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Research about Coconino County, Arizona

Source-linked reports with geographic coverage including Coconino County, Arizona.

At least 19 recordsLinked to original sources
USGS2024

Using integrated step selection to determine effects of predation risk on bison habitat selection and movement

Animal movement is a fundamental mechanism that shapes communities and ecosystems. Ungulates alter the ecosystems they inhabit and understanding their movements and distribution is critical for linking habitat with population dynamics. Predation risk has been shown to strongly influence ungulate movement patterns, such that ungulates may select habitat where predation risk is lower (refugia), adjust movement rates, temporal patterns, or selection of cover variables in areas with greater predation risk. We evaluated potential predation avoidance behavior in a population of plains bison inhabiting the north rim of Grand Canyon National Park (GRCA) and adjacent Kaibab National Forest (KNF). The KNF has year-round hunting managed by Arizona Game and Fish Department, whereas hunting is not allowed in GRCA. Human-maintained water sources on the KNF are particularly important resources for bison wherein they may be exposed to higher predation risk to access these resources. We used 2-h GPS locations for three years from 31 bison ( n = 9 males; n = 22 females), and integrative step selection analysis to test four hypotheses about the potential for bison to reduce their risk from human predation by avoiding areas of high predation risk; moving faster in areas with high predation risk; entering high-risk areas at night when risk is reduced; and entering high-risk areas in habitats that provide cover (coniferous forest). The highest performing model indicated bison movement was 1.3 times faster per 2-h step interval than in areas with no hunting across all vegetation classes (coniferous forest, shrub, quaking aspen, grass-forb meadow) and across all topography classes (valley, slope, ridge). Bison moved more slowly in grass-forb meadows than all other vegetation types, and in valleys relative to slopes and ridges. Several radio-collared individuals had no GPS locations in KNF for the duration of the study. Bison avoided predation risk using two strategies: moving faster while in the KNF, and fully avoiding high-risk areas by remaining within GRCA. Management that manipulates or reduces timing of hunting seasons may reduce perceived predation risk and encourage bison to distribute into the KNF and across a broader range of available habitat.

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USGS2022

Gravity surveys for estimating possible width of enhanced porosity zones across structures on the Coconino Plateau, Coconino County, north-central Arizona

The U.S. Geological Survey completed gravity transects in 2015, 2018, and 2019 over four features: the Bright Angel Fault, Bright Angel Monocline, Tusayan Graben, and Redlands Ranch Fault Zone in the Coconino Plateau, Coconino County, Arizona, to determine if the existence and width of high porosity (low density) zones could be inferred from the resulting gravity contrasts, which could be used to update groundwater models of the region. Faults and other geological structures in the Coconino Plateau are commonly thought to play a role in the movement of groundwater in the area, but limited data exist to constrain their influence. Some groundwater models of the region have used zones of enhanced permeability and porosity along or near features to model their effect on groundwater flow but have not shown sensitivity to the width of the zones used. Enhanced porosity zones in the subsurface, such as those included along or near features in some groundwater models of the region, could create small mass deficiencies detectable by microgravity methods. However, 3 of the 4 gravity transects, the Bright Angel Fault, Bright Angel Monocline, and Tusayan Graben, showed no negative gravity anomaly over the features that could indicate the presence of a low-density zone. Only the Redlands Ranch Fault Zone that had nearby collapse features showed a negative gravity anomaly that was modeled as a zone of 0.017 increased porosity about 800 meters wide, corresponding to the relative dimension and enhanced porosity used in groundwater models of the area. This study was unable to verify the existence of enhanced porosity zones at the selected locations along the other features. However, faults and other features may affect groundwater flow in different ways at different locations, and this work does not preclude the existence of enhanced porosity zones at other places along these faults.

