Geology topics

Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey

Publications and source records attributed to Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey.

At least 847 records · Page 47Linked to original sources

USGS1997

Looking for an old aerial photograph

Attempts to photograph the surface of the Earth date from the 1800's, when photographers attached cameras to balloons, kites, and even pigeons. Today, aerial photographs and satellite images are commonplace. The rate of acquiring aerial photographs and satellite images has increased rapidly in recent years. Views of the Earth obtained from aircraft or satellites have become valuable tools to Government resource planners and managers, land-use experts, environmentalists, engineers, scientists, and a wide variety of other users. Many people want historical aerial photographs for business or personal reasons. They may want to locate the boundaries of an old farm or a piece of family property. Or they may want a photograph as a record of changes in their neighborhood, or as a gift. The U.S. Geological Survey (USGS) maintains the Earth Science Information Centers (ESIC?s) to sell aerial photographs, remotely sensed images from satellites, a wide array of digital geographic and cartographic data, as well as the Bureau?s wellknown maps. Declassified photographs from early spy satellites were recently added to the ESIC offerings of historical images. Using the Aerial Photography Summary Record System database, ESIC researchers can help customers find imagery in the collections of other Federal agencies and, in some cases, those of private companies that specialize in esoteric products.

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USGS1997

How to obtain aerial photographs

The U.S. Geological Survey's (USGS) Earth Science Information Center (ESIC) maintains an informational data base of aerial photographic coverage of the United States and its territories that date back to the 1940's. This information describes photographic projects from the USGS, other Federal, State, and local government agencies, and commercial firms.

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USGS1997

The Universal Transverse Mercator (UTM) grid

The most convenient way to identify points on the curved surface of the Earth is with a system of reference lines called parallels of latitude and meridians of longitude. On some maps the meridians and parallels appear as straight lines. On most modern maps, however, the meridians and parallels may appear as curved lines. These differences are due to the mathematical treatment required to portray a curved surface on a flat surface so that important properties of the map (such as distance and areal accuracy) are shown with minimum distortion. The system used to portray a portion of the round Earth on a flat surface is called a map projection.

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USGS1997

Changing Perceptions of World Oil and Gas Resources as Shown by Recent USGS Petroleum Assessments

The U.S. Geological Survey (USGS) periodically conducts geology-based assessments of the oil and gas resources of the world in recognition of the fact that the United States economic security is closely linked to energy resources outside the United States. Four such petroleum assessments have been published in recent years (Masters and others, 1984, 1987, 1991, and 1994). A summary of these assessments (table 1) indicates the magnitude of world conventional oil and gas resources, as perceived in the 1980s and 1990s by the USGS. These four successive world petroleum assessments evidence changes in perception through time. The assessments were prepared using a consistent methodology by the same core group of geologists. Because of this continuity, differences among the four assessments can be largely attributed to an evolving understanding of world recoverable oil and gas resources rather than to procedural or philosophical changes. In this fact sheet, some of the trends in the estimates of table 1 are examined with a view toward better understanding world oil and gas resources in the context of the next few decades.

Fact Sheet↗

USGS1997