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USGS2013

Identifying stakeholder-relevant climate change impacts: a case study in the Yakima River Basin, Washington, USA

Designing climate-related research so that study results will be useful to natural resource managers is a unique challenge. While decision makers increasingly recognize the need to consider climate change in their resource management plans, and climate scientists recognize the importance of providing locally-relevant climate data and projections, there often remains a gap between management needs and the information that is available or is being collected. We used decision analysis concepts to bring decision-maker and stakeholder perspectives into the applied research planning process. In 2009 we initiated a series of studies on the impacts of climate change in the Yakima River Basin (YRB) with a four-day stakeholder workshop, bringing together managers, stakeholders, and scientists to develop an integrated conceptual model of climate change and climate change impacts in the YRB. The conceptual model development highlighted areas of uncertainty that limit the understanding of the potential impacts of climate change and decision alternatives by those who will be most directly affected by those changes, and pointed to areas where additional study and engagement of stakeholders would be beneficial. The workshop and resulting conceptual model highlighted the importance of numerous different outcomes to stakeholders in the basin, including social and economic outcomes that go beyond the physical and biological outcomes typically reported in climate impacts studies. Subsequent studies addressed several of those areas of uncertainty, including changes in water temperatures, habitat quality, and bioenergetics of salmonid populations.

Washington↗

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↗

USGS1996

Kriging: Understanding allays intimidation

In 1938 Daniel Gerhardus "Danie" Krige obtained an undergraduate degree in mining engineering and started a brilliant career centered on analyzing the gold and uranium mines in the Witwatersrand conglomerates of South Africa. He became interested in the disharmony between the poor reliability of reserve estimation reports and the magnitude of the economic decisions that were based on these studies. Back at the University of Witwatersrand, he wrote a master's thesis that began a revolution in mining evaluation methods. Krige was not alone in his research. Another mining engineer, Georges Matheron, a Frenchman, thought space data analysis belonged in a separate discipline, just as geophysics is a separate branch from physics. He named the new field geostatistics. Kriging is the name given in geostatistics to a collection of generalized linear regression techniques for the estimation of spatial phenomena. Pierre Carlier, another Frenchman, coined the term krigeage in the late 1950s to honor Krige's seminal work. Matheron anglicized the term to kriging when he published a paper for English-speaking readers. France dominated the development and application of geostatistics for several years. However, geostatistics in general, and kriging in particular, are employed by few and are regarded with apprehension by many. One of the possible applications of kriging is in computer mapping. Computer contouring methods can be grouped into two families: triangulation and gridding. The former is a direct procedure in which the contour lines are computed straight from the data by partitioning the sampling area into triangles with one observation per vertex. Kriging belongs in the gridding family. A grid is a regular arrangement of locations or nodes. In the gridding method the isolines are determined from interpolated values at the nodes. The difference between kriging and other weighting methods is in the calculation of the weights. Even for the simplest form of kriging, the calculations are more demanding. The kriging system of equations differs from classical regression in that the observations are allowed to be correlated and that neither the estimate nor the observations are necessarily points - they may have a volume, shape, and orientation. The mean square error is the average of the squares of the differences between the true and the estimated values. Simple kriging, the most basic form of kriging in that the system of equations has the fewest terms, requires the phenomena to have a constant and known mean. The next step up, ordinary kriging, does not require knowledge of the population mean. The external drift method, universal kriging, and intrinsic kriging go even further by allowing fluctuations in the mean. In practice, estimation by kriging is not as difficult to handle as it may look at first glance. In these days of high technology, all the details in the procedure are coded into computer programs. When properly used, kriging has several appealing attributes, the most important being that it does the work more accurately. By design, kriging provides the weights that result in the minimum mean square error. And yes, there have been people who have tested its superiority with real data. Practice has consistently confirmed theory. Kriging is also robust. Within reasonable limits, kriging tends to persist in yielding correct estimates even when the user selects the wrong model, misspecifies parameters, or both. This property should be an incentive for the novice to try the method. Gross misuse of kriging, though, can lead to poor results, worse even than those produced by alternative methods. Kriging has evolved and continues to expand to accommodate the estimation of increasingly demanding realities. Conclusions Theory and practice show that computer contour maps generated using kriging have the least mean square estimation error. In addition, the method provides information to assess the reliability of the maps.