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USGS2017

Pre-mining trace element and radiation exposure to biota from a breccia pipe uranium mine in the Grand Canyon (Arizona, USA) watershed

The risks to wildlife and humans from uranium (U) mining in the Grand Canyon watershed are largely unknown. In addition to U, other co-occurring ore constituents contribute to risks to biological receptors depending on their toxicological profiles. This study characterizes the pre-mining concentrations of total arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni), selenium (Se), thallium (Tl), U, and zinc (Zn); radiation levels; and histopathology in biota (vegetation, invertebrates, amphibians, birds, and mammals) at the Canyon Mine. Gross alpha levels were below the reporting limit (4 pCi/g) in all samples, and gross beta levels were indicative of background in vegetation (<10–17 pCi/g) and rodents (<10–43.5 pCi/g). Concentrations of U, Tl, Pb, Ni, Cu, and As in vegetation downwind from the mine were likely the result of aeolian transport. Chemical concentrations in rodents and terrestrial invertebrates indicate that surface disturbance during mine construction has not resulted in statistically significant spatial differences in fauna concentrations adjacent to the mine. Chemical concentrations in egg contents and nestlings of non-aquatic birds were less than method quantification limits or did not exceed toxicity thresholds. Bioaccumulation of As, Pb, Se, Tl, and U was evident in Western spadefoot ( Spea multiplicata ) tadpoles from the mine containment pond; concentrations of As (28.9–31.4 μg/g) and Se (5.81–7.20 μg/g) exceeded toxicity values and were significantly greater than in tadpoles from a nearby water source. Continued evaluation of As and Se in biota inhabiting and forging in the mine containment pond is warranted as mining progresses.

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USGS2016

Element concentrations in surface soils of the Coconino Plateau, Grand Canyon region, Coconino County, Arizona

This report provides the geochemical analyses of a large set of background soils collected from the surface of the Coconino Plateau in northern Arizona. More than 700 soil samples were collected at 46 widespread areas, sampled from sites that appear unaffected by mineralization and (or) anthropogenic contamination. The soils were analyzed for 47 elements, thereby providing data on metal concentrations in soils representative of the plateau. These background concentrations can be used, for instance, for comparison to metal concentrations found in soils potentially affected by natural and anthropogenic influences on the Coconino Plateau in the Grand Canyon region of Arizona. The soil sampling survey revealed low concentrations for the metals most commonly of environmental concern, such as arsenic, cobalt, chromium, copper, mercury, manganese, molybdenum, lead, uranium, vanadium, and zinc. For example, the median concentrations of the metals in soils of the Coconino Plateau were found to be comparable to the mean values previously reported for soils of the western United States.

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USGS2014

Geologic map of the eastern quarter of the Flagstaff 30’ x 60’ quadrangle, Coconino County, northern Arizona

The eastern quarter of the Flagstaff 30′ x 60′ quadrangle includes eight USGS 1:24,000-scale quadrangles in Coconino County, northern Arizona (fig. 1, map sheet): Anderson Canyon, Babbitt Wash, Canyon Diablo, Grand Falls, Grand Falls SE, Grand Falls SW, Grand Falls NE, and Meteor Crater. The map is bounded by lat 35° to 35°30′ N. and long 111° to 111°15′ W. and is on the southern part of the Colorado Plateaus geologic province (herein Colorado Plateau). Elevations range from 4,320 ft (1,317 m) at the Little Colorado River in the northwest corner of the map area to about 6,832 ft (2,082 m) at the southwest corner of the map. This geologic map provides an updated geologic framework for the eastern quarter of the Flagstaff 30′ x 60′ quadrangle and is adjacent to two other recent geologic maps, the Cameron and Winslow 30′ x 60′ quadrangles (Billingsley and others, 2007, 2013). This geologic map is the product of a cooperative effort between the U.S. Geological Survey (USGS) and the Navajo Nation. It provides geologic information for resource management officials of the U.S. Forest Service, the Arizona Game and Fish Department, and the Navajo Nation Reservation (herein the Navajo Nation). Funding for the map was provided by the USGS geologic mapping program, Reston, Virginia. Field work on the Navajo Nation was conducted under a permit from the Navajo Nation Minerals Department. Any persons wishing to conduct geologic investigations on the Navajo Nation must first apply for, and receive, a permit from the Navajo Nation Minerals Department, P.O. Box 1910, Window Rock, Arizona 86515, telephone (928) 871-6587.

