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At least 145 records · Page 8Linked to original sources
USGS1904

A reconnaissance in northern Alaska across the Rocky Mountains, along Koyukuk, John, Anaktuvuk, and Colville Rivers, and the Arctic coast to Cape Lisburne, in 1901, with notes

Since 1898 the United States Geological Survey has been carrying on systematic topographic and geologic surveys in Alaska under an appropriation made for the investigation of the mineral resources of the Territory. This work has included not only areal surveys of regions already being developed by the miner and prospector, but also explorations and investigations of regions that are little known or entirely unexplored. As a result of these explorations a network of reconnaissance traverses has been extended over a large part of Alaska, where route surveys of this character must necessarily precede more detailed topographic and geologic mapping. They serve to outline the main geographic features of the country and afford the pioneer or prospector a guide for his journeys as well as help him to select his field of operations. The present report and maps are the results of such an investigation.

Alaska↗
USGS2024

Induced seismicity strategic vision

Executive Summary The U.S. Geological Survey has a long history of contributions to the understanding and resolution of various scientific questions related to earthquakes associated with human activities, referred to as induced seismicity. Work started with the Rocky Mountain Arsenal studies in the 1960’s (Healy and others, 1968) when it was first discovered that fluid waste-disposal operations can cause earthquakes. U.S. Geological Survey work on induced seismicity continued in the intervening years but expanded dramatically in the early 2010s. Disposal of large volumes of wastewater, a byproduct of oil and gas production, into the subsurface caused an exponential increase in earthquakes in the central United States, including earthquakes that caused damage to buildings and infrastructure in nearby communities. Established in 2012 within the Earthquake Hazards Program (EHP), the Induced Seismicity Project (ISP) examines earthquakes that are induced by human activities to assess and mitigate the hazards associated with induced earthquakes as well as understand the conditions and processes controlling induced and natural earthquake generation and recurrence. The ISP examines instances of suspected induced earthquakes, in real-time and retrospectively, to assess the probabilistic hazard and investigate possibilities for reducing that hazard, something currently not possible with natural earthquake activity. The ISP has many synergies with work across multiple areas of EHP, including earthquake monitoring, hazard mitigation, and fundamental research into earthquake processes. The overarching questions that guided the development of our research strategies and approaches are as follows: How can seismicity that is induced by industrial activities be better distinguished from natural processes, particularly in regions with higher rates of natural seismicity? Can faults that may be at increased hazard for induced seismicity be identified based on existing fault structures, past earthquake activity, local stress conditions, or other information? What geologic and operational conditions control the occurrence, spatial and temporal evolution, maximum magnitude, ground shaking, and other characteristics of induced seismic sequences? What roles do surface and subsurface deformation, aseismic slip, and other processes play in the occurrence of injection-induced earthquakes? How can induced seismicity be better forecasted to support the Nation’s energy production and climate mitigation goals while limiting related earthquake hazards? In this report, background on induced seismicity and an overview of the state of knowledge is provided in three topical task areas: (1) oil and gas, (2) geothermal, and (3) geologic CO2 sequestration. This report then presents the EHP’s goals, strategies, and approaches—primarily focused on work in the ISP—for understanding the conditions that lead to induced seismicity, mitigating the associated hazards, and assisting the Nation in meeting its future needs in energy production and mitigation of climate change. Finally, the key limitations and opportunities for innovation are outlined at the end of the report.

Circular↗
USGS2006

Lessons learned from the U.S. Geological Survey abandoned mine lands initiative: 1997-2002

Growth of the United States has been facilitated, in part, by hard-rock mining in the Rocky Mountains. Abandoned and inactive mines cause many significant environmental concerns in hundreds of watersheds. Those who have responsibility to address these environmental concerns must have a basic level of scientific information about mining and mine wastes in a watershed prior to initiating remediation activities. To demonstrate what information is needed and how to obtain that information, the U.S. Geological Survey implemented the Abandoned Mine Lands (AML) Initiative from 1997 to 2002 with demonstration studies in the Boulder River watershed in Montana and the Animas River watershed in Colorado. The AML Initiative included collection and analysis of geologic, hydrologic, geochemical, geophysical, and biological data. The synergy of this interdisciplinary analysis produced a perspective of the environmental concerns that could not have come from a single discipline. Two examples of these perspectives include (1) the combination of hydrological tracer techniques, structural geology, and geophysics help to understand the spatial distribution of loading to the streams in a way that cannot be evaluated by monitoring at a catchment outlet, and (2) the combination of toxicology and hydrology combine to illustrate that seasonal variability of toxicity conditions occurs. Lessons have been learned by listening to and collaborating with land-management agencies to understand their needs and by applying interdisciplinary methods to answer their questions.

