combining Landsat data with other digital data sets, such as elevation data, for analysis in automated geographic information systems. HIGH PLAINS REGIONAL AQUIFER SYSTEM ANALYSIS PROJECT • The High Plains, a 174,000-squaremile area of flat to gently rolling terrain east of the Rocky Mountains, is underlain by unconsolidated alluvial deposits that form a water-table aquifer capable of sustaining well yields of 100 to more than 1,000 gallons per minute. Irrigation from this aquifer has made the High Plains one of the Nation's leading agricultural areas. In 1978, as part of the Regional Aquifer System Analysis (RASA) Program, the U.S. Geological Survey began a study of the High Plains aquifer to understand the flow system and to evaluate the effects of the irrigation development on a regional scale. This study indicated that data on pumpage for irrigation and recharge to the aquifer from irrigation return flow are essential to evaluate water-level declines due to irrigation development; these data, however, were not readily available. To develop a method of estimating these data with an acceptable confidence level, a follow-up project to the RASA Program, Phase II, was started in 1983, and two areas, one in the southern High Plains of Texas and the other in the northern High Plains of Nebraska, are being studied currently. ENERGY GEOLOGIC STUDIES • During fiscal year 1984, several geological and hydrological studies at Newberry Volcano, Oregon, were completed under the Geothermal Research Program. Results of these studies provided (1) evidence from hydrothermal alteration analyses that a hot, young hydrothermal system still is evolving beneath the volcano, (2) a conceptual model of the shallow hydrothermal system that estimates fluid recharge to the system, and (3) a related numerical model of conductive heat flow that refines estimates of the age and size of a shallow magma chamber which would be the heat source for the hydrothermal system. These studies followed test drilling by the U.S. Geological Survey at Newberry Volcano in 1981 that demonstrated that high-temperature geothermal fluids exist in permeable rocks beneath a cool zone of hydrologic masking. The investigations at Newberry have substantiated the concept that the potential for exploitable geothermal energy in the Cascade Range of the Pacific Northwest is high and have provided incentives for additional industry exploration in the region. • Assessment of the undiscovered oil and gas resources of the United States and worldwide continued in fiscal year 1984. A major focus has been on the pattern of worldwide hydrocarbon exploration drilling, and methods of predicting oil and gas reserves from past production records are being developed. Results of this research indicate that areas for new exploration still are expanding at the relatively rapid rate of 50,000 square miles per year (now covering 1.5 million square miles outside North America and Communist countries), but a large fraction of new additions to reserves may be generated from already discovered fields. Another topic being studied is the pattern of oil and gas field size distributions in mature basins. The results of this study will allow future regional resource estimation methods to be expanded to include predictions of field size distributions as well as aggregate amounts of petroleum. • Two maps showing the location and names of basins and the total thickness of sedimentary rocks in the conterminous United States and two maps showing the location of wells drilled for oil and gas deeper than 15,000 and 20,000 feet, respectively, in the onshore and offshore conterminous United States were released January 1984. These maps are now being refined and, when formally published, will be the first components of an Atlas of Oil and Gas Data. DIGITAL SYSTEMS • Digital systems used by the U.S. Geological Survey to collect, process, edit, and display digital cartographic data are in a state of rapidly changing technology. During the 1970's, such systems were simply tools to digitize manually features from maps and aerial photographs and to store the data onto magnetic tapes. Currently, systems are available which not only collect data but have the interactive capability to display and edit the data, greatly improving the accuracy and economy of producing digital data with a high level of data integrity and completeness. One type of digital system is used to scan maps automatically and uniformly, to digitize features of a particular overlay or of a certain color, and to store the data in a televisionlike format. An associated computer and an edit station then are used to correct errors, to label features, and to reformat the data. Another type of digital system is used to trace lines and to digitize their coordinates directly, with feature labels or attributes being added concurrently. The digitizing may be accomplished manually and then viewed and edited interactively, or it may be accomplished automatically by a line-following sensor with some interactive assistance. Edit systems now have color capability to aid in complex interpretation and computers large enough for extensive processing and analysis. As digital systems continue to evolve, the economic acquisition of digital data, the plotting of cartographic products, and the application of data in geographic information systems for resource analysis will increase dramatically. These evolving capabilities will revolutionize map production and geographically based resource analyses. MOVEMENT AND FATE OF CONTAMINANTS FROM TO GROUND WATER, • Since 1936, secondarily treated domestic sewage has been discharged to the ground on surface sand beds at a sewagetreatment plant at Otis Air Force Base, Massachusetts. Infiltration of the sewage through sand beds to an underlying sand and gravel aquifer and the subsequent movement of the sewagecontaminated ground water in a southerly direction have caused a plume of contamination to form that is 3,000 feet wide, 75 feet thick, and more than 11,000 feet long. Most contaminants move readily through the sand and gravel that make up the aquifer on Cape Cod, and little discernible attenuation by sorption of solutes on the aquifer material is evident. Transverse and longitudinal spreading of the plume is significant, but little vertical mixing occurs. After 10,000 feet of movement, the plume is only about 75 feet thick, with a core zone 20 to 30 feet thick where the contaminants remain at concentrations more than one-fourth of what they are in the treated sewage. LAND-RESOURCE INVESTIGATIONS • An extensive subduction melange complex, the Macon melange, which underlies at least 5,000 square miles in Georgia, has been recognized through detailed geologic mapping conducted under the Geologic Framework Program in the Georgia Piedmont. A melange is a deformed mixture of rocks made up of slabs and blocks, some of them miles in length, that have been mixed together by movements between the continent-sized plates that form the Earth's crust. The Macon melange may be comparable in size to the Franciscan melange energy exploration and geologic • Continued detailed geologic mapping • An early 20th century uplift of a major part of southern California closely matches a mid-20th century uplift in areal extent and magnitude, as well as in its history of episodic growth and partial collapse. The detection of this earlier uplift, together with the previous recognition of its modern analogue in southern California, demonstrates that a very large part of southern California, including the major mountain ranges bounding the north side of Los Angeles, has sustained cyclic deformation over a period of about 50 years. This finding is critical to an assessment of the tectonic evolution of the boundary between the actively moving North American and Pacific crustal plates and will be an important consideration for any tectonic model used for earthquake prediction in this heavily populated and economically vital region. • Exciting new analytical techniques are being employed which now make it possible to determine the ages of rocks and sediments that previously could not be dated. An example is the laser argon40-argon-39 method, by which ages of single grains of mica can be measured without having to go through the time-consuming and expensive process of separating the mineral from the rock. This dating process aids greatly in understanding the chronology of mineralized zones where micas are present in such small quantities or are so small that they cannot be separated for conventional dating. LASER OPTICAL DISK STORAGE • Research and development are underway to implement laser optical disk storage technology for the storage, retrieval, and maintenance of the rapidly expanding National Digital Cartographic Data Base. Optical disk technology involves the use of laser beams to read and record digital information onto and from the surface of a rotating reflective disk. The optical disk unit records information on the reflective surface by burning microscopic patterns of digitally encoded pits with a high-powered laser. The unit reads the information from the disk with a second U.S. Geological Survey scientist with ablatograph that will record ice melt on Columbia Glacier, (Photograph by Mark E. Meier, U.S. Geological Survey.) laser which illuminates the burned areas, reflects the encoded pattern to a photoelectric sensor, and converts the resulting electrical impulses to digital signals for data processing. This promising technology offers significant advantages over conventional storage and retrieval devices. For instance, magnetic tapes and disks normally degrade after 2 or 3 years, while optical disks are expected to last at least 10 years. Optical technology also offers far higher data storage capability. A single disk can store up to 4 × 109 characters of data-an amount equivalent to 40 magnetic tapes. When the new software is developed, the use of optical disks will reduce significantly the costs of the National Digital Cartographic Data Base and other archival storage. Current research and development efforts are moving toward improving data structures, data access methods, and data processing procedures to efficiently use the technology. DISINTEGRATION OF THE LOWER REACH OF COLUMBIA GLACIER, ALASKA, NOW UNDER WAY • During the time in the mid 1970's when the Trans-Alaska Pipeline terminal was being built, ice in the shipping lanes of Valdez Arm was encountered rarely and was not considered to be a problem. Now, however, icebergs are seen frequently in Valdez Arm, and, occasionally, tankships have to be diverted or delayed because of ice. Icebergs in Valdez Arm are increasing because the Columbia Glacier is beginning to disintegrate rapidly, resulting in a large increase in the breaking off (calving) of icebergs. This rapid disintegration was predicted by U.S. Geological Survey glaciologists in 1980. Never before have scien tists been able to observe the beginning of glacier instability and drastic retreat, and careful observations of this glacier are adding much valuable new information, some of which is surprising and unanticipated. MAPPING OF IRRIGATED CROPLAND WITH LANDSAT DIGITAL DATA • Research in the use of multispectral Landsat digital data has proved amount of land that is irrigated and measurements were combined with estimated pumpage rates to successfully provide input to the hydrologic model. This method provided classification of the cropland rapidly and accurately. PLANETARY GEOLOGY • The first in a series of three 1:15,000,000-scale geologic maps of Mars made from Viking Orbiter spacecraft images has been completed for the National Aeronautics and Space Administration. The series will supersede the Geologic Map of Mars (1:25,000,000 scale) completed in 1978 from Mariner 9 spacecraft pictures. The new map of the Western Equatorial Region shows 60 individual rockstratigraphic units and includes descriptions of major tectonic, volcanic, and fluvial (river development) episodes interpreted from the spacecraft image data. The expanding Martian data base includes a new series of photomosaics and a new planetwide topographic data control net. • Evidence of prehistoric, large-scale climate change was observed from space shuttle orbit. Ground investigation of buried ancient stream channels in the eastern Sahara dicovered by U.S. Geological Survey and other scientists resulted from analysis of images made by the Imaging Radar System in an early 1982 shuttle flight. The field observations, in addition, are providing important new data to evaluate subsurface radar responses for water and mineral resource potential, and for defining habitation patterns and migration paths of early stone age man about 200,000 years ago. |