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USGS2014

Exposure pathways and biological receptors: baseline data for the canyon uranium mine, Coconino County, Arizona

Recent restrictions on uranium mining within the Grand Canyon watershed have drawn attention to scientific data gaps in evaluating the possible effects of ore extraction to human populations as well as wildlife communities in the area. Tissue contaminant concentrations, one of the most basic data requirements to determine exposure, are not available for biota from any historical or active uranium mines in the region. The Canyon Uranium Mine is under development, providing a unique opportunity to characterize concentrations of uranium and other trace elements, as well as radiation levels in biota, found in the vicinity of the mine before ore extraction begins. Our study objectives were to identify contaminants of potential concern and critical contaminant exposure pathways for ecological receptors; conduct biological surveys to understand the local food web and refine the list of target species (ecological receptors) for contaminant analysis; and collect target species for contaminant analysis prior to the initiation of active mining. Contaminants of potential concern were identified as arsenic, cadmium, chromium, copper, lead, mercury, nickel, selenium, thallium, uranium, and zinc for chemical toxicity and uranium and associated radionuclides for radiation. The conceptual exposure model identified ingestion, inhalation, absorption, and dietary transfer (bioaccumulation or bioconcentration) as critical contaminant exposure pathways. The biological survey of plants, invertebrates, amphibians, reptiles, birds, and small mammals is the first to document and provide ecological information on .200 species in and around the mine site; this study also provides critical baseline information about the local food web. Most of the species documented at the mine are common to ponderosa pine Pinus ponderosa and pinyon&ndash;juniper Pinus&ndash;Juniperus spp. forests in northern Arizona and are not considered to have special conservation status by state or federal agencies; exceptions are the locally endemic Tusayan flameflower Phemeranthus validulus, the long-legged bat Myotis volans, and the Arizona bat Myotis occultus. The most common vertebrate species identified at the mine site included the Mexican spadefoot toad Spea multiplicata, plateau fence lizard Sceloporus tristichus, violetgreen swallow Tachycineta thalassina, pygmy nuthatch Sitta pygmaea, purple martin Progne subis, western bluebird Sialia mexicana, deermouse Peromyscus maniculatus, valley pocket gopher Thomomys bottae, cliff chipmunk Tamias dorsalis, black-tailed jackrabbit Lepus californicus, mule deer Odocoileus hemionus, and elk Cervus canadensis. A limited number of the most common species were collected for contaminant analysis to establish baseline contaminant and radiological concentrations prior to ore extraction. These empirical baseline data will help validate contaminant exposure pathways and potential threats from contaminant exposures to ecological receptors. Resource managers will also be able to use these data to determine the extent to which local species are exposed to chemical and radiation contamination once the mine is operational and producing ore. More broadly, these data could inform resource management decisions on mitigating chemical and radiation exposure of biota at high-grade uranium breccia pipes throughout the Grand Canyon watershed.

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USGS2013

Qualilty, isotopes, and radiochemistry of water sampled from the Upper Moenkopi Village water-supply wells, Coconino County, Arizona

