New Geologic Map Of North America Illustrates Advances In Geoscience

TECTONICS

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.

Boulder CO (SPX) Feb 02, 2005
The last definitive geologic map of North America was published before the theory of plate tectonics was widely accepted, back in the days when impact craters were known simply as "anomalies" and knowledge of ocean floor geology was in its infancy.

This week the Geological Society of America (GSA) introduces the 2005 Geologic Map of North America. It's like no other in its representation of the grand architecture of the continent.

A work of beauty as well as science, the map is printed in 11 colors with approximately 700 shades and patterns. It distinguishes more than 900 rock units, 110 of which are off-shore.

It depicts more than seven times as many on-land units as the 1965 map. Perhaps its most significant additions are detailed features of the seafloor, including spreading centers, seamount chains, and subduction zones.

"Our knowledge of the Earth and how it works has grown exponentially over the last 40 years," said Jack Hess, Executive Director of GSA. "We are pleased and excited to offer this great mapping achievement to the scientific community."

The map is the result of a cooperative effort by GSA, the U.S. Geological Survey (USGS), the Geological Survey of Canada (GSC), and the Woods Hole Oceanographic Institution (WHOI).

John C. Reed Jr. (USGS) and John O. Wheeler (GSC) compiled the on-land geology, while Brian E. Tucholke (WHOI) mapped and compiled the seafloors. The Pikes Peak Lithographing Company, Colorado Springs, Colorado, printed the map.

More than twenty years in the making, the map illustrates approximately 15% of Earth's surface. It spans an area from the North Pole to Venezuela and from Ireland to Siberia.

The map's developers describe it as a source for new interpretations of North American geology and insights into the evolution of the continent.

"It will also aid in the discovery of mineral and energy resources, increase our ability to understand and mitigate geological hazards, and support improvements in land and resource management," said John Wheeler of the Geological Survey of Canada.

Unlike its predecessor, the map is not a static end-product. Because it was produced with digital technology, a digital database is planned by David Soller of the U.S. Geological Survey.

According to Soller, "Geoscientists for years to come will be able to access and analyze the data behind the map. This will stimulate additional research, expanding our body of knowledge at an increasingly rapid rate."

The map is available for purchase through the Geological Society of America.

TECTONICS

Quake Moved Sumatra By Only 20 Centimeters: Danish Scientists

Copenhagen (AFP) Jan 31, 2005
The Indonesian islands of Sumatra moved only 20 centimeters (7.9 inches) on average after last month's Asian earthquake and tsunami, and not dozens of meters as previously feared, media reported on Monday, quoting calculations by the Danish Space Center.

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