Fluoride↗

USGS2005

Geospatial decision support systems for societal decision making

While science provides reliable information to describe and understand the earth and its natural processes, it can contribute more. There are many important societal issues in which scientific information can play a critical role. Science can add greatly to policy and management decisions to minimize loss of life and property from natural and man-made disasters, to manage water, biological, energy, and mineral resources, and in general, to enhance and protect our quality of life. However, the link between science and decision-making is often complicated and imperfect. Technical language and methods surround scientific research and the dissemination of its results. Scientific investigations often are conducted under different conditions, with different spatial boundaries, and in different timeframes than those needed to support specific policy and societal decisions. Uncertainty is not uniformly reported in scientific investigations. If society does not know that data exist, what the data mean, where to use the data, or how to include uncertainty when a decision has to be made, then science gets left out -or misused- in a decision making process. This paper is about using Geospatial Decision Support Systems (GDSS) for quantitative policy analysis. Integrated natural -social science methods and tools in a Geographic Information System that respond to decision-making needs can be used to close the gap between science and society. The GDSS has been developed so that nonscientists can pose "what if" scenarios to evaluate hypothetical outcomes of policy and management choices. In this approach decision makers can evaluate the financial and geographic distribution of potential policy options and their societal implications. Actions, based on scientific information, can be taken to mitigate hazards, protect our air and water quality, preserve the planet's biodiversity, promote balanced land use planning, and judiciously exploit natural resources. Applications using the GDSS have demonstrated the benefits of utilizing science for policy decisions. Investment in science reduces decision-making uncertainty and reducing that uncertainty has economic value.

Boletin Geologico y Minero↗

USGS2012

Wetland fire remote sensing research--The Greater Everglades example

Fire is a major factor in the Everglades ecosystem. For thousands of years, lightning-strike fires from summer thunderstorms have helped create and maintain a dynamic landscape suited both to withstand fire and recover quickly in the wake of frequent fires. Today, managers in the Everglades National Park are implementing controlled burns to promote healthy, sustainable vegetation patterns and ecosystem functions. The U.S. Geological Survey (USGS) is using remote sensing to improve fire-management databases in the Everglades, gain insights into post-fire land-cover dynamics, and develop spatially and temporally explicit fire-scar data for habitat and hydrologic modeling.

Florida↗

USGS2013

Bathymetry, morphology, and lakebed geologic characteristics of potential Kokanee salmon spawning habitat in Lake Pend Oreille, Bayview and Lakeview quadrangles, Idaho

Kokanee salmon (Oncorhynchus nerka) are a keystone species in Lake Pend Oreille in northern Idaho, historically supporting a high-yield recreational fishery and serving as the primary prey for the threatened native bull trout (Salvelinus confluentus) and the Gerrard-strain rainbow trout (Oncorhynchus mykiss). After 1965, the kokanee population rapidly declined and has remained at a low level of abundance. Lake Pend Oreille is one of the deepest lakes in the United States, the largest lake in Idaho, and home to the U.S. Navy Acoustic Research Detachment Base. The U.S. Geological Survey and Idaho Department of Fish and Game are mapping the bathymetry, morphology, and the lakebed geologic units and embeddedness of potential kokanee salmon spawning habitat in Lake Pend Oreille. Relations between lake morphology, lakebed geologic units, and substrate embeddedness are characterized for the shore zone, rise zone, and open water in bays and the main stem of the lake. This detailed knowledge of physical habitat along the shoreline of Lake Pend Oreille is necessary to better evaluate and develop kokanee recovery actions.