The Hopi Tribe Water Resources Program has granted contracts for studies to evaluate water supply conditions for the Moenkopi villages in Coconino County, Arizona. The Moenkopi villages include Upper Moenkopi Village and the village of Lower Moencopi, both on the Hopi Indian Reservation south of the Navajo community of Tuba City. These investigations have determined that water supplies are limited and vulnerable to several potential sources of contamination, including the Tuba City Landfill and a former uranium processing facility known as the Rare Metals Mill. Studies are ongoing to determine if uranium and other metals in groundwater beneath the landfill are greater than regional groundwater concentrations. The source of water supply for the Upper Moenkopi Village is three public-supply wells. The wells are referred to as MSW-1, MSW-2, and MSW-3 and all three wells obtain water from the regionally extensive N aquifer. The N aquifer is the principal aquifer in this region of northern Arizona and consists of thick beds of sandstone between less permeable layers of siltstone and mudstone. The relatively fine-grained character of the N aquifer inhibits rapid movement of water and large yields to wells. In recent years, water levels have declined in the three public-supply wells, causing concern that the current water supply will not be able to accommodate peak demand and allow for residential and economic growth. Analyses of major ions, nutrients, selected trace metals, stable and radioactive isotopes, and radiochemistry were performed on the groundwater samples from the three public-supply wells to describe general water-quality conditions and groundwater ages in and immediately surrounding the Upper Moenkopi Village area. None of the water samples collected from the public-supply wells exceeded the U.S. Environmental Protection Agency primary drinking water standards. The ratios of the major dissolved ions from the samples collected from MSW-1 and MSW-2 indicate water with a major ion composition of calcium and sulfate. There is no significant vertical distribution of ion concentrations in the samples collected from the upper and lower portion of the water column within the two wells. The samples collected at MSW-3 are higher in sodium and lower in calcium than the samples collected from MSW-1 and MSW-2, and contain a similar sulfate-ion percentage. There is a vertical distribution of ion concentrations in the samples collected from the upper and lower portion of the water column in MSW-3. Groundwater samples from the three water-supply wells analyzed for oxygen-18 and deuterium stable isotopes plot on a local water line that is approximately parallel to the global meteoric water line. Tritium concentrations in samples from MSW-1 and MSW-3 were equal to or less than laboratory detection limits and were interpreted to contain no modern (post-1952) water. Tritium concentration in a sample from the top of the water column at MSW-2 was 0.41 tritium units, indicating that the composition is primarily pre-bomb (pre-1952) water, but may contain a small fraction of post-bomb modern water. The calculated carbon-14 ages of groundwater in MSW-1 and MSW-2, both completed about 140 feet into the Navajo Sandstone, are about 3,000 years before present. The calculated carbon-14 age of groundwater in MSW-3, completed about 240 feet into the Kayenta Formation-Navajo Sandstone transition zone is about 5,000 years before present in the upper portion of the water column and about 8,500 years before present in the lower portion of the water column. The gross alpha radioactivity of samples collected from the three water-supply wells ranged from 5.1 to 9.8 picocuries per liter-less than the U.S. Environmental Protection Agency primary drinking water standard of 15 picocuries per liter. The gross beta radioactivity of samples collected from the wells ranged from 0.9 to 2.8 picocuries per liter and are not considered elevated relative to the U.S. Environmental Protection Agency primary drinking water standard.

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USGS2013

Geologic map of the Glen Canyon Dam 30’ x 60’ quadrangle, Coconino County, northern Arizona

