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USGS1905

Twenty-Sixth Annual Report of the Director of the United States Geological Survey, 1904-1905

Introduction Remarks on the work of the year Branches of work The United States Geological Survey was created in 1879 for the purpose—as its name implies—of examining and reporting on the geologic structure and mineral resources and products of the national domain. To the adequate description of geologic formations and structure cartography is essential, and Congress early recognized this fact by making appropriations for the preparation of a geologic map of the United States. The topographic base map, in order to show with sufficient precision the relations of the geologic formations and the intricacies of the structure, must have a rather large scale and present considerable detail. No such map of this country existed in 1879, and its preparation was immediately begun. The waters of the country are of vast importance, and in a broad sense may be regarded as one of its greatest mineral resources. Hence, in the evolution of the work of the Survey, and especially in view of the great importance of the subject to the irrigation interests, Congress early began making appropriations for ascertaining the amount and quality of the surface and underground waters and when, in 1902, the service for the reclamation of arid lands was organized, that work naturally was placed in the hands of the Secretary of the Interior and by him intrusted to the Director of the Survey. The three great branches of work carried on by the Geological Survey are, therefore, the geologic, the topographic, and the hydrographic, and with these, more especially the latter, is conjoined the Reclamation Service ; publication and administration constitute necessary auxiliary branches. Along these great lines the work of the Survey has progressed without essential variation for many years. The changes made have been due to normal expansion rather than to radical departure in object or plan. State cooperation During the last fiscal year, State cooperation, as explained in previous reports, continued. Arrangements for cooperation in geologic work were made with five States, the total amount contributed by them being about \$8,000, and arrangements for cooperative topographic surveys were made with eleven States, the amount available for such surveys being thus increased by more than \$100,000. Reclamation service The work of the Reclamation Service during the last fiscal year was advanced as rapidly as was thought consistent with thoroughness and accuracy. Actual construction is now in progress on eight projects, as follows : Salt River, Arizona; Truckee-Carson, Nevada; Hondo, New Mexico ; Uncompahgre Valley, Colorado; Minidoka, Idaho; Belle Fourche, South Dakota ; North Platte, Wyoming and Nebraska ; and Shoshone, Wyoming. Proposals were received for work on the Laguna dam, Yuma project, California and Arizona; Huntley project, Montana, and the Fort Buford project, North Dakota and Montana. In several other States operations are at a point where advertisements for bids only await the removal of certain legal obstacles, the settlement of international difficulties, or the termination of delays on the part of local organizations or individuals. The organization of the body of men constituting the personnel of the Reclamation Service, whose field of operations covers so large a territory, though necessarily difficult, has been satisfactorily accomplished, and precedents have been established along approved lines. The general allotment of funds has been made with a view to the greatest benefit to the greatest number, and from the broad standpoint of the welfare of the country as a whole. One of the important features in the evolution of the irrigation work is the development of power, which the numerous dams and, drops in canals make possible. Plans were made to transmit the power being developed in many sections of the arid regions, by means of electricity, to points more or less distant, there to be used for raising underground waters, pumping waters lying above the line of gravity canals, or for various other purposes, and attention was also given to the character of the soils and of the water to be used upon them, the materials used in the construction of the works, and numerous other details incident to reclamation by irrigation. Coal-testing plant Under two special appropriations of \$30,000 each, carried by the urgent deficiency bill approved February 18, 1904, and the general deficiency bill approved April 27, 1904, the Director of the Geological Survey was authorized to construct and operate at the Louisiana Purchase Exposition a plant for testing the coals and lignites of the United States, in order to determine their fuel values and the most economic method of their utilization for different purposes, it being provided that all testing machinery and all coals and lignites to be tested 'should be contributed free of charge to the Government. For carrying out the provisions of these acts the Director appointed a committee, consisting of Edward W. Parker, Joseph A. Holmes, and Marius R. Campbell, to direct the construction and operation of the plant. This committee received the heartiest cooperation from the manufacturers of such equipment as was needed for the installation of the plant, from the railroad companies in freight concessions and transportation for the experts and their assistants, and from the coal operators in the furnishing of coal in carload lots for testing purposes. Although the utmost expedition was used in the construction of the plant, it was not until the first of September that the testing work actually began. Between the first of September and the close of the exposition 65 carload samples of coal for testing purposes were received, and the results of the investigation were published in a preliminary report issued as Geological Survey Bulletin No. 261. The coals tested were received from 17 States and Territories, and much valuable information regarding the best uses to which the different coals may be put was obtained. One of the most important facts developed during this investigation is the possibility of utilizing the vast lignite resources of the West in the manufacture of producer gas, it having been shown that a higher grade of this gas can be obtained from lignite than from ordinary bituminous and anthracite coal. The investigation also showed that the slack or fine coal produced at the dry, noncoking bituminous coal mines of the middle West, large quantities of which are now being wasted, can be profitably utilized by briquetting.