Colorado, Montana↗
USGS2009

U.S. Geological Survey research in Handcart Gulch, Colorado—An alpine watershed with natural acid-rock drainage

Handcart Gulch is an alpine watershed along the Continental Divide in the Colorado Rocky Mountain Front Range. It contains an unmined mineral deposit typical of many hydrothermal mineral deposits in the intermountain west, composed primarily of pyrite with trace metals including copper and molybdenum. Springs and the trunk stream have a natural pH value of 3 to 4. The U.S. Geological Survey began integrated research activities at the site in 2003 with the objective of better understanding geologic, geochemical, and hydrologic controls on naturally occurring acid-rock drainage in alpine watersheds. Characterizing the role of groundwater was of particular interest because mountain watersheds containing metallic mineral deposits are often underlain by complexly deformed crystalline rocks in which groundwater flow is poorly understood. Site infrastructure currently includes 4 deep monitoring wells high in the watershed (300– 1,200 ft deep), 4 bedrock (100–170 ft deep) and 5 shallow (10–30 ft deep) monitoring wells along the trunk stream, a stream gage, and a meteorological station. Work to date at the site includes: geologic mapping and structural analysis; surface sample and drill core mineralogic characterization; geophysical borehole logging; aquifer testing; monitoring of groundwater hydraulic heads and streamflows; a stream tracer dilution study; repeated sampling of surface and groundwater for geochemical analyses, including major and trace elements, several isotopes, and groundwater age dating; and construction of groundwater flow models. The unique dataset collected at Handcart Gulch has yielded several important findings about bedrock groundwater flow at the site. Most importantly, we find that bedrock bulk permeability is nontrivial and that bedrock groundwater apparently constitutes a substantial fraction of the hydrologic budget. This means that bedrock groundwater commonly may be an underappreciated component of the hydrologic system in studies of alpine watersheds. Additionally, despite the complexity of the fracture controlled aquifer system, it appears that it can be represented with a relatively simple conceptual model and can be treated as an equivalent porous medium at the watershed scale. Interpretation of existing data, collection of new monitoring data, and efforts to link geochemical and hydrologic processes through modeling are ongoing at the site.

Colorado↗
USGS2010

Evaluation of the extent of contamination caused by historical mining in catchments of central Colorado

The U.S. Geological Survey conducted an assessment of stream water and sediment quality in central Colorado, an area of about 54,000 km2. The study area is focused on small tributary catchments in the Rocky Mountains. The Colorado Mineral belt, a northeast-trending mineralized zone that experienced base- and precious-metal mining at the beginning of the late 1800s and early 1900s, cuts diagonally across the geologic trend in the study area. The goal of this study was to compare water and sediment quality in background catchments with those which have been mined. Water and sediment data from 200 catchments, and data from macroinvertebrates from more than 100 catchments, provided ample data for evaluation of the effects of mining on water and sediment quality. Focused sampling was conducted during low-flow conditions in the summers of 2004-2007. Samples were collected from catchments that (1) were underlain largely by a single lithologic unit, (2) contained hydrothermally altered rock and had been prospected, and (3) contained historical mines. Geochemical data determined from catchments that did not contain hydrothermal alteration or historical mines met water-quality criteria and recommended sediment-quality guidelines and showed small variations in base-metal concentrations. Hydrothermal alteration and mineralization typically are associated with igneous rocks that have intruded older bedrock. Base-metal concentrations were elevated in sediment from catchments underlain by hydrothermally altered rock. Catchments affected by historical mining contained highly elevated base-metal concentrations. Classification of catchments on the basis of mineral deposit types proved to be an efficient and accurate method for discriminating catchments that had degraded water and sediment quality. Only about 4.5 percent of the study area has been affected by historical mining, whereas a larger portion of the study area is underlain by hydrothermally altered rock. Weathering of QSP-altered catchments release metals and result in naturally elevated geochemical background concentrations in both sediment and water. The presence of hydrothermal alteration is shown to be a major consideration in the selection of sites for the determination of geochemical background.