The Glen Canyon Dam 30’ x 60’ quadrangle is characterized by nearly flat lying to gently dipping Paleozoic and Mesozoic sedimentary strata that overlie tilted Proterozoic strata or metasedimentary and igneous rocks similar to those exposed at the bottom of Grand Canyon southwest of the quadrangle. Mississippian to Permian rocks are exposed in the walls of Marble Canyon; Permian strata and minor outcrops of Triassic strata form the surface bedrock of House Rock Valley and Marble Plateau, southwestern quarter of the quadrangle. The Paleozoic strata exposed in Marble Canyon and Grand Canyon south of the map are likely present in the subsurface of the entire quadrangle but with unknown facies and thickness changes. The Mesozoic sedimentary rocks exposed along the Vermilion and Echo Cliffs once covered the entire quadrangle, but Cenozoic erosion has removed most of these rocks from House Rock Valley and Marble Plateau areas. Mesozoic strata remain over much of the northern and eastern portions of the quadrangle where resistant Jurassic sandstone units form prominent cliffs, escarpments, mesas, buttes, and much of the surface bedrock of the Paria, Kaibito, and Rainbow Plateaus. Jurassic rocks in the northeastern part of quadrangle are cut by a sub-Cretaceous regional unconformity that bevels the Entrada Sandstone and Morrison Formation from Cummings Mesa southward to White Mesa near Kaibito. Quaternary deposits, mainly eolian, mantle much of the Paria, Kaibito, and Rainbow Plateaus in the northern and northeastern portion of the quadrangle. Alluvial deposits are widely distributed over parts of House Rock Valley and Marble Plateau in the southwest quarter of the quadrangle. The east-dipping strata of the Echo Cliffs Monocline forms a general north-south structural boundary through the central part of the quadrangle, separating Marble and Paria Plateaus west of the monocline from the Kaibito Plateau east of the monocline. The Echo Cliffs Monocline continues north of the quadrangle into southern Utah. The gentle north- and northeast-dipping Mesozoic strata on the Kaibito and Rainbow Plateaus are partly interrupted by northwest-trending, broad-based, ill-defined synclines and anticlines. These broad-based structures form mesas and buttes near anticlinal crests and deeply incised drainages in synclinal valleys. The 1,300-ft-thick (396-m-thick) Navajo Sandstone erodes into a maze of tributary slot canyons in the northeastern part of the quadrangle. Mesozoic strata in the extreme northeast corner of the quadrangle dip gently southwest due to the influence of the Monument Upwarp in southeastern Utah and by an intrusive uplift (laccolith) that forms Navajo Mountain, a prominent 10,388 ft (3,166 m) landmark just northeast of the quadrangle.

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USGS2013

The innate immune response may be important for surviving plague in wild Gunnison's prairie dogs

Prairie dogs (Cynomys spp.) are highly susceptible to Yersinia pestis, with &ge;99% mortality reported from multiple studies of plague epizootics. A colony of Gunnison's prairie dogs (Cynomys gunnisoni) in the Aubrey Valley (AV) of northern Arizona appears to have survived several regional epizootics of plague, whereas nearby colonies have been severely affected by Y. pestis. To examine potential mechanisms accounting for survival in the AV colony, we conducted a laboratory Y. pestis challenge experiment on 60 wild-caught prairie dogs from AV and from a nearby, large colony with frequent past outbreaks of plague, Espee (n = 30 per colony). Test animals were challenged subcutaneously with the fully virulent Y. pestis strain CO92 at three doses: 50, 5,000, and 50,000 colony-forming units (cfu); this range is lethal in black-tailed prairie dogs (Cynomys ludovicianus). Contrary to our expectations, only 40% of the animals died. Although mortality trended higher in the Espee colony (50%) compared with AV (30%), the differences among infectious doses were not statistically significant. Only 39% of the survivors developed moderate to high antibody levels to Y. pestis, indicating that mechanisms other than humoral immunity are important in resistance to plague. The ratio of neutrophils to lymphocytes was not correlated with plague survival in this study. However, several immune proteins with roles in innate immunity (VCAM-1, CXCL-1, and vWF) were upregulated during plague infection and warrant further inquiry into their role for protection against this disease. These results suggest plague resistance exists in wild populations of the Gunnison's prairie dog and provide important directions for future studies.

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USGS2012

Depth of cinder deposits and water-storage capacity at Cinder Lake, Coconino County, Arizona

The 2010 Schultz fire northeast of Flagstaff, Arizona, burned more than 15,000 acres on the east side of San Francisco Mountain from June 20 to July 3. As a result, several drainages in the burn area are now more susceptible to increased frequency and volume of runoff, and downstream areas are more susceptible to flooding. Resultant flooding in areas downgradient of the burn has resulted in extensive damage to private lands and residences, municipal water lines, and roads. Coconino County, which encompasses Flagstaff, has responded by deepening and expanding a system of roadside ditches to move flood water away from communities and into an area of open U.S. Forest Service lands, known as Cinder Lake, where rapid infiltration can occur. Water that has been recently channeled into the Cinder Lake area has infiltrated into the volcanic cinders and could eventually migrate to the deep regional groundwater-flow system that underlies the area. How much water can potentially be diverted into Cinder Lake is unknown, and Coconino County is interested in determining how much storage is available. The U.S. Geological Survey conducted geophysical surveys and drilled four boreholes to determine the depth of the cinder beds and their potential for water storage capacity. Results from the geophysical surveys and boreholes indicate that interbedded cinders and alluvial deposits are underlain by basalt at about 30 feet below land surface. An average total porosity for the upper 30 feet of deposits was calculated at 43 percent for an area of 300 acres surrounding the boreholes, which yields a total potential subsurface storage for Cinder Lake of about 4,000 acre-feet. Ongoing monitoring of storage change in the Cinder Lake area was initiated using a network of gravity stations.