Idaho↗

USGS2012

Ecosystem services valuation to support decisionmaking on public lands—A case study of the San Pedro River watershed, Arizona

This report details the findings of the Bureau of Land Management–U.S. Geological Survey Ecosystem Services Valuation Pilot Study. This project evaluated alternative methods and tools that quantify and value ecosystem services, and it assessed the tools’ readiness for use in the Bureau of Land Management decisionmaking process. We tested these tools on the San Pedro River watershed in northern Sonora, Mexico, and southeast Arizona. The study area includes the San Pedro Riparian National Conservation Area (managed by the Bureau of Land Management), which has been a focal point for conservation activities and scientific research in recent decades. We applied past site-specific primary valuation studies, value transfer, the Wildlife Habitat Benefits Estimation Toolkit, and the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) and Artificial Intelligence for Ecosystem Services (ARIES) models to value locally important ecosystem services for the San Pedro River watershed—water, carbon, biodiversity, and cultural values. We tested these approaches on a series of scenarios to evaluate ecosystem service changes and the ability of the tools to accommodate scenarios. A suite of additional tools were either at too early a stage of development to run, were proprietary, or were place-specific tools inappropriate for application to the San Pedro River watershed. We described the strengths and weaknesses of these additional ecosystem service tools against a series of evaluative criteria related to their usefulness for Bureau of Land Management decisionmaking. Using these tools, we quantified gains or losses of ecosystem services under three categories of scenarios: urban growth, mesquite management, and water augmentation. These results quantify tradeoffs and could be useful for decisionmaking within Bureau of Land Management district or field offices. Results are accompanied by a relatively high level of uncertainty associated with model outputs, valuation methods, and discount rates applied. Further guidance on representing uncertainty and applying uncertain results in decisionmaking would benefit both tool developers and those offices in using ecosystem services to compare management tradeoffs. Decisionmakers and Bureau of Land Management managers at the State-, district-, and field-office level would also benefit from continuing model improvements, training, and guidance on tool use that can be provided by the U.S. Geological Survey, the Bureau of Land Management, and the Department of the Interior. Tradeoffs were identified in the level of effort needed to parameterize and run tools and the amount and quality of information they provide to the decision process. We found the Wildlife Habitat Benefits Estimation Toolkit, Ecosystem Services Review, and United Nations Environment Programme–World Conservation Monitoring Centre Ecosystem Services Toolkit to be immediately feasible for application by the Bureau of Land Management, given proper guidance on their use. It is also feasible for the Bureau of Land Management to use the InVEST model, but in early 2012 the process of parameterizing the model required resources and expertise that are unlikely to be available in most Bureau of Land Management district or field offices. Application of past primary valuation is feasible, but developing new primary-valuation studies is too time consuming for regular application. Value transfer approaches (aside from the Wildlife Habitat Benefits Estimation Toolkit) are best applied carefully on the basis of guidelines described in this report, to reduce transfer error. The ARIES model can provide useful information in regions modeled in the past (Arizona, California, Colorado, and Washington), but it lacks some features that will improve its usability, such as a generalized model that could be applied anywhere in the United States. Eleven other tools described in this report could become useful as the tools more fully develop, in high-profile cases for which additional resources are available for tool application or in case-study regions where place-specific models have already been developed. To improve the value of these tools in decisionmaking, we suggest scientific needs that agencies such as U.S. Geological Survey can help meet—for instance, development and support of data archives. Such archives could greatly reduce resource needs and improve the reliability and consistency of results. Given the rapid state of evolution in the field, periodic follow-up studies on ecosystem services tools would help to ensure that the Bureau of Land Management and other public land management agencies are kept up to date on new tools and features that bring ecosystem services closer to readiness for use in regular decisionmaking.