Conference Paper↗
USGS2010

Reported Historic Asbestos Mines, Historic Asbestos Prospects, and Other Natural Occurrences of Asbestos in Oregon and Washington

This map and its accompanying dataset provide information for 51 natural occurrences of asbestos in Washington and Oregon, using descriptions found in the geologic literature. Data on location, mineralogy, geology, and relevant literature for each asbestos site are provided. Using the map and digital data in this report, the user can examine the distribution of previously reported asbestos occurrences and their geological characteristics in the Pacific Northwest States of Washington and Oregon. This report is part of an ongoing study by the U.S. Geological Survey to identify and map reported natural asbestos occurrences in the United States, which thus far includes similar maps and datasets of natural asbestos occurrences within the Eastern United States (http://pubs.usgs.gov/of/2005/1189/), the Central United States (http://pubs.usgs.gov/of/2006/1211/), the Rocky Mountain States (http://pubs.usgs.gov/of/2007/1182/), and the Southwestern United States (http://pubs.usgs.gov/of/2008/1095/). These reports are intended to provide State and local government agencies and other stakeholders with geologic information on natural occurrences of asbestos in the United States.

Open-File Report↗
USGS1997

Precious metals associated with Late Cretaceous-early Tertiary igneous rocks of southwestern Alaska

Placer gold and precious metal-bearing lode deposits of southwestern Alaska lie within a region 550 by 350 km, herein referred to as the Kuskokwim mineral belt. This mineral belt has yielded 100,240 kg (3.22 Moz) of gold, 12, 813 kg (412,000 oz) of silver, 1,377,412 kg (39,960 flasks) of mercury, and modest amounts of antimony and tungsten derived primarily from the late Cretaceous-early Tertiary igneous complexes of four major types: (1) alkali-calcic, comagmatic volcanic-plutonic complexes and isolated plutons, (2) calc-alkaline, meta-aluminous reduced plutons, (3) peraluminous alaskite or granite-porphyry sills and dike swarms, and (4) andesite-rhyolite subaerial volcanic rocks. About 80 percent of the 77 to 52 Ma intrusive and volcanic rocks intrude or overlie the middle to Upper Cretaceous Kuskokwim Group sedimentary and volcanic rocks, as well as the Paleozoic-Mesozoic rocks of the Nixon Fork, Innoko, Goodnews, and Ruby preaccretionary terranes. The major precious metal-bearing deposit types related to Late Cretaceous-early Tertiary igneous complexes of the Kuskokwim mineral belt are subdivided as follows: (1) plutonic-hosted copper-gold polymetallic stockwork, skarn, and vein deposits, (2) peraluminous granite-porphory-hosted gold polymetallic deposits, (3) plutonic-related, boron-enriched silver-tin polymetallic breccia pipes and replacement deposits, (4) gold and silver mineralization in epithermal systems, and (5) gold polymetallic heavy mineral placer deposits. Ten deposits genetically related to Late Cretaceous-early Tertiary intrusions contain minimum, inferred reserves amounting to 162,572 kg (5.23 Moz) of gold, 201,015 kg (6.46 Moz) silver, 12,160 metric tons (t) of tin, and 28,088 t of copper. The lodes occur in veins, stockworks, breccia pipes, and replacement deposits that formed in epithermal to mesothermal temperature-pressure conditions. Fluid inclusion, isotopic age, mineral assemblage, alteration assemblage, and structural data indicate that many of the mineral deposits associated with Late Cretaceous-early tertiary volcanic and plutonic rocks represent geologically and spatially related, vertically zoned hydrothermal systems now exposed at several erosional levels. Polymetallic gold deposits of the Kuskokwim mineral belt are probably related to 77 to 52 Ma plutonism and volcanism associated with a period of rapid, north-directed subduction of the Kula plate. The geologic interpretation suggests that igneous complexes of the Kuskokwim mineral belt formed in an intracontinental back-arc setting during a period of extensional, wrench fault tectonics. The Kuskokwim mineral belt has many geologic and metallogenic features similar to other precious metal-bearing systems associated with arc-related igneous rocks such as the Late Cretaceous-early Tertiary Rocky Mountain alkalic province, the Jurassic Mount Milligan district of central British Columbia, the Andean orogen of South America, and the Okhotsk-Chukotka belt of northeast Asia.