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USGS2012

Geologic map of the Tuba City 30' x 60' quadrangle, Coconino County, northern Arizona

The Tuba City 30’ x 60’ quadrangle encompasses approximately 5,018 km² (1,920 mi²) within Coconino County, northern Arizona. It is characterized by nearly flat lying to gently dipping sequences of Paleozoic and Mesozoic strata that overly tilted Precambrian strata or metasedimentary and igneous rocks that are exposed at the bottom of Grand Canyon. The Paleozoic rock sequences from Cambrian to Permian age are exposed in the walls of Grand Canyon, Marble Canyon, and Little Colorado River Gorge. Mesozoic sedimentary rocks are exposed in the eastern half of the quadrangle where resistant sandstone units form cliffs, escarpments, mesas, and local plateaus. A few Miocene volcanic dikes intrude Mesozoic rocks southwest, northwest, and northeast of Tuba City, and Pleistocene volcanic rocks representing the northernmost extent of the San Francisco Volcanic Field are present at the south-central edge of the quadrangle. Quaternary deposits mantle much of the Mesozoic rocks in the eastern half of the quadrangle and are sparsely scattered in the western half. Principal folds are the north-south-trending, east-dipping Echo Cliffs Monocline and the East Kaibab Monocline. The East Kaibab Monocline elevates the Kaibab, Walhalla, and Coconino Plateaus and parts of Grand Canyon. Grand Canyon erosion has exposed the Butte Fault beneath the east Kaibab Monocline, providing a window into the structural complexity of monoclines in this part of the Colorado Plateau. Rocks of Permian and Triassic age form the surface bedrock of Marble Plateau and House Rock Valley between the East Kaibab and Echo Cliffs Monoclines. The Echo Cliffs Monocline forms a structural boundary between the Marble Plateau to the west and the Kaibito and Moenkopi Plateaus to the east. Jurassic rocks of the Kaibito and Moenkopi Plateaus are largely mantled by extensive eolian sand deposits. A small part of the northeast-dipping Red Lake Monocline is present in the northeast corner of the quadrangle. A broad and gentle elongated anticline, the Limestone Ridge Anticline, forms the crest of Marble Plateau. Here, Paleozoic and Mesozoic strata generally dip less than 1° to 2° in all directions from a central high area along Limestone Ridge north of Bodaway Mesa and east of Cedar Ridge and The Gap. The Limestone Ridge Anticline plunges gently southeast toward the Painted Desert at the south edge of the quadrangle and northward toward Lees Ferry, Arizona, at the north-central edge of the quadrangle. The Tuba City Syncline is a very broad northwest-southeast-oriented-synclinal downwarp that parallels the Echo Cliffs Monocline north of Tuba City. The Preston Mesa Anticline is a small fold present on Kaibito Plateau north of Tuba City.