Annual Report↗
USGS2002

Geologic map of the Frisco quadrangle, Summit County, Colorado

New 1:24,000-scale geologic mapping along the Interstate-70 urban corridor in western Colorado, in support of the USGS Central Region State/USGS Cooperative Geologic Mapping Project, is contributing to a more complete understanding of the stratigraphy, structure, tectonic evolution, and hazard potential of this rapidly developing region. The 1:24,000-scale Frisco quadrangle is near the headwaters of the Blue River and straddles features of the Blue River graben (Kellogg, K.S., 1999, Neogene basins of the northern Rio Grande rift?partitioning and asymmetry inherited from Laramide and older uplifts: Tectonophysics, v. 305, p. 141-152.), part of the northernmost reaches of the Rio Grande rift, a major late Oligocene to recent zone of extension that extends from Colorado to Mexico. The Williams Range thrust fault, the western structural margin of the Colorado Front Range, cuts the northeastern corner of the quadrangle. The oldest rocks in the quadrangle underlie the Tenmile Range and include biotite-sillimanite schist and gneiss, amphibolite, and migmatite that are intruded by granite inferred to be part of the 1,667-1,750 Ma Routt Plutonic Suite (Tweto, Ogden, 1987, Rock units of the Precambrian- basement in Colorado: U.S. Geological Survey Professional Paper 1321-A, 54 p.). The oldest sedimentary unit is the Pennsylvanian Maroon Formation, a sequence of red sandstone, conglomerate, and interbedded shale. The thickest sequence of sedimentary rocks is Cretaceous in age and includes at least 500 m of the Upper Cretaceous Pierre Shale. The sedimentary rocks are intruded by sills and dikes of dacite porphyry sills of Swan Mountain, dated at 44 Ma (Marvin, R.F., Mehnert, H.H., Naeser, C.W., and Zartman, R.E., 1989, U.S. Geological Survey radiometric ages, compilation ?C??Part five?Colorado, Montana, Utah, and Wyoming: Isochron/West, no. 53, p. 14-19. Simmons, E.C., and Hedge, C.E., 1978, Minor-element and Sr-isotope geochemistry of Tertiary stocks, Colorado mineral belt: Contributions to Mineralogy and Petrology, v. 67, p. 379-396.). Surficial deposits include (1) an old, deeply dissected landslide deposit, possibly as old as Tertiary, on the south flank of Tenderfoot Mountain, (2) deeply weathered, very coarse gravel deposits, mostly along Gold Run and underlying Mesa Cortina; the gravels are gold bearing and were mined by hydraulic methods in the 1800's, (3) glacial deposits of both Bull Lake (middle Pleistocene) and Pinedale (late Pleistocene) that were derived from large valley glaciers that flowed down Tenmile and North Tenmile Creeks; the town of Frisco is underlain mostly by Pinedale-age glacial outwash, (4) recent landslide deposits, including one large (about 1 square kilometer) area just downslope from Lilly Pad Lake, west of I-70, and (5)extensive colluvial and alluvial deposits. The latest seismic events appear to be middle Pliestocene in age and are associated with small scarps that cut Bull Lake till but do not cut Pinedale till.