Alaska↗
USGS1995

Ground Water Atlas of the United States: Segment 2, Arizona, Colorado, New Mexico, Utah

This chapter of the Ground Water Atlas of the United States describes the aquifers in Arizona, Colorado, New Mexico, and Utah. These four States, which comprise Segment 2 of this Atlas, are located in the Southwestern United States and extend from the rolling grasslands of the Great Plains on the east across the Rocky Mountains and Continental Divide to the desert basins of the Southwest. The 425,000-square-mile area ranges in altitude from about 14,400 feet above sea level in the Rocky Mountains of Colorado to about 100 feet near the lower Colorado River in southwestern Arizona. All the ground water in Segment 2 ultimately is derived from infiltration of precipitation, which varies considerably with the altitude and topography of the area. The Great Plains Physiographic Province of the Central United States extends into eastern Colorado and New Mexico (fig. 1), where flat to rolling prairie (fig. 2) with scattered hills and bluffs gradually rises westward to 5,000 to 7,000 feet above sea level and abruptly gives way to the frontal ranges of the Rocky Mountains in the Southern Rocky Mountain and Basin and Range Physiographic Provinces. West of the frontal ranges in Colorado and northern New Mexico are additional and higher mountain ranges generally oriented north-south but with many spurs and extensions oriented in other directions. The many ranges of the Rocky Mountains are separated by valleys and high mountain parks (fig. 3). Colorado contains about three-fourths of the Nation's land area above 10,000 feet and has 53 mountain peaks higher than 14,000 feet. Most of these high peaks are located near the Continental Divide (fig. 1), which extends approximately north-south through central Colorado and western New Mexico. The altitude of the divide decreases in southern New Mexico to less than 4,500 feet in a few areas. Farther westward, the mountains are less prevalent and are interspersed with broad structural basins. These basins and the broad valleys of the middle Colorado River and its tributaries form the irregular intermontane topography of the Colorado Plateaus Physiographic Province (fig. 4). Plateaus and high mesas are formed where the surface has been dissected by rugged canyons carved by the Colorado River and its tributaries (fig. 5). The largest of these canyons-the Grand Canyon-extends about 220 miles southwestward from the mouth of the Little Colorado River in Arizona and ranges from 4 to 18 miles in width and from 2,700 to 5,700 feet in depth below the rim. Small mountain ranges and intervening broad desert valleys of the Basin and Range Physiographic Province are prevalent to the west and south of the Colorado Plateaus in western Utah, southern Arizona, and southern New Mexico (fig. 1). These mountain ranges generally protrude 3,000 to 6,000 feet above the surrounding valley floor (fig. 6) and commonly extend from 20 to 50 miles in a north or northwesterly direction. Small parts of the Middle Rocky Mountains and Wyoming Basin Physiographic Provinces extend into northwestern Colorado and northeastern Utah (fig. 1). The topography, geology, and hydrology of the two areas are described in Chapter 1 of this Atlas. Four of the Nation's major river systems have headwaters in the mountainous areas of Segment 2. The South Platte River of the Missouri River system drains the eastern slope of northern Colorado; the Arkansas River and its tributary, the Canadian River, drain southeastern Colorado and northeastern New Mexico; the Rio Grande and its tributary, the Pecos River, drain south-central Colorado and central New Mexico; and the Colorado River and its tributaries drain Arizona, eastern Utah, Northwestern New Mexico, and western Colorado (fig. 1). Western Utah is drained by numerous streams that terminate in local desert basins, the Great Salt Lake, or other local lakes and reservoirs. Because the Great Salt Lake lies in the Great Basin, which is the largest closed basin in North America, it has no outlet to the sea. The salinity of the lake water is about 20 percent or about 6 times the salinity of seawater. Most of Segment 2 is sparsely populated. The average population density of counties is less than 8 persons per square mile in about 65 percent of the four-State area (fig. 7). Population densities range from less than 0.5 person per square mile in a few rural counties to more than 4 ,000 persons per square mile in populous urban areas. The 1990 population of the four States was about 10 million; almost 70 percent of this population was in Arizona and Colorado. Most land in Segment 2 is undeveloped forest grassland, or desert shrubland, much of which is used for livestock grazing. Land used for production of commercial crops primarily is in eastern Colorado and eastern New Mexico.

Arizona, Colorado, New Mexico, Utah↗
USGS1983

Hydrology of area 54, northern Great Plains, and Rocky Mountain coal provinces, Colorado and Wyoming