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USGS2007

Geologic map of the Cameron 30' x 60' quadrangle, Coconino County, northern Arizona

This geologic map is the result of a cooperative effort of the U.S. Geological Survey and the National Park Service in collaboration with the Navajo Nation and the Hopi Tribe to provide regional geologic information for resource management officials of the National Park Service, U.S. Forest Service, Navajo Indian Reservation (herein the Navajo Nation), the Hopi Tribe, and for visitor information services at Grand Canyon National Park, Arizona as well as private enterprises that have lands within the area. The Cameron 30’ x 60’ quadrangle encompasses approximately 5,018 km 2 (1,960 mi 2 ) within Coconino County, northern Arizona and is bounded by longitude 111° to 112° W., and latitude 35°30’ to 36° N. The map area is within the southern Colorado Plateaus geologic province (herein Colorado Plateau). The map area is locally subdivided into six physiographic areas: the Grand Canyon (including the Little Colorado River Gorge), Coconino Plateau, Marble Plateau, Little Colorado River Valley, Moenkopi Plateau, and the San Francisco Volcanic Field as defined by Billingsley and others, 1997 (fig. 1). Elevations range from about 2,274 m (7,460 ft) at the south rim of Grand Canyon along State Highway 64 to about 994 m (3,260 ft) in the Grand Canyon, northeast quarter of the map area. The Cameron quadrangle is one of the few remaining areas near the Grand Canyon where uniform geologic mapping was needed for geologic connectivity of the regional geologic framework that will be useful to federal, state, and private land resource managers who direct environmental and land management programs such as range management, biological studies, flood control, and water resource investigations. The geologic information presented will support future and ongoing local geologic investigations and associated scientific studies of all disciplines within the Cameron quadrangle area.

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USGS1979

Map showing ground-water conditions in the Bodaway Mesa area, Coconino County, Arizona: 1977

The Bodaway Mesa area includes about 800 square miles in north-central Arizona, and most of the area is in the Navajo Indian Reservation. Ground-water development has been slight; in 1977 the estimated ground-water withdrawal was less than 5 acre-feet. The Chinle Formation is the principal aquifer tapped by wells, and in places the Moenkopi Formation and the Redwall and Muav Limestones yield water to wells and springs. Water levels in the Chinle Formation are 15 to 200 feet below the land surface. The water from one well completed in the Petrified Forest Member of the Chinle Formation contained 1,210 milligrams per liter of dissolved solids; the dissolved-solids concentrations from two wells in the Shinarump Member of the Chinle were 1,000 and 1,110 milligrams per liter. Three wells penetrate the Moenkopi Formation, but only one yields water. One well obtains its water from the Redwall Limestone, and the water level is 2,200 feet below the land surface. About 60 cubic feet per second of water is discharged by springs that issue from the Redwall and Muav Limestones along the east wall of the canyon of the Little Colorado River. Information on the map includes depth to water, altitude of the water level, specific conductance, and fluoride concentrations. Scale 1:125,000.

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USGS1979

Stratigraphic sections of Jurassic San Rafael Group and adjacent rocks in Coconino County, Arizona

These sections were measured prior to 1960, before adoption of the metric system. Publication was delayed by other assignments of the authors and later by the untimely death of J. C. Wright. They are being released at this time because of the increased interest in the uranium potential of Jurassic rocks. The Summerville, Entrada, and Carmel are the only formations of the San Rafael Group that are present in these sections.

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USGS1978

Map showing ground-water conditions in the House Rock area, Coconino County, Arizona-- 1976

The House Rock area includes about 1,500 sq mi in north-central Arizona. Ground water is present in several aquifers that are made up of one or more formations. In the Paria Plateau and Wahweap areas ground water is obtained from the N aquifer, which includes the Navajo Sandstone, Kayenta Formation, and Moenave Formation. Reported static water levels in wells range from 515 to 1,500 ft below the land surface. The chemical quality of the water in the N aquifer varies with location, and dissolved solids generally are less than 850 milligrams per liter. Several wells and test holes in the Lees Ferry area penetrate either the alluvium, Chinle Formation, Moenkopi Formation, or a combination of these. As of 1976, water from these wells was not being used because of poor chemical quality. In the southern and western parts of the area many springs discharge from te Kaibab, Redwall , and Muav Limestones. The quality of water from these formations generally is excellent. Information on the map (scale 1:125,000) includes the principal aquifer that furnishes water to individual wells and springs, depth to water, altitude of the water level, and chemical quality of the water. (Woodard-USGS)

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