Decade of North American Geology Geologic Map of North America—Perspectives and explanation
John C. Reed, Jr., John O. Wheeler, Brian E. Tucholke, Will R. Stettner, David R. Soller, 2005. "Decade of North American Geology Geologic Map of North America—Perspectives and explanation", Decade of North American Geology Geologic Map of North America—Perspectives and explanation, John C. Reed, Jr., John O. Wheeler, Brian E. Tucholke, Will R. Stettner, David R. Soller
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The idea that the Decade of North American Geology (DNAG) project should include preparation of a new geologic map of the continent was conceived early in the DNAG planning process. The minutes of a meeting of the Steering Committee chaired by L.T. Silver on January 29–30, 1980, record that:
It was generally agreed that the geographic scope [of the DNAG project] would extend from the Arctic Ocean on the north to the southern limits of the Caribbean plate; from the Mid-Atlantic ridge on the east to the Pacifi c plate in the approximate vicinity of Hawaii. The emphasis would be placed on the geology of the continent; the adjacent sea fl oor would be carried as it is related to the continental story.…
At the same meeting “the need for a new geologic map was discussed extensively with some disagreement.” However, at a meeting in May of the same year, a subcommittee appointed to examine the need for a new geologic map unanimously supported the proposal. It estimated that publication costs might be as much as $200,000, compilation costs might be $500,000, and the time required for compilation would be about 5 years. The Steering Committee agreed that a new geologic map covering the area of the DNAG project was needed, and placed compilation of the map on the list of official DNAG efforts.
By May 1981, the compilers and principal cartographers had been selected, the base map chosen, the essential features of the explanation agreed upon, and
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“The new Geologic Map of North America covers ~15% of Earth’s surface and differs from previous maps in several important respects: It is the first such map to depict the geology of the seafloor, the first compiled since the general acceptance of plate-tectonic theory, and the first since radiometric dates for plutonic and volcanic rocks became widely available. It also reflects enormous advances in conventional geologic mapping, advances that have led to a significant increase in the complexity of the map. The new map, printed in 11 colors, distinguishes more than 900 rock units, 110 of which are offshore. It depicts more than seven times the number of on-land units as are shown on its immediate predecessor, as well as many more faults and additional features such as volcanoes, calderas, impact structures, small bodies of unusual igneous rocks, and diapirs.
When displayed at earth science institutions and libraries, this map is sure to impress viewers with the grand design of the continent and may inspire some to pursue the science of geology. The new Geologic Map of North America is also a “thinking map,” a source for new interpretations of the geology of North America, insights into the evolution of the continent, new exploration strategies for the discovery of mineral and energy resources, and the development of better ways to assess and mitigate environmental risks and geologic hazards.3 sheets (North, South, and Legend), approximately 74 x 40 inches.”