A nationwide need for information characterizing hydrologic conditions in mined and potential mine areas has become paramount with the enactment of the Surface Mining Control and Reclamation Act of 1977. This report, one in a series covering the coal provinces nationwide, presents information thematically by describing single hydrologic topics through the use of brief texts and accompanying maps, graphs, or other illustrations. The summation of the topical discussions provides a description of the hydrology of the area. Area 54, in north-central Colorado and south-central Wyoming, is 1 of 20 hydrologic reporting areas of the Northern Great Plains and Rocky Mountain coal provinces. Part of the Southern Rocky Mountains and Wyoming Basin physiographic provinces, the 8,380-square-mile area is one of contrasting geology, topography, and climate. This results in contrasting hydrologic characteristics. The major streams, the North Platte, Laramie, and Medicine Bow Rivers, and their principal tributaries, all head in granitic mountains and flow into and through sedimentary basins between the mountain ranges. Relief averages 2,000 to 3,000 feet. Precipitation in the mountains may exceed 40 inches annually, much of it during the winter, which produces deep snowpacks. Snowmelt in spring and summer provides most streamflow. Precipitation in the basins averages 10 to 16 inches annually, insufficient for sustained streamflow; thus, streams originating in the basins are ephemeral. Streamflow quality is best in the mountains where dissolved-solids concentrations generally are least. These concentrations increase as streams flow through sedimentary basins. The increases are mainly natural, but some may be due to irrigation in and adjacent to the flood plains. In the North Platte River, dissolved-solids concentrations are usually less than 300 milligrams per liter; in the Laramie and the Medicine Bow Rivers, the concentrations may average 500 to 850 milligrams per liter. However, water-quality stations on the Laramie and the Medicine Bow Rivers are farther removed from the mountain sources than the stations in the North Platte drainage. Because of the semiarid climate of the basins, soils are not adequately leached. Consequently, flow in ephemeral streams usually has a larger concentration of dissolved solids than that in perennial streams, averaging 1,000 to 1,600 milligrams per liter. Aquifers containing usable ground water are combined into three groups: (1) consolidated and unconsolidated non-coal-bearing Quaternary and Upper Tertiary deposits, (2) Mesozoic and Paleozoic sedimentary rocks, and (3) Lower Tertiary and Upper Cretaceous sedimentary rocks containing coal. These aquifers are used for municipal, domestic, irrigation, and stock supplies. Well yields range from about 5 to 1,000 gallons per minute, and depend on type of aquifer, saturated thickness, and degree of fracturing. The best quality ground water usually comes from the non-coal-bearing Quaternary and Upper Tertiary rocks or the Mesozoic and Paleozoic rocks; often it is dominated by calcium and bicarbonate ions. The coal-bearing formations have a large variability in water chemistry; dominant ions may be bicarbonate or sulfate and sodium, calcium, or magnesium. Dissolved-solids concentrations are generally larger than in the former two groups. The U.S. Geological Survey operates a network of hydrologic stations to observe the streamflow and groundwater conditions. This network currently includes 31 surface-water stations and 35 observation wells; information is available for many other sites observed in the past. Data available include rate of flow, water levels, and water quality; much of the data are available in published reports or from computer storage through the National Water Data Exchange (NAWDEX) or the National Water Data Storage and Retrieval System (WATSTORE). Five formations of Late Cretaceous and early Tertiary age contain coal.

Colorado, Wyoming↗
USGS1997

Seasonal variation in metal concentrations in a stream affected by acid mine drainage, St. Kevin Gulch, Colorado

Mining of mineral deposits in the Rocky Mountains has left a legacy of acidic inflows to otherwise pristine upland watersheds. Since 1986, the U.S. Geological Survey has studied physical, chemical, and biological processes that affect the transport and transformation of metals in St. Kevin Gulch, an acidic, metal-rich stream near Leadville, Colorado. Well-known chemical processes have been quantified in the context of on-going physical transport by defining the hydrology with instream tracer-dilution experiments. These processes affect the partitioning of metals between dissolved and colloidal transport phases. In this acidic stream, pH increases during snowmelt runoff. At the most acidic stream site, pH varies from 3.15 to 4.00 during seasonal changes. Conservative effects of dilution are quantified using manganese as a natural, conservative tracer. Aluminum, copper, and zinc also are relatively conservative throughout the seasonal changes. Sulfate and iron, on the other hand, are removed with respect to manganese. The loss of iron through precipitation of hydrous Fe oxide is consistent with thermodynamic calculations. The loss of sulfate, however, cannot be fully explained.