Miscellaneous Field Studies Map↗
USGS2003

Geologic map of the Vail East quadrangle, Eagle County, Colorado

New 1:24,000-scale geologic mapping along the Interstate-70 urban corridor in western Colorado, in support of the State/USGS Cooperative Geologic Mapping Project, is contributing to a more complete understanding of the stratigraphy, structure, tectonic evolution, and hazard potential of this rapidly developing region. The 1:24,000-scale Vail East quadrangle straddles the Gore fault system, the western structural boundary of the Gore Range. The Gore fault system is a contractional structure that has been recurrently active since at least the early Paleozoic and marks the approximate eastern boundary of the Central Colorado trough, a thick late Paleozoic depocenter into which thousands of meters of clastic sediment were deposited from several uplifts, including the ancestral Front Range. The Gore fault was active during both the late Paleozoic and Upper Cretaceous-lower Tertiary (Laramide) deformations. In addition, numerous north-northwest faults that cut the crystalline rocks of the Gore Range were active during at least 5 periods, the last of which was related to Neogene uplift of the Gore Range and formation of the northern Rio Grande rift. Early Proterozoic crystalline rocks underlie the high Gore Range, north and east of the Gore fault system. These rocks consist predominantly of migmatitic biotite gneiss intruded by mostly granitic rocks of the 1.667-1.750 Ma Cross Creek batholith, part of the 1,667-1,750 Ma Routt Plutonic Suite (Tweto, 1987). Southwest of the Gore fault, a mostly gently south-dipping sequence of Pennsylvanian Mimturn Formation, as thick as 1,900 m, and the Permian and Pennsylvanian Maroon Formation (only the basal several hundred meters are exposed in the quadrangle)were shed from the ancestral Front Range and overlie a thin sequence of Devonian and Cambrian rocks. The Minturn Formation is a sequence of interlayered pink, maroon, and gray conglomerate, sandstone, shale, and marine limestone. The Maroon Formation is mostly reddish conglomerate and sandstone. Glacial till of both the middle Pleistocene Bull Lake and late Pleistocene Pinedale glaciations are well exposed along parts of the Gore Creek valley and its tributaries, although human development has profoundly altered the outcrop patterns along the Gore Creek valley bottom. Landslides, some of which are currently active, are also mapped.

Miscellaneous Field Studies Map↗
USGS2002

Geologic map of the Dillon quadrangle, Summit and Grand Counties, Colorado

New 1:24,000-scale geologic mapping along the Interstate-70 urban corridor in western Colorado, in support of the USGS Central Region State/USGS Cooperative Geologic Mapping Project, is contributing to a more complete understanding of the stratigraphy, structure, tectonic evolution, and hazard potential of this rapidly developing region. The 1:24,000-scale Dillon quadrangle is near the headwaters of the Blue River and straddles features of the Blue River graben (Kellogg, 1999), part of the northernmost reaches of the Rio Grande rift, a major late Oligocene to recent zone of extension that extends from Colorado to Mexico. The Williams Range thrust fault, the western structural margin of the Colorado Front Range, cuts through the center of the quadrangle, although is mostly covered by surficial deposits. The oldest rocks in the quadrangle underlie the Williams Fork Mountains and the ridge immediately east of South Fork Middle Fork River, and include biotite-sillimanite schist and gneiss, amphibolite, and migmatite that are intruded by granite inferred to be part of the 1,667-1,750 Ma Routt Plutonic Suite (Tweto, 1987). The oldest exposed sedimentary unit is the Upper Jurassic Morrison Formation, but Pennsylvanian Maroon Formation, a sequence of red sandstone, conglomerate, and interbedded shale, underlies the southern part of the quadrangle. The thickest sequence of sedimentary rocks is Cretaceous in age and includes at least 500 m of the Upper Cretaceous Pierre Shale. Surficial deposits include (1) an old, deeply dissected landslide deposit, possibly as old as Pliocene, on the west flank of the Williams Fork Mountains, (2) deeply weathered, very coarse gravel deposits underlying a mesa in the southwest part of the quadrangle (the Mesa Cortina subdivision. The gravels are gold bearing and were mined by hydraulic methods in the 1800s), (3) moderately to deeply weathered, widespread, bouldery material that is a combination of till of the Bull Lake glaciation, debris-flow deposits, landslide deposits, and possibly pre-Bull Lake till, (4) glacial deposits of both Bull Lake (middle Pleistocene) and Pinedale (late Pleistocene)glaciations, (5) recent landslide deposits, and (6)extensive colluvial and alluvial deposits.

