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"A Tapestry of Time and Terrain"
"Through computer processing and enhancement, we have brought together two existing images of the the Nation's lower 48 states into a single digital tapestry. Woven into the fabric of this new map are data from previous U.S. Geological Survey (USGS) maps that depict the topography and geology of the United States. The resulting composite is the most detailed and accurate portrait of the U.S. land surface and the ages of its underlying rock formations yet displayed in the same image. The new map resembles traditional 3-D perspective drawings of landscapes with the addition of a fourth dimension, geologic time, which is shown in color. In mutually enhancing the landscape and its underlying temporal structure, this digital tapestry outlines the geologic story of continental collision and break-up, mountain-building, river erosion and deposition, ice-cap glaciation, volcanism, and other events and processes that have shaped the region over the last 2.6 billion years." |
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