Colorado↗
USGS2001

Knickzone propagation in the Black Hills and northern High Plains: A different perspective on the late Cenozoic exhumation of the Laramide Rocky Mountains

Geomorphic research in the Black Hills and northern High Plains poses an intriguing hypothesis for the Cenozoic evolution of this salient of the Laramide Rockies. Most recently, geologists have appealed to late Cenozoic epeirogenic uplift or climate change to explain the post-Laramide unroofing of the Rockies. On the basis of field mapping and the interpretation of long-valley profiles, we conclude that the propagation of knickzones is the primary mechanism for exhumation in the Black Hills. Long profiles of major drainages show discrete breaks in the slope of the channel gradient that are not coincident with changes in rock type. We use the term knickzones to describe these features because their profiles are broadly convex over tens of kilometers. At and below the knickzone, the channel is incising into bedrock, abandoning a flood plain, and forming a terrace. Above the knickzone, the channel is much less incised, resulting in a broad valley bottom. Numerous examples of stream piracy are documented, and in each case, the capture is recorded in the same terrace level. These observations are consistent with migrating knickzones that have swept through Black Hills streams, rearranging drainages in their wake. We demonstrate there are two knickzone fronts associated with mapped terraces. Preliminary field evidence of soil development shows that these terraces are time transgressive in nature. Our data strongly suggest that knickzone propagation must be considered a viable mechanism driving late Cenozoic fluvial incision and exhumation of the northern High Plains and adjacent northern Rocky Mountains.

South Dakota, Wyoming↗
USGS1970

Origin of the disturbed belt in northwestern Montana

The northern part of the disturbed belt in Montana is a northwesterly trending zone of closely spaced westerly dipping thrust faults, many folds, and some longitudinal normal faults and transverse faults. The theory of vertical uplift that results in gravitational gliding is a reasonable explanation of the origin of the disturbed belt of northwestern Montana. The outcropping sedimentary rocks range in age from Precambrian (Belt Supergroup) to Tertiary. All Precambrian, Paleozoic, and Mesozoic stratigraphic rock units thin markedly to the east. Westernmost Montana was a slowly subsiding geosynclme during Precambrian (Belt) sedimentation and a miogeosyncline during much of Paleozoic sedimentation. The miogeosynclinal area was uplifted into a highland during the Jurassic and Cretaceous, and sediment from the highland was deposited in a basin to the east. Periodic uplift and erosion continued through Cretaceous and very early Tertiary. I believe that a décollement was established, in the easterly tilted sediments, and the mass moved eastward under the influence of gravity across the small Mesozoic basin. The décollement migrated upsection to the east. East of the slide mass the rocks were folded, marking the east edge of the northern part of the disturbed belt in Montana. This edge was probably controlled by the erosional edge of the Precambrian (Belt) rocks and the west side of the craton. Additional uplift continued to produce sliding that piled one fault block upon another. The minimum amount of shortening of this upper part of the crust by thrust faulting and folding computed along one line of section is more than 29 miles. The amount of uplift to the west very likely exceeded 45,000 ft during the period from very Late Cretaceous to late Eocene. The main décollement was under an overburden of as much as 25,000 ft of strata—a thickness that would probably permit abnormal fluid pressures to develop in mudstone. The slope of the strata and glide surface by the end of uplift may have been as much as 8.5°. Large Basin-and-Range-type normal faults developed, after thrusting, between the area of maximum uplift and the thrust fault belt. The westernmost of these faults formed the graben and horsts in the Rocky Mountain trench. The total amount of displacement of the normal faults along one line of section is about 43,000 ft. The total thickness of strata eroded from the area of maximum uplift is about 45,000 ft. The theory of vertical uplift and gravitational sliding may also be applicable to the disturbed belt in Alberta and British Columbia. The disturbed belt, Rocky Mountain trench, and areas of uplift are continuous from northwestern Montana to northern British Columbia. Much of the geologic history of western Alberta and eastern British Columbia is like that of northwestern Montana.

Montana↗
USGS2004

Quaternary stratigraphy and tectonics, and late prehistoric agriculture of the Safford Basin (Gila and San Simon river valleys), Graham County, Arizona

This guidebook accompanied the 46th annual meeting of the Rocky Mountain Cell of the Friends of the Pleistocene (FOP) and the 2002 Fall Field Trip of the Arizona Geological Society. The meeting and field trip were held in the Safford Basin, southeastern Arizona. The Friends of the Pleistocene is an informal gathering of Quaternary geologists, geomorphologists, and pedologists who meet annually for a field conference. The first part of the guidebook consists of road logs with descriptions of stops covering the three days of the field trip. An overview of the geology of the Safford Basin is given in Stop 1-1. The second part of the guidebook consists of four short papers that discuss adjacent areas or that expand upon the road log descriptions of the field trip stops. The first paper by Reid and Buffler is a summary of upper Cenozoic depositional facies in the Duncan Basin, the first basin to the east of the Safford Basin. The next three papers expand upon (1) the soil study of the gridded field agricultural complex (Stop 2-3, Homburg and Sandor), (2) the vertebrate fossils of the San Simon Valley in the southeastern part of the Safford Basin (Stop 3-1, Thrasher), and (3) paleoIndian irrigation systems and settlements in Lefthand Canyon at the foot of the Pinaleno Mountains (Stop 3-2, Neely and Homburg).

