FEDERAL EXCHANGE FORMAT The recent nuclear accident at Chernobyl in the Soviet Union, together with the 1979 accident at the Three Mile Island nuclear plant in Pennsylvania, has focused national attention on how authorities might expedite the evacuation of citizens from an affected area. Ideally, authorities should have immediate access to information regarding the location of people within a threatened area, available transportation routes out of the area, weather patterns that influence radiation dispersal, and the direction and rate of possibly contaminated streamflow. Unfortunately, all the needed information is not found in a single, comprehensive data base, nor is it available in compatible data structures and formats. In order to merge different yet related types of data into a single data base for rapid computer analysis, all the various data elements must be uniform in structure for computerized handling. As a result of discussions concerning the exchange of digital cartographic information, the Office of Management and Budget created the Federal Interagency Coordinating Committee on Digital Cartography in 1983. Consisting of 27 Federal agencies and chaired by the Geological Survey, the committee was charged with the critical task of "developing and adopting, for use by all Federal agencies, common standards of content, format, and accuracy for digital cartographic data to increase its interchangeability and enhance its potential for multiple use." A first step toward meeting these standards is delineating the data structures and formats needed to facilitate the interagency exchange of computerized cartographic and geographic data (termed "spatial" data). The prototype Federal Geographic Exchange Format, developed by the committee, is such a step. In developing the format, the committee had to keep in mind several major areas of concern. First, the format chosen would have to accommodate existing spatial and earth-science data bases as much as possible to avoid costly reentry of data. Second, the format would have to be flexible enough to handle future spatial data base developments. Finally, the format should not be come unwieldy in terms of complexity and implementation costs. Thus, simplicity and flexibility became the primary design goals. Design of the prototype Federal Geographic Exchange Format was completed in fiscal year 1986, and testing is being Federal agencies in different parts of the conducted within and between many country. Hydrographic, topographic, geologic, hydrologic, demographic, administrative, navigational, transportation, land survey, soils, natural resources, and other types of data are all being used to test the this prototype testing is completed in 1987, capabilities of the exchange format. Once the Survey will be responsible for finalizing an operational version of the Federal Geographic Exchange Format, the ultimate goal being to make the format a Federal Information Processing Standard for the exchange of digital spatial data. Interest in the Federal Geographic Exchange Format has now gone beyond national bounds into the international arena, since the Federal Geographic Exchange Format might become the standard exdata base. Incidents such as the release of change format for a worldwide cartographic radiation that travels worldwide, unconstrained by political borders, strongly enforce the need for such an international data base and a standardized means of exchanging information. NEW MAP OF GLACIAL DEPOSITS PROVIDES DATA FOR LAND PLANNING DECISIONS A geologic map showing a threedimensional perspective of both surficial and subsurface unconsolidated deposits over much of the northern conterminous United States has been completed by the U.S. Geological Survey and is being prepared for publication. The map area is the region once covered by the thick continental ice sheets in the United States east of the Rocky Mountains and in parts of Canada, the Great Lakes, and the Atlantic offshore (see fig. 2A for location of map coverage). The map shows the character of the surficial sediments, the total thickness of glacial, glacially related, and postglacial sediments, and certain well-mapped buried units. Figure 2. Map area and format for the map of the glaciated United States east of the Rocky Mountains. This map conveys, for the first time, the regional distribution and thickness of glacial and postglacial sediments, which previously had been shown in detail on local maps only. The data shown on the map were compiled and reinterpreted from approximately 850 existing maps, reports, and unpublished data sources. Discussions with geologic authorities for each State enhanced the quality of reinterpretation and map compilation. Most thickness data were taken from reports and drill hole logs and had not been published in map form before. Because a uniform classification system that could encompass differing styles of geologic mapping had to be developed for surficial units in the map area, many map patterns are different from those on existing maps. For example, the glacial history of New England is quite different from that of the Great Plains States, the result being contrasts in the glacial sediments and mapping emphases in the two regions. The uniform classification emphasizes similar aspects of the deposits in these areas and should, therefore, add to the effectiveness and accuracy of regional assessments. Portraying not only the surficial geology but also the nature and extent of geologic units in the subsurface, this map is in essence a three-dimensional view of the outermost layer of the Earth. A small portion of the map is shown in figure 2B. This area, located in southwestern Ohio, was covered by ice during at least two major glacial episodes. Before and between glaciations, a network of