Miscellaneous Field Studies Map↗
USGS2020

Forecasting future beach width- A case study along the Florida Atlantic coast

Historical cross-shore positions of the shoreline and dune base were used as inputs for a Kalman filter algorithm to forecast the positions of these features in the year 2028. The beach width was also computed as the cross-shore distance between the forecasted 2028 shoreline and dune-base positions. While it does not evaluate the suitability of a nesting beach or identify optimal nesting habitat, the beach width can be used as a proxy for habitat availability. An analysis was conducted along the Florida Atlantic coast with an initial goal of demonstrating a method that combines available data for shoreline and dune positions with a Kalman Filter algorithm developed to predict decadal-scale shoreline evolution and then uses these features to define future beach width. This section of the southeastern United States hosts the largest assemblage of nesting loggerhead sea turtles ( Caretta caretta ) in the world, in addition to other species, and critical habitat is designated as part of the species’ listing package under the Endangered Species Act of 1973 (16 U.S.C. ch. 35 § 1531 et seq) for most of the nesting beaches within the study area. This work introduces an approach to inform ecosystem services assessments using data typically derived for shoreline change and storm vulnerability models.

Florida↗
USGS1979

Uranium, thorium, and mercury distribution through the evolution of the McDermitt Caldera complex

The McDermitt caldera complex developed over a period of 5 m.y. years during which ash-flow tuff sheets anomalous in mercury, uranium, and thorium were emplaced. The moat portions of the caldera complex were subsequently filled with tuffaceous sediments. Late in the caldera development near-surface intrusives and domes were emplaced along the margins of the complex and mineralized with uranium. Seven large hydrothermal systems developed at this time and formed large areas of alteration within the caldera-fill volcanics and sediments. Five of the altered zones are associated with economic concentrations of uranium, and or mercury.

Nevada, Oregon↗
USGS1997

Geologic map of the Dillon quadrangle, Summit and Grand Counties, Colorado

New 1:24,000-scale geologic mapping along the Interstate-70 urban corridor in western Colorado, in support of the USGS Central Region State/USGS Cooperative Geologic Mapping Project, is contributing to a more complete understanding of the stratigraphy, structure, tectonic evolution, and hazard potential of this rapidly developing region. The 1:24,000-scale Dillon quadrangle is near the headwaters of the Blue River and straddles features of the Blue River graben (Kellogg, 1999), part of the northernmost reaches of the Rio Grande rift, a major late Oligocene to recent zone of extension that extends from Colorado to Mexico. The Williams Range thrust fault, the western structural margin of the Colorado Front Range, cuts through the center of the quadrangle, although is mostly covered by surficial deposits. The oldest rocks in the quadrangle underlie the Williams Fork Mountains and the ridge immediately east of South Fork Middle Fork River, and include biotite-sillimanite schist and gneiss, amphibolite, and migmatite that are intruded by granite inferred to be part of the 1,667-1,750 Ma Routt Plutonic Suite (Tweto, 1987). The oldest exposed sedimentary unit is the Upper Jurassic Morrison Formation, but Pennsylvanian Maroon Formation, a sequence of red sandstone, conglomerate, and interbedded shale, underlies the southern part of the quadrangle. The thickest sequence of sedimentary rocks is Cretaceous in age and includes at least 500 m of the Upper Cretaceous Pierre Shale. Surficial deposits include (1) an old, deeply dissected landslide deposit, possibly as old as Pliocene, on the west flank of the Williams Fork Mountains, (2) deeply weathered, very coarse gravel deposits underlying a mesa in the southwest part of the quadrangle (the Mesa Cortina subdivision. The gravels are gold bearing and were mined by hydraulic methods in the 1800s), (3) moderately to deeply weathered, widespread, bouldery material that is a combination of till of the Bull Lake glaciation, debris-flow deposits, landslide deposits, and possibly pre-Bull Lake till, (4) glacial deposits of both Bull Lake (middle Pleistocene) and Pinedale (late Pleistocene)glaciations, (5) recent landslide deposits, and (6)extensive colluvial and alluvial deposits.