Arizona;Sonora↗

USGS1980

Test and calibration of the Seismic Research Observatory

The Seismic Research Observatory (SRO) network is generating an important new data base for seismological research. The SRO systems have extended both the range and resolution of seismic measurements beyond the limits of conventional seismographs and the data are recorded in digital format making it convenient to automate processing and analysis. The SRO network now comprises 12 stations and one additional station will be installed. The data produced by the SRO network, and other digital systems being installed to supplement the SRO network, will be collected by the U.S. Geological Survey's Albuquerque Seismological Laboratory, organized into network-day tapes, and made available to research organizations throughout the world. The network-day tapes are particularly unique and useful data files as they will contain not only seismic data but all of the information needed by an analyst to interpret the data, including station constants and calibration and other instrumental parameters. Hoffman (in preperation) describe these tapes and the format used in their compilation. The global digital data base for seismology is still relatively limited in terms of both geographical and temporal coverage. For this reason there is a tendency, perhaps, to stretch the applicability of the available data beyond the intended purposes. The danger in this is compounded by the fact that computer processing and analysis often can be done without even looking at the waveforms, and it is done with deceptively high computational precision that belies the basic accuracy of the measurements. The day may be passing when seismologists have a hands-on familiarity with the data acquisition systems, but clearly it is as important as ever that they have a knowledge of the capabilities and limitations of the instruments. The primary objective of the SRO network was to lower the threshold of event detection in the long-period band. This was achieved by using a newly-developed borehole seismometer that is capable of resolving both vertical and horizontal components of earth background noise at the quietest sites on earth. Another objective was to accommodate a large range of signla amplitudes. This was achieved by using an advanced digital recording systems which provides at least 110 dB of separation between system noise levels and clipping levels in the principal bands of interest. The broadband capability was not an initial program requirement and is not being fully utilized at present, but it adds significantly to the research potential of the network. The SRO systems have proven to be reliable in operation and the general quality of the data is excellent. Every seismograph has functional limits of accuracy, and the SRO system is no exception. The chief purpose of this report is to define these limits for the SRO system and provide the most accurate calibration data currently available. At the same time we will describe the testing program in sufficient detail so that the data user can make his own judgments regarding the effectiveness and accuracy of the tests. This report is not a final statement; further work is needed in some areas to completely define the SRO system, in some cases purely for academic reasons. Refinements in calibration will appear on the network-day tapes as the new data become available.

Open-File Report↗

USGS1992

Contaminant transport and accumulation in Massachusetts Bay and Boston Harbor: A summary of U.S. Geological Survey studies

The U.S. Geological Survey (USGS) is conducting studies in Boston Harbor, Massachusetts Bay, and Cape Cod Bay designed to define the geologic framework of the region and to understand the transport and accumulation of contaminated sediments. The region is being studied because of environmental problems caused by the introduction of wastes for a long time, because a new ocean outfall (to begin operation in 1995) will change the location for disposal of treated Boston sewage from Boston Harbor into Massachusetts Bay, and because of the need to understand the transport of sediments and associated contaminants in order to address a wide range of management questions. The USGS effort complements and is closely coordinated with the research and monitoring studies supported by the Massachusetts Environmental Trust, the Massachusetts Bays Program, and by the Massachusetts Water Resources Authority. The USGS study includes (1) geologic mapping, (2) circulation studies, (3) long-term current and sediment transport observations, (4) measurements of contaminant inventories and rates of sediment mixing and accumulation, (5) circulation modeling, (6) development of a contaminated sediments data base, and (7) information exchange. A long-term objective of the program is to develop a predictive capability for sediment transport and accumulation.

Massachusetts↗

USGS1999

Proceedings of Conference on Status of Geologic Research and Mapping, Death Valley National Park

Welcome to this conference on the “Status of Geologic Research and Mapping in Death Valley National Park.” We organized this conference in an effort to foster communication and increase awareness among parties conducting geologic research in and around the park. Additionally, we hope to assess the status of geologic mapping efforts within the park boundaries in an effort to provide a framework for future discussions regarding the impact and merits of the development of a park-wide geologic map. The topics presented at this meeting reflect the breadth of recent and ongoing geologic research in and near Death Valley National Park. Sessions include (1) regional structure, tectonics, and bedrock geology; (2) Neogene basin stratigraphy, geophysics, and hydrology; (3) posters on mapping in the Death Valley region and topical ones on Death Valley National Park; (4) imagery, Quaternary stratigraphy and geomorphology, and Quaternary geochronology; and (5) paleoclimate and active tectonics. On a one-day field trip to Death Valley, we will visit areas of “type locality” status as well as areas of new research.

Open-File Report↗

USGS2023

Research needs identified for potential effects of energy development activities on environmental resources of the Williston Basin, United States

Unconventional oil and gas development that uses horizontal drilling and hydraulic fracturing is rapidly changing the landscape and exponentially increasing oil production within the Williston Basin, especially in North Dakota and eastern Montana. The activities associated with unconventional oil and gas development are complex and wide reaching and include, in part, road and well-pad construction, leaks from pits or tanks, chemical spills, discharge of wastewater, drilling before casing installation, leaks during or after hydraulic fracturing, failed casing seals, pipeline breaks, abandoned wells, deep-well disposal of flowback or produced wastewater, and induced subsurface migration pathways that can potentially adversely affect the environmental resources within the Williston Basin.

