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Science Tour - 3D/4D mapping of the San Andreas Fault Zone

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Example of 3D geologic interpretation: The diagram below shows a geologic cross section (interpretation) of the upper part of the earth's crust on an east-to-west transect across the Bartlett Springs Fault Zone in the Wilbur Hot Springs area, northern California. The trace of the cross section is shown on the geologic map, and the colors correspond to the map units on the geologic legend. The cross section illustrates the collective effort of observing mapable rock units and recording aspects of changes in their orientation from tectonic forces after the rocks formed. Information from surface observations are combined with information derived or inferred from the subsurface, such as gravity and magnetism geophysical mapping, deep well data (where available), and other methods to make and refine third-dimensional interpretations of the geology of a region. With the completion of regional mapping (and cross-section interpretation), data can now be modeled in a third dimension (3D) using new earth imaging systems.

Cross section showing an east-to-west slice of the earth's crust in the Wilbur Hot Springs area, California

Graphic provided by Robert McLaughlin; revised from:

McLaughlin, R. J., Ohlin, H. N., and Thormahlen, D. J., , 1990, Geologic map and structure sections of the Little Indian Valley - Wilbur Springs geothermal area, northern Coast Ranges, California: U.S. Geological Survey Miscellaneous Information Series Map, I-1706, scale: 1:24,000.

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