Colorado↗
USGS2018

Ecological drought: Accounting for the non-human impacts of water shortage in the Upper Missouri Headwaters Basin, Montana, USA

Water laws and drought plans are used to prioritize and allocate scarce water resources. Both have historically been human-centric, failing to account for non-human water needs. In this paper, we examine the development of instream flow legislation and the evolution of drought planning to highlight the growing concern for the non-human impacts of water scarcity. Utilizing a new framework for ecological drought, we analyzed five watershed-scale drought plans in southwestern Montana, USA to understand if, and how, the ecological impacts of drought are currently being assessed. We found that while these plans do account for some ecological impacts, it is primarily through the narrow lens of impacts to fish as measured by water temperature and streamflow. The latter is typically based on the same ecological principles used to determine instream flow requirements. We also found that other resource plans in the same watersheds (e.g., Watershed Restoration Plans, Bureau of Land Management (BLM) Watershed Assessments or United States Forest Service (USFS) Forest Plans) identify a broader range of ecological drought risks. Given limited resources and the potential for mutual benefits and synergies, we suggest greater integration between various planning processes could result in a more holistic consideration of water needs and uses across the landscape.

Montana↗
USGS2007

Optimization of an ecosystem model through the assimilation of eddy flux observations using a smoothed ensemble Kalman filter

The parameters of ecosystem models are conventionally optimized through nonsequential inversion methods, which treat observations as a whole and lack the flexibility to investigate possible temporal evolution of the model parameters. This research developed a smoothed ensemble Kalman filter (SEnKF) to assess to what extent the parameters and state variables of an ecosystem model can be simultaneously optimized through the assimilation of eddy flux observations. The performance of the SEnKF was demonstrated in one case study: the assimilation of measurements of carbon exchange between a mixed forest and the atmosphere at Niwot Ridge Forest (Colorado, USA) from 2000 to 2004 into a carbon flux partition model. Our analyses demonstrated that some model parameters, such as light use efficiency and respiration coefficients, were highly constrained by eddy flux data at daily to seasonal time scales. Light use efficiency was strongly seasonal. Model predictions based on parameters modified by the SEnKF were much improved, compared to predictions made without progressive data assimilation. The SEnKF reduced the variance of state variables that is caused by uncertainties of parameters and driving variables. The analysis of net ecosystem exchange of carbon between the forest and the atmosphere was improved.

Conference Paper↗
USGS1991

Geochemistry of ground water in alluvial basins of Arizona and adjacent parts of Nevada, New Mexico, and California

Chemical and isotope analyses of ground water from 28 basins in the Basin and Range physiographic province of Arizona and parts of adjacent States were used to evaluate ground-water quality, determine processes that control ground-water chemistry, provide independent insight into the hydrologic flow system, and develop information transfer. The area is characterized by north- to northwest-trending mountains separated by alluvial basins that form a regional topography of alternating mountains and valleys. On the basis of ground-water divides or zones of minimal basin interconnection, the area was divided into 72 basins, each representing an individual aquifer system. These systems are joined in a dendritic pattern and collectively constitute the major water resource in the region. Geochemical models were developed to identify reactions and mass transfer responsible for the chemical evolution of the ground water. On the basis of mineralogy and chemistry of the two major rock associations of the area, a felsic model and a mafic model were developed to illustrate geologic, climatic, and physiographic effects on ground-water chemistry. Two distinct hydrochemical processes were identified: (1) reactions of meteoric water with minerals and gases in recharge areas and (2) reactions of ground water as it moves down the hydraulic gradient. Reactions occurring in recharge and downgradient areas can be described by a 13-component system. Major reactions are the dissolution and precipitation of calcite and dolomite, the weathering of feldspars and ferromagnesian minerals, the formation of montmorillonite, iron oxyhydroxides, and probably silica, and, in some basins, ion exchange. The geochemical modeling demonstrated that relatively few phases are required to derive the ground-water chemistry; 14 phases-12 mineral and 2 gas-consistently account for the chemical evolution in each basin. The final phases were selected through analysis of X-ray diffraction and fluorescence data, aqueous speciation and saturation data, and mass-balance and isotopic constraints and through chemical models developed from mineral combinations among the 27 phases that were considered realistic in these geologically and mineralogically complex basins. X-ray diffraction of basin-fill sediments confirm the presence of the postulated minerals and their weathering sequences. High partial pressures of soil CO2 and large concentrations of dissolved CO2 in recharge areas, and the rapid depletion of CO2 downgradient, accompanied by high weathering rates of the silicates which also decrease downgradient, indicate that carbonic acid is the impetus in the weathering process. Reactions in the soil zone and the unsaturated zone are influential and, in some instances, are as important as the mineralogy of the source rock in determining ground-water compositions. The basins can be divided geochemically into two general categories-closed systems, which evolve under closed hydrologic conditions, and open systems, which are open to CO2 and other constituents along the flow path. The ground-water chemistry of the unconfined aquifers in the eastern part of the study area and of the aquifers underlying the flood plain along the Colorado River generally evolves under open conditions. The ground-water chemistry of most basins in the central and western parts and of the confined aquifers in the eastern part evolves under closed conditions. The factors that determine whether a basin is an open or closed system are the amount of and the spatial and seasonal distribution of annual precipitation and the presence or absence of fine-grained confining units. The basins along the Colorado River are unique among basins in the region. Virtually all ground water underlying the flood plain originated as seepage or overbank flow from the Colorado River. Initial deuterium content of about -120 per mil is indicative of precipitation from the central part of Colorado. Using chemical m

