliminated hatch in most control groups whereas most treated groups were free of infections. This confirms the efficacy of formalin as an fungicide. Published by Elsevier Science B.V.

Aquaculture↗
USGS2003

Lake-specific responses to elevated atmospheric nitrogen deposition in the Colorado Rocky Mountains, U.S.A

We explored variability among subalpine lakes sharing very similar climate and atmospheric conditions, but differing in watershed characteristics, hydrology, and food web structure. Special attention was given to nitrogen (N) dynamics because the study area receives some of the highest levels of atmospheric N deposition in the Rocky Mountains. We asked if the effect of regional N deposition would be manifested uniformly among neighboring lakes both in terms of ambient conditions and responses to greater nutrient inputs. Catchment vegetation appeared to be the main determinant of ambient nitrate (NO 3 ), phosphate (PO 4 ), and dissolved organic carbon (DOC) concentrations, although in-lake differences in recycling produced variable and contrasting NH 4 levels. Phytoplankton chlorophyll a temporarily responded to early season NO 3 peaks in the lakes with rocky watersheds, but chlorophyll means over the ice-free season were remarkably similar among lakes despite differences in both nutrient supply and zooplankton grazing. In most cases, phosphorus was limiting to phytoplankton growth, although the importance of N deficiencies was greater in lakes with forested watersheds and fringing wetlands.

Colorado↗