streams and valleys existed; the major river in that network flowed past Hamilton and Dayton, Ohio, roughly where the Great Miami River flows today. This ancient valley and its tributaries contain a major aquifer system that serves the area's industrial centers. When the most recent (late Wisconsinan) glacier flowed over the area about 21,000 years ago, most of the valleys were covered over with till, a poorly sorted ice-lain sediment; in many valleys, sandy river sediments were not removed by the glacier and today serve as aquifers buried beneath the till (fig. 2B). Sandy sediments in the major river valley commonly occur from the land surface down to bedrock, because this valley was the course through which water from the melting, retreating glacier was channeled. This map is the first regional approximation of the three-dimensional distribution of sediments over a very large area and is intended to supplement, not replace, the more detailed work on which it is based. Detailed mapping, particularly in populated areas, is necessary to address the site-specific geologic problems related to man's activities at and beneath the land surface. Detailed mapping is also required to interpret the geologic history and framework of sediments for a region. Regional maps such as the one discussed here place local detailed mapping in a regional context, permit the extrapolation of data into unmapped areas, and depict large-scale regional geologic features that are beyond the scope of detailed local mapping. A regional map in many cases will point out a problem or relationship that is not apparent on a detailed map and thus permits information from the detailed map to be used correctly to solve problems arising from site-specific activities. Surficial geologic and sediment thickness mapping and the ability to predict where buried aquifers occur are vital tools for solving problems such as the siting of landfills and construction, the evaluation of mineral resources, and the evaluation of ground-water resources and their vulnerability to contamination. Approximately 40 percent of the population in the conterminous United States resides within the region covered by the map, which is less than 25 percent of the total area of the country. Population density this high necessitates regional cooperation, across State and other political boundaries, in planning and in assessing problems involving waste disposal and ground-water management, since the waste of one community can unintentionally contaminate the drinking water of another. Information on the map indicates the thickness of the unconsolidated sediments (which contain numerous aquifers) and also the extent of certain major aquifers; this information can be used to supplement detailed mapping in predicting contaminant movement through the unconsolidated sediments. The thickness and composition of these sediments may also influence the generation and migration of radon gas and mitigate the effect of acid rain. In addition to its applications for resources and land planning, this new map should help to stimulate research and more detailed HYDROCHEMICAL cultural, and other data sets. These derivative RESPONSE OF A SMALL The hydrologic response and the spatial and temporal patterns of stream chemistry were used to identify several key processes regulating stream acidification and major ion chemistry in a 100-acre research watershed (fig. 3A) at the Panola Mountain State Conservation Park near Stockbridge, Ga., Figure 3. A Gaging stations Continuous stream 50 NHA Ca2+ DISCHARGE - 50 11 12 10:00 about 16 miles southeast of Atlanta. During which was highly correlated with the vals as short as minutes. Runoff that collected at the base of the granite outcrop generally was more acidic (pH 4.1-4.6) than the rain (pH 4.6). Sulfate, the dominant acid anion in precipitation, was the highest of any solute in the runoff and the rain. The decrease in acidity and sulfate concentrations from initial levels in the runoff to a minimum before peak rainfall intensity suggests that dry deposition of SO, during the previous 8-day period was a major source of acidity (fig. 3C). More than 50 percent of the runoff acidity was attributed to the dry deposition of SO2 plus the wet deposition of sulfuric acid. SHADED-RELIEF Applications research in generating shaded-relief products using Digital Elevation Model data has seen many advances recently. Alternative methods for simulating illumination and shadowing on terrain features, including a convolution by wedgefilter technique and the cosine of the angle between slope-normal and the illumination direction method, have been investigated. The cosine approach has been selected as the more flexible and responsive technique because of greater control in positioning the illumination source, adding ambient light, and exaggerating elevation values. A shaded-relief image for the entire State of South Dakota was generated by using the cosine technique; county boundaries were added to the final product to aid in identifying specific locations within the State (fig. 4). Work on the South Dakota shaded-relief image led to research on techniques to enhance standard products that include large areas of relatively low relief. Topographic detail in lowland areas can be enhanced by converting elevations to logarithmic values before the shadedrelief image is generated. This technique was used successfully on the Chattanooga, Tenn., 1:250,000-scale quadrangle to enhance the lowlands in the Valley and Ridge province. Obtaining a correct impression of the relative relief of large areas from shadedrelief images can be difficult. To solve this problem, selected ranges of elevation are color coded by transforming the color elevation image to hue, intensity, and saturation separates. The color-coded |