Professional Paper↗
USGS2019

A parametric numerical analysis of factors controlling ground ruptures caused by groundwater pumping

A modeling analysis is used to investigate the relative susceptibility of various hydrogeologic configurations to aseismic rupture generation due to deformation of aquifer systems accompanying groundwater pumping. An advanced numerical model (GEPS3D) is used to simulate rupture generation and propagation for three typical processes: (i) reactivation of a preexisting fault, (ii) differential compaction due to variations in thickness of aquifer/aquitard layers constituting the aquifer system, and (iii) tensile fracturing above a bedrock ridge that forms the base of the aquifer system. A sensitivity analysis is developed to address the relative importance of various factors, including aquifer depletion, aquifer thickness, the possible uneven distribution and depth below land surface of the aquifer/aquitard layers susceptible to aquifer-system compaction, and the height of bedrock ridges beneath the aquifer system which contributes to thinning of the aquifer system. The rupture evolution is classified in two occurrences. In one, the rupture develops at the top of the aquifer or at land surface and does not propagate. In the other, the developed rupture propagates from the aquifer top toward the land surface and/or from the land surface downward. The aquifer depth is the most important factor controlling rupture evolution. Specifically, the probability of a significant rupture propagation is higher when the aquifer top is near land surface. The numerical results are processed by a statistical regression analysis to provide a general methodology for a preliminary evaluation of possible ruptures development in exploited aquifer systems susceptible to aquifer-system compaction and accompanying land subsidence. A comparison with a few representative case studies in Arizona, USA, China, and Mexico supports the study outcomes.

Arizona↗
USGS2008

An improved state-parameter analysis of ecosystem models using data assimilation

Much of the effort spent in developing data assimilation methods for carbon dynamics analysis has focused on estimating optimal values for either model parameters or state variables. The main weakness of estimating parameter values alone (i.e., without considering state variables) is that all errors from input, output, and model structure are attributed to model parameter uncertainties. On the other hand, the accuracy of estimating state variables may be lowered if the temporal evolution of parameter values is not incorporated. This research develops a smoothed ensemble Kalman filter (SEnKF) by combining ensemble Kalman filter with kernel smoothing technique. SEnKF has following characteristics: (1) to estimate simultaneously the model states and parameters through concatenating unknown parameters and state variables into a joint state vector; (2) to mitigate dramatic, sudden changes of parameter values in parameter sampling and parameter evolution process, and control narrowing of parameter variance which results in filter divergence through adjusting smoothing factor in kernel smoothing algorithm; (3) to assimilate recursively data into the model and thus detect possible time variation of parameters; and (4) to address properly various sources of uncertainties stemming from input, output and parameter uncertainties. The SEnKF is tested by assimilating observed fluxes of carbon dioxide and environmental driving factor data from an AmeriFlux forest station located near Howland, Maine, USA, into a partition eddy flux model. Our analysis demonstrates that model parameters, such as light use efficiency, respiration coefficients, minimum and optimum temperatures for photosynthetic activity, and others, are highly constrained by eddy flux data at daily-to-seasonal time scales. The SEnKF stabilizes parameter values quickly regardless of the initial values of the parameters. Potential ecosystem light use efficiency demonstrates a strong seasonality. Results show that the simultaneous parameter estimation procedure significantly improves model predictions. Results also show that the SEnKF can dramatically reduce the variance in state variables stemming from the uncertainty of parameters and driving variables. The SEnKF is a robust and effective algorithm in evaluating and developing ecosystem models and in improving the understanding and quantification of carbon cycle parameters and processes. ?? 2008 Elsevier B.V.

Ecological Modelling↗
USGS2020

Machine learning predictions of pH in the Glacial Aquifer System, Northern USA

A boosted regression tree model was developed to predict pH conditions in three dimensions throughout the glacial aquifer system of the contiguous United States using pH measurements in samples from 18,386 wells and predictor variables that represent aspects of the hydrogeologic setting. Model results indicate that the carbonate content of soils and aquifer materials strongly controls pH and, when coupled with long flowpaths, results in the most alkaline conditions. Conversely, in areas where glacial sediments are thin and carbonate‐poor, pH conditions remain acidic. At depths typical of drinking‐water supplies, predicted pH >7.5—which is associated with arsenic mobilization—occurs more frequently than predicted pH <6—which is associated with water corrosivity and the mobilization of other trace elements. A novel aspect of this model was the inclusion of numerically based estimates of groundwater flow characteristics (age and flowpath length) as predictor variables. The sensitivity of pH predictions to these variables was consistent with hydrologic understanding of groundwater flow systems and the geochemical evolution of groundwater quality. The model was not developed to provide precise estimates of pH at any given location. Rather, it can be used to more generally identify areas where contaminants may be mobilized into groundwater and where corrosivity issues may be of concern to prioritize areas for future groundwater monitoring.

Groundwater↗
USGS2019

Offset channels may not accurately record strike-slip fault displacement: Evidence from landscape evolution models

Slip distribution, slip rate, and slip per event for strike‐slip faults are commonly determined by correlating offset stream channels—under the assumption that they record seismic slip—but offset channels are formed by the interplay of tectonic and geomorphic processes. To constrain offset channel development under known tectonic and geomorphic conditions, we use numerical landscape evolution simulations along a theoretical strike‐slip fault with uniform and steady uplift, erosion, and diffusion. We investigate the influence of four tectonic parameters (fault zone width, earthquake recurrence interval, variance of the recurrence interval, and total slip relative to channel spacing) on offset channel development through multiple earthquake cycles. Analysis of >3,000 automatically measured offsets from >135 simulations suggests ~30% variability in individual measurements, but modeled displacement is recovered by averaging multiple measurements. However, the average of multiple offset measurements systematically underestimates modeled slip except when the fault zone is less than ~5 m wide, total slip is less than channel spacing, and offsets are measured shortly after an earthquake. In these simulations, postearthquake landscape evolution widens the geomorphic expression of the fault zone and modifies apparent channel offsets. We distinguish this “geomorphic fault zone” from the tectonic fault zone (zone of coseismic distributed deformation). This study highlights the capability of landscape evolution models to explore a range of conditions not easily defined in natural examples and the importance of averaging multiple measurements. Our results verify that paleoseismic studies must consider how geomorphic change has modified offset markers and use caution interpreting slip histories with multiple earthquakes.

Journal of Geophysical Research Solid Earth↗
USGS1983

Paleoceanographic implications of Miocene deep-sea hiatuses

Miocene paleoceanographic evolution exhibits major changes resulting from the opening and closing of passages, the subsequent changes in oceanic circulation, and development of major Antarctic glaciation. The consequences and timing of these events can be observed in variations in the distribution of deep-sea hiatuses, sedimentation patterns, and biogeographic distribution of planktic organisms. The opening of the Drake Passage in the latest Oligocene to early Miocene (25–20 Ma) resulted in the establishment of the deep circumpolar current, which led to thermal isolation of Antarctica and increased global cooling. This development was associated with a major turnover in planktic organisms, resulting in the evolution of Neogene assemblages and the eventual extinction of Paleogene assemblages. The erosive patterns of two widespread hiatuses (PH, 23.0–22.5 Ma; and NH 1, 20–18 Ma) indicate that a deep circumequatorial circulation existed at this time, characterized by a broad band of carbonate-ooze deposition. Siliceous sedimentation was restricted to the North Atlantic and a narrow band around Antarctica. A major reorganization in deep-sea sedimentation and hiatus distribution patterns occurred near the early/middle Miocene boundary, apparently resulting from changes in oceanic circulation. Beginning at this time, deep-sea erosion occurred throughout the Caribbean (hiatus NH 2, 16–15 Ma), suggesting disruption of the deep circumequatorial circulation and northward deflection of deep currents, and/or intensification of the Gulf Stream. Sediment distribution patterns changed dramatically with the sudden appearance of siliceous-ooze deposition in the marginal and east equatorial North Pacific by 16.0 to 15.5 Ma, coincident with the decline of siliceous sedimentation in the North Atlantic. This silica switch may have been caused by the introduction of Norwegian Overflow Water into the North Atlantic acting as a barrier to outcropping of silica-rich Antarctic Bottom Water. The main aspects of the present oceanic circulation system and sediment distribution pattern were established by 13.5 to 12.5 Ma (hiatus NH 3), coincident with the establishment of a major East Antarctic ice cap. Antarctic glaciation resulted in a broadening belt of siliceous-ooze deposition around Antarctica, increased siliceous sedimentation in the marginal and east equatorial North Pacific and Indian Oceans, and further northward restriction of siliceous sediments in the North Atlantic. Periodic cool climatic events were accompanied by lower eustatic sea levels and widespread deep-sea erosion at 12 to 11 Ma (NH 4), 10 to 9 Ma (NH 5), 7.5 to 6.2 Ma (NH 6), and 5.2 to 4.7 Ma (NH 7).

Geological Society of America Bulletin↗
USGS1980

A survey of image processing developments in support of remote sensing

New algorithm developments for image processing (IP) will occur throughout the 1980's, resulting from evolution in computer hardware and sensors as well as continuing research. This report will describe the areas of algorithm development that are occurring in applications, research, and operational environments. Included is an overview of image processing activities at institutions which are generally regarded as leaders in IP algorithm development and implementation. Finally, this report addresses directions in IP algorithm development that are being proposed for the EROS Data Center (EDC). The major applications of IP at EDC are developed for use in the processing, analysis, and extraction of remote sensing information from Landsat and aircraft data (platforms).

Report↗
USGS2014

Tsunamis: stochastic models of occurrence and generation mechanisms

The devastating consequences of the 2004 Indian Ocean and 2011 Japan tsunamis have led to increased research into many different aspects of the tsunami phenomenon. In this entry, we review research related to the observed complexity and uncertainty associated with tsunami generation, propagation, and occurrence described and analyzed using a variety of stochastic methods. In each case, seismogenic tsunamis are primarily considered. Stochastic models are developed from the physical theories that govern tsunami evolution combined with empirical models fitted to seismic and tsunami observations, as well as tsunami catalogs. These stochastic methods are key to providing probabilistic forecasts and hazard assessments for tsunamis. The stochastic methods described here are similar to those described for earthquakes (Vere-Jones 2013) and volcanoes (Bebbington 2013 ) in this encyclopedia.

Book chapter↗
USGS2019

Tsunamis: Stochastic models of generation, propagation, and occurrence

The devastating consequences of the 2004 Indian Ocean and 2011 Tohoku-oki tsunamis have led to increased research into many different aspects of the tsunami phenomenon. In this paper, we review research related to the observed complexity and uncertainty associated with tsunami generation, propagation, and occurrence described and analyzed using a variety of stochastic models. In each case, tsunamis generated by earthquakes are primarily considered. Stochastic models are developed from the physical theories that govern tsunami evolution combined with empirical models fitted to seismic and tsunami observations, as well as tsunami catalogs. These stochastic models are key to providing probabilistic forecasts and hazard assessments for tsunamis. The stochastic methods described here are similar to those described for earthquakes (Vere-Jones, 2013) and volcanoes (Bebbington, 2013) in this Encyclopedia.

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