Open-File Report↗
USGS1877

Geology of the Henry Mountains

If these pages fail to give a correct account of the structure of the Henry Mountains the fault is mine and I have no excuse. In all the earlier exploration of the Rocky Mountain Region, as well as in much of the more recent survey, the geologist has merely accompanied the geographer and has had no voice in the determination of either the route or the rate of travel. When the structure of a mountain was in doubt he was rarely able to visit the points which should resolve the doubt, but was compelled to turn regretfully away. Not so in the survey of the Henry Mountains. Geological exploration had shown that they were well disposed for examination, and that they promised to give the key to a type of structure which was at best obscurely known; and I was sent by Professor Powell to make a study of them, without restriction as to my order or method. I was limited only in time, the snow stopping my work two months after it was begun. Two months would be far too short a period in which to survey a thousand square miles in Pennsylvania or Illinois, but among the Colorado Plateaus it proved sufficient. A few comprehensive views from mountain tops gave the general distribution of the formations, and the remainder of the time was spent in the examination of the localities which best displayed the peculiar features of the structure. So thorough was the display and so satisfactory the examination, that in preparing my report I have felt less than ever before the desire to revisit the field and prove my conclusions by more extended observation.

Utah↗
USGS2006

Pikes Peak, Colorado

For 200 years, Pikes Peak has been a symbol of America's Western Frontier--a beacon that drew prospectors during the great 1859-60 Gold Rush to the 'Pikes Peak country,' the scenic destination for hundreds of thousands of visitors each year, and an enduring source of pride for cities in the region, the State of Colorado, and the Nation. November 2006 marks the 200th anniversary of the Zebulon M. Pike expedition's first sighting of what has become one of the world's most famous mountains--Pikes Peak. In the decades following that sighting, Pikes Peak became symbolic of America's Western Frontier, embodying the spirit of Native Americans, early explorers, trappers, and traders who traversed the vast uncharted wilderness of the Western Great Plains and the Southern Rocky Mountains. High-quality printed paper copies of this poster are available at no cost from Information Services, U.S. Geological Survey (1-888-ASK-USGS).

General Information Product↗
USGS1996

Summary of biological and contaminant investigations related to stream water quality and environmental setting in the Upper Colorado River basin, 1938-95

As part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) program, an inventory of the biological and contaminant investigations for the Upper Colorado River Basin study unit was conducted. To enhance the sampling design for the biological component of the program, previous studies about the ecology of aquatic organisms and contaminants were compiled from computerized literature searches of biological data bases and by contacting other Federal, State, and local agencies. Biological and contaminant investigations that have been conducted throughout the basin since 1938 were categorized according to four general categories of biological investigations and two categories of contaminant investigations: algal communities, macroinvertebrate communities, fish communities, habitat characterization, contaminants in organism tissue, and contaminants in bed sediment. The studies were identified by their locations in two physiographic provinces, the Southern Rocky Mountains and the Colorado Plateau, and by the predominant land use in the area of the investigation. Studies on algal communities and contaminants in organism tissue and in bed sediment are limited throughout the basin. Studies on macroinvertebrate and fish communities and habitat characterization are the most abundant in the study unit. Natural and human factors can affect biological communities and their composition. Natural factors that affect background water-quality conditions are physiography, climate, geology, and soils. Algae, macroinvertebrates, and fish that are present in the Southern Rocky Mountains and the Colorado Plateau physiographic provinces vary with altitude and physical environment. Green algae and diatoms are predominant in the higher altitude streams, and blue-green, golden-brown, and green algae are predominant in the lower altitude streams. Caddisflies, mayflies, and stoneflies are the dominant macroinvertebrates in the higher altitudes, whereas aquatic worms, leeches, and dragonflies are more common at lower altitudes. Cold-water species, such as trout, are present at the higher altitudes, and warmer water species, such as catfish, carp, and suckers, are predominant at the lower altitudes. Human factors that affect water-quality conditions are mining, urbanization, agriculture, and hydrologic modifications. Mining areas can be depleted of organisms or contain a low diversity of species. Acid-tolerant algae, such as certain species of green algae and diatoms, and metal-tolerant caddisflies can be present in mining areas. Urbanized areas are located in the Southern Rocky Mountains and in the Colorado Plateau and contain species characteristic of the physiographic provinces. Agricultural areas contain species, such as blue-green algae, aquatic worms, suckers, and carp, that can tolerate organic enrichment, sedimentation, and lower concentrations of dissolved oxygen.

