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GMEG - Geophysics Unit of Menlo Park, CA- (GUMP)

 

Geophysics Unit of Menlo Park, CA (GUMP)

U.S. Geological Survey - Western Region - Geology and Geophysics

USGS Rock- and Paleo-magnetics Laboratory

History

paleomag building

The present Rock- and Paleo-magnetics Laboratory facility was constructed in the spring of 1996. It replaced the early 1940's temporary structure that formerly housed the laboratory.

 

 

Development of the Geomagnetic Polarity Reversal Timescale, critical to the acceptance of Plate Tectonics

During 1959-1966, the scientists of the rock magnetics laboratory in Menlo Park were involved in a race to prove that reverse-polarity magnetization in rocks was the result of global reversals of the geomagnetic field.  To prove their case, the scientists had to show that rocks of the same age throughout the world had the same magnetic polarity.  They collected samples from Alaska to Antarctica and from Hawaii to New Mexico.  In the laboratory, they measured the magnetic polarity of rock samples with a spinner magnetometer and determined the ages of samples with an argon mass spectrometer.  As more and more polarity-age pairs were gathered at this laboratory and elsewhere, a consistent pattern began to emerge, demonstrating that indeed the earth’s magnetic field had reversed polarity many times in the past.  Within a few years, the Geomagnetic Polarity Reversal Timescale was published.  When it was recognized that the polarity timescale was matched by magnetic patterns on the seafloor, the concepts of seafloor spreading and mobile continents became widely accepted.  This discovery about earth magnetism became the foundation for modern plate tectonic models that explain mountain building, the formation of ocean basins, and the distribution of continents.

In 1995, recognition of the fundamental scientific contributions made by Allan Cox, Richard Doell, and Brent Dalrymple from 1959 to 1966 led to listing of the Rock Magnetics Laboratory on the National Register of Historic Places (#94001647).  The original laboratory was located in a neglected storage building that previously was used as a laundry for Dibble Army Hospital during World War II.  Cox and Doell established their Rock Magnetics Laboratory in this “tarpaper shack” in 1959, soon after the USGS acquired the army site.  The nearly all-wood construction of the building was ideal for their purposes.  Construction of the new laboratory in 1996 required removal of the original building, the essence of which is preserved in an exhibit in Building 16.  A documentary video, “Secrets in Stone,” was also commissioned as part of the exhibit.  The 30-minute video chronicles events from the discovery of geomagnetic reversals to the acceptance of plate tectonics and explains the essential scientific principles in terms understandable to a general audience.  Colorful animations and interviews with some of the scientists involