estimate of the remaining undiscovered oil and natural gas for the 38 petroleum provinces, as defined in Survey Circular 860, within which the Wilderness Lands occur. The undiscovered recoverable oil, reported at the 95- and 5-percent probability levels, for the Wilderness Lands in the Western States is estimated to range from 0.555 to 1.490 billion barrels with a mean estimate of 0.834 billion barrels. The undiscovered recoverable natural gas reported at the same probability levels is estimated to range from 5.536 to 16.639 trillion cubic feet with a mean estimate of 9.729 trillion cubic feet. For comparative purposes, the total undiscovered recoverable oil and natural gas resources estimated by the Geological Survey for the 38 western petroleum provinces in which these Wilderness Lands occur are 25 to 45 billion barrels of recoverable oil with a mean estimate of 31 billion barrels and 141 to 256 trillion cubic feet of natural gas with a mean estimate of 183 trillion cubic feet. An estimated percentage range (reported at the 95- and 5-percent probability levels) of the amounts of petroleum resources within these western provinces which may occur within designated and proposed Wilderness Lands is 2.2 to 3.3 percent of the total undiscovered recoverable oil and 3.9 to 6.5 percent of the total undiscovered recoverable gas.

These results have been published as Survey Circular 902. The circular docu

ments the entire study: the methodology, procedures, and digital cartography; a description of the geology and geologic framework for each State, along with an explanation of the interpretative geology and evaluation of the petroleum potential within the locale of each of the wilderness tracts; tables and graphs of the results of the qualitative assessments tabulated by acreages; and the quantitative estimates reported as probability distributions.

A series of maps, one for each Western State, will be published separately as Survey Miscellaneous Investigations Series Maps I-1537 through I-1547. Each map will show, in color and at a scale of 1:1,000,000, the location and Bureau of Land Management tract identification and qualitative petroleum potential of the Wilderness Lands studied, the boundary locations of other major Federal and Indian lands, the boundaries and identification of the petroleum provinces, and other base information (see the figure). A pamphlet will accompany each State map describing the geology of the State and the local geology relative to the position of the wilderness tracts and their petroleum potential.

During the next several years, a similar program is scheduled to complete the petroleum resource assessments of Wilderness Lands in Alaska and other major Federal lands in Alaska and the Western United States.

Immediately following the oil embargo of 1973, the United States moved rapidly to increase the use of alternative sources of energy. During the balance of the 1970's, a significant amount of new exploration for coal resources was accomplished under various governmental and industrial programs designed to accelerate development of the Nation's vast reserves of this fuel. In 1974, the U.S. Geological Survey began the development of the National Coal Resources Data System to provide a central repository for all previously acquired public coal data as well as for additional data acquired in the future. It is a user-oriented computerized data system for the inventory and analysis of the Nation's coal resources. The system also is designed to summarize data on coal resources and to make these data accessible to a large audience in a standardized format so that they can be used in formulating and implementing the Nation's energy policy.

The coal resources of the United States are large, and the task to assess them is challenging. Current estimates indicate that there are nearly 4 trillion short tons of coal in the United States; however, less than one-half have been identified by systematic mapping and exploration. The existence of the remainder is extrapolated from current data. In addition, the coal resource information included in existing summaries is often inadequate because of outdated information, lack of uniform standards, insufficient detail, and lack of data. The scope and complexity of the task to create a modern U.S. coal resource assessment are clear from the following facts: coal-bearing rocks underlie approximately 13 percent of the land area in the United States, the strata may contain more than 50 coalbeds or zones at depths of 6,000 or more feet, and the geological structure ranges from regular and flat lying to highly folded and faulted.

The system is designed to be openended so that it can accommodate growth in quantity and type of data stored and in facilities to make these data accessible. Presently, the goal of developing a system that can statistically, tabularly, and graphically analyze coal data has been met. The major goal to calculate coal resources according to the approved methods of the Geological Survey has also been attained.

Research and development on the system has also provided tools which can be and are applied to available data for other research and planning needs; for example, capabilities of the data system can be used to study geochemical constituents and the shape, size, and distribution of coal and overburden layers for use in making models of coal occurrence. The system also improves prediction of additional coal resources in unexplored areas and can aid in mine reclamation plans.

Data from the various parts of the system may be integrated to demonstrate the relationship of several different elements; for example, trace element and petrologic data can be overlayed with stratigraphic data to generate prediction models for coal quality variation on a bed or multiple bed basis. These facilities allow integration of quantity and quality data for coal resource assessments. Coal quality data (such as sulfur content) are essential to decisionmakers who must assess the environmental impact of coal mining and use. As the data base grows, it is expected to be of considerable value in industry planning for exploration and development of new

resources.

The problem of assessing the Nation's coal resources is a multifaceted one with efforts from many contributors aiding in the solution. Coordination between groups within and external to the Geological Survey has been of great value. Substantial contributions have been made by the Information Systems and National Mapping Divisions. To augment the Federal coalmapping/data-gathering programs, the expertise available in State geological agencies has been used to carry out a large part of the data collection. At this time, the Survey is funding 18 State geological agencies or universities to collect and submit available coal resource-related data for entry into the NCRDS. For the majority of the States, this is a 5-year program. As of September 1983, information on approximately 65,000 drill holes or outcrop observations have been entered into the system.

The U.S. Geological Survey is firmly committed to the continued improvement of the National Coal Resources Data System to serve current and future needs for U.S. coal resource assessment.

Landslide Crisis in Utah

Heavy precipitation in Utah during the 1982-83 winter season, beginning with a major storm in September 1982, produced a near record snowpack in the higher elevations. Rapid melting combined with spring snow and rainstorms triggered damaging debris flows and landslides in unprecedented numbers.

The U.S. Geological Survey responded to requests from the Utah Geological and Mineral Survey and the Federal Emergency Management Agency for geological help in the emergency response to the landsliding. During the period of this emergency, eight geologists and engineers with support staff from the Survey's regional centers in Denver and Menlo Park and from the University of Cincinnati and the Los Angeles County Flood Control District provided various types of technical assistance. This team provided assessments of threats to life and property from different types of landslides between mid-April and mid-June 1983 and evaluated potential problems that could be triggered by future cloudbursts.

The first indications of impending problems materialized with the reactivation of a large (106-million-cubic-foot) landslide near Thistle, Utah. The landslide blocked Spanish Fork Canyon which created a large lake and cut off a major transcontinental railroad line and highway access to central Utah which prevented shipment of coal and other supplies; costs of damage have exceeded $100 million. The Survey responded to a request from the Utah Survey to provide assessments of the landslide conditions at Thistle and a detailed map of the bedrock geology in the vicinity of the landslide. The geologic map, published by the Utah Survey, has been useful in selecting routes for bypass tunnels for the railroad and for estimating tunneling conditions.

Toward the end of May, a week of very warm weather accelerated melting of the snowpack triggering numerous landslides in the Wasatch Mountains and Wasatch Plateau that mobilized into debris flows. North of Salt Lake City, debris flows crashed into the communities of Bountiful and Farmington, destroying homes and forcing the evacuation of hundreds of residents. Geologists from the Geological Survey assisted the Utah Survey in hazard appraisals in areas of population concentration. The lack of fatalities caused by landsliding was due in large part to the well-organized response of the Utah

Survey in directing repeated evaluations of hazards in critical areas and to cooperation with appropriate local, State, and Federal emergency management agencies.

Two other potential disasters involved reservoirs in the Wasatch Plateau that could have been breached or partly filled by landslides, releasing a wall of water that would probably have caused extensive damage in communities downstream. One of the reservoirs was partially drained and the other was closely monitored to make certain that the hazard did not become worse. Other problems involved the potential for landslides blocking creeks and forming dams which, if breached, would release a large volume of water and debris in a short time. Still other problems involved landslides that disrupted road systems and water supplies.

After the most pressing emergency situations had abated, the Utah Survey asked the Geological Survey to determine whether additional landslide disasters were in the early stages of formation in other areas of the State and which areas in the State should be photographed for shortand long-term assessment of landslide potential. One major problem was the need to cover 82,000 square miles in a short time with limited funds and manpower. To make the most rapid survey possible, two geologists rode in a light aircraft, one of them plotting areas of landsliding on a 1:100,000-scale topographic map and the other taking pictures of these areas and describing the localities in a tape recorder. At the end of 4 days, a 1:500,000-scale map was prepared showing all the known landslide areas along with an evaluation of which areas seemed to be highest in priority for immediate hazard assessment on the ground and for longer term landslide assessment using vertical aerial photography.

Another major problem was to determine the hazard represented by partly detached landslides that occupied valleys upstream from several communities north of Salt Lake City. The concern was that, during summer rainstorms, these landslides could become debris flows, which would be similar to the destructive ones of May and June. Although geologists and engineers are able to predict the stability of a particular hillside if information on the strength, volume, and geometry of the materials are known, the prediction of mobilization into a debris flow is still a research problem.