Montana, North Dakota, South Dakota↗

USGS2016

Dragonfly Mercury Project—A citizen science driven approach to linking surface-water chemistry and landscape characteristics to biosentinels on a national scale

Mercury is a globally distributed pollutant that threatens human and ecosystem health. Even protected areas, such as national parks, are subjected to mercury contamination because it is delivered through atmospheric deposition, often after long-range transport. In aquatic ecosystems, certain environmental conditions can promote microbial processes that convert inorganic mercury to an organic form (methylmercury). Methylmercury biomagnifies through food webs and is a potent neurotoxicant and endocrine disruptor. The U.S. Geological Survey (USGS), the University of Maine, and the National Park Service (NPS) Air Resources Division are working in partnership at more than 50 national parks across the United States, and with citizen scientists as key participants in data collection, to develop dragonfly nymphs as biosentinels for mercury in aquatic food webs. To validate the use of these biosentinels, and gain a better understanding of the connection between biotic and abiotic pools of mercury, this project also includes collection of landscape data and surface-water chemistry including mercury, methylmercury, pH, sulfate, and dissolved organic carbon and sediment mercury concentration. Because of the wide geographic scope of the research, the project also provides a nationwide “snapshot” of mercury in primarily undeveloped watersheds.

Fact Sheet↗

USGS2008

Fort Collins Science Center: Fiscal Year 2007 Accomplishments

In Fiscal Year 2007 (FY07), the U.S. Geological Survey (USGS) Fort Collins Science Center (FORT) continued research vital to U.S. Department of the Interior science and management needs and associated USGS programmatic goals. FORT work also supported the science needs of other government agencies as well as private cooperators. Specifically, FORT scientific research and technical assistance focused on client and partner needs and goals in the areas of biological information management, fisheries and aquatic systems, invasive species, status and trends of biological resources, terrestrial ecosystems, and wildlife resources. In addition, FORT's 5-year strategic plan was refined to incorporate focus areas identified in the USGS strategic science plan, including ecosystem-landscape analysis, global climate change, and energy and mineral resource development. As a consequence, several science projects initiated in FY07 were either entirely new research dor amplifications of existing work. Highlights of FORT project accomplishments are described below under the USGS science program with which each task is most closely associated. The work of FORT's 6 branches (Aquatic Systems and Technology Applications, Ecosystem Dynamics, Information Science, Invasive Species Science, Policy Analysis and Science Assistance, and Species and Habitats of Federal Interest) often involves major partnerships with other agencies or cooperation with other USGS disciplines (Geology, Geography, Water Resources) and the Geospatial Information Office.

Open-File Report↗

USGS1975

Audio-magnetotelluric methods in reconnaissance geothermal exploration

About three years ago, at the initiation of a major effort by the U.S. Geological Survey into studies of geothermal systems, a decision was made to evaluate the audio-magnetotelluric, AMT, technique for this application. At that time we had had no real experience with the method nor any equipment. Some prior work by Lebel [1971], and Slankis and others [1972], suggested that field operations might be slow and difficult reducing the advantages of the method. A cautious approach was used in developing equipment and field techniques until some experience was gained with the method. As no commercial equipment was available, design and fabrication of the AMT equipment to cover the frequency range 8 Hz to 18,600 Hz was done in-house. Because of the nature of the method, our approach has been to use AMT surveys for reconnaissance exploration and to follow up with other electrical methods in interesting areas. In this paper some of the results of our research are shown to illustrate the effectiveness of the technique.