Water-Resources Investigations Report↗
USGS2011

Reported historic asbestos mines, historic asbestos prospects, and other natural occurrences of asbestos in California

The map (Plate.pdf), pamphlet (Pamphlet.pdf), and the accompanying datasets in this report provide information for 290 sites in California where asbestos occurs in natural settings, using descriptions found in the geologic literature. Data on location, mineralogy, geology, and relevant literature for each asbestos site are provided. Using the map and digital data in this report, the user can examine the distribution of previously reported asbestos and their geological characteristics in California. This report is part of an ongoing study by the U.S. Geological Survey to identify and map sites where asbestos mineralization occurs in the United States, which includes similar maps and datasets of natural asbestos localities within the Eastern United States (http://pubs.usgs.gov/of/2005/1189/), the Central United States (http://pubs.usgs.gov/of/2006/1211/), the Rocky Mountain States (http://pubs.usgs.gov/of/2007/1182/), the Southwestern United States (http://pubs.usgs.gov/of/2008/1095/), and the Northwestern United States (Oregon and Washington) (http://pubs.usgs.gov/of/2010/1041/). These reports are intended to provide State and local government agencies and other stakeholders with geologic information on reported asbestos mineralization in the United States.

California↗
USGS1962

Quaternary geology of the Bellevue area in Blaine and Camas Counties, Idaho

The Bellevue area covers about 350 square miles of a foothill belt between the Rocky Mountains to the north and the Snake River plains to the south. Complexly deformed impure quartzites and limestones of the Mississippian Milligen and Pennsylvanian-Permian Wood River formations were intruded by large bodies of quartz diorite and granodiorite along regional structures trending northwesterly; the intrusions are part of the Cretaceous Idaho batholith. Erosional remnants of the Challis volcanics, dominantly latitic to andesitic in composition and early(?) to middle Tertiary in age, rest unconformably on the older rocks. A sequence of Pliocene Rhyolitic ash flows and basaltic lava flows unconformably overlies the Challis and older rocks and is in turn unconformably overlain by olivine basalt of late Pliocene or early Quaternary age. The main valleys of the area, partly Erosional and partly structural in origin, are underlaind by late Quaternary olivine basalt flows (Snake River basalt) and intercalated lacustrine, fluvial, proglacial sediments. The Big Wood River, the master stream of the area, flows southward through a narrow steep-sided valley in the mountainous country north of the Bellevue area and debouches into a broad alluvial valley, the Wood River Valley, in the foothill belt. The valley has the shape of an isosceles triangle with a ten mile long, east-west base consisting of a ridge of Pliocene volcanics which separates the valley from the Snake River Plains to the south. The river now flows through a narrow gap in the southwest corner of the triangle. A similar, but wider, gap around the east end of the ridge was formerly occupied by the river. The river has been shifted back and forth between these two gaps at least four times during an interval in which six late Quaternary basalt flows erupted in the Bellevue area. Two of the flows caused direct diversion of the river and another was influential in bringing about a diversion on an aggradational fan upstream from the lava dam. Just prior to the Bull Lake stage the river, flowing out the east gap, was blocked but not diverted by the youngest basalt flow in the Bellevue area. During the proglacial aggradation, the river shifted widely on its fan and spilled alternatively out both the east and west gaps. After the Bull Lake stage, the west gap had an advantageous base level relative to the lava-blocked east gap, and the river cut down in the west gap. After the second, Pinedale, proglacial aggradation in the Wood River Valley, the west gap still maintained an advantageous base level, and the river again cut down in the west outlet valley where it remains today. Periglacial deposits completely dominate the sidestream valleys of the Bellevue area. They formed under a rigorous climate during the Pinedale stage, when slope erosion accelerated by frost activated processes caused aggradation of valley floors by local detritus. Even at present the larger sidestreams are so choked with detritus that the streams have not regained control of their valley floors. Recent basalt, comparable in age to the younger flows of the Craters of the Moon National Monument, spread from a rugged, cratered vent several miles south of the Bellevue area. Using degree of weathering, erosion, and soil development as a basis of comparison, this flow provides and end point for estimating the relative ages of the six late Quaternary flows in the Bellevue area.

Idaho↗