Open-File Report↗

USGS1999

U.S. Geological Survey and Microsoft Cooperative Research and Development Agreement: Geospatial Data Browsing and Retrieval Site on the World Wide Web

In May 1997, the U.S. Geological Survey (USGS) and the Microsoft Corporation of Redmond, Wash., entered into a cooperative research and development agreement (CRADA) to make vast amounts of geospatial data available to the general public through the Internet. The CRADA is a 36-month joint effort to develop a general, public-oriented browsing and retrieval site for geospatial data on the Internet. Specifically, Microsoft plans to (1) modify a large volume of USGS geospatial data so the images can be displayed quickly and easily over the Internet, (2) implement an easy-to-use interface for low-speed connections, and (3) develop an Internet Web site capable of servicing millions of users per day.

Fact Sheet↗

USGS1998

U.S. Geological Survey and Microsoft Cooperative Research and Development Agreement: Geospatial Data Browsing and Retrieval Site on the World Wide Web

Fact Sheet↗

USGS2010

Unusual leg malformations in screech owls from a South Carolina Superfund site

In 1995, the discovery of leg malformations in several screech owl ( Otis asio ) nestlings and in their female parent at a Department of Energy (DOE) Superfund site in South Carolina prompted an investigation into the nature of the observed abnormalities. Surviving nestlings and the female parent were transferred to a captive screech owl breeding colony at the USGS Patuxent Wildlife Research Center, Laurel, MD. The malformed female parent and her offspring were each mated with normal owls from the colony for 3 yr. Matings of the malformed female produced five malformed and six normal owls; all owls produced by matings of normal offspring were normal. Malformed offspring were euthanized when it became apparent that their physical distress precluded survival under normal conditions of colony care. Euthanized owls were necropsied and examined for skeletal development. Detailed descriptions of eight malformed owls are presented. Results of the matings indicated that the leg malformations were caused by a genetic trait in the female parent that was heterozygous dominant. The characteristic was lethal except in occasional mild manifestations and resembled an extreme form of a dominant abnormality previously described for domestic fowl called duplicate polydactyly . Other reports of skeletal abnormalities in wild birds and potential environmental causes of genetic mutations at the DOE Superfund site are presented. Other studies performed at the DOE Superfund site do not implicate elevated (above background) ionizing radiation from 137 Cs, the dominant radionuclide where the owls were captured, as the cause of the mutation. The cause of this genetic abnormality remains unknown.

South Carolina↗

USGS2006

Preliminary integrated geologic map databases for the United States: Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, Rhode Island and Vermont

The rapid growth in the use of Geographic Information Systems (GIS) has highlighted the need for regional and national scale digital geologic maps that have standardized information about geologic age and lithology. Such maps can be conveniently used to generate derivative maps for manifold special purposes such as mineral-resource assessment, metallogenic studies, tectonic studies, and environmental research. Although two digital geologic maps (Schruben and others, 1994; Reed and Bush, 2004) of the United States currently exist, their scales (1:2,500,000 and 1:5,000,000) are too general for many regional applications. Most states have digital geologic maps at scales of about 1:500,000, but the databases are not comparably structured and, thus, it is difficult to use the digital database for more than one state at a time. This report describes the result for a seven state region of an effort by the U.S. Geological Survey to produce a series of integrated and standardized state geologic map databases that cover the entire United States. In 1997, the United States Geological Survey's Mineral Resources Program initiated the National Surveys and Analysis (NSA) Project to develop national digital databases. One primary activity of this project was to compile a national digital geologic map database, utilizing state geologic maps, to support studies in the range of 1:250,000- to 1:1,000,000-scale. To accomplish this, state databases were prepared using a common standard for the database structure, fields, attribution, and data dictionaries. For Alaska and Hawaii new state maps are being prepared and the preliminary work for Alaska is being released as a series of 1:250,000 scale quadrangle reports. This document provides background information and documentation for the integrated geologic map databases of this report. This report is one of a series of such reports releasing preliminary standardized geologic map databases for the United States. The data products of the project consist of two main parts, the spatial databases and a set of supplemental tables relating to geologic map units. The datasets serve as a data resource to generate a variety of stratigraphic, age, and lithologic maps. This documentation is divided into four main sections: (1) description of the set of data files provided in this report, (2) specifications of the spatial databases, (3) specifications of the supplemental tables, and (4) an appendix containing the data dictionaries used to populate some fields of the spatial database and supplemental tables.

Connecticut, Maine, Massachusetts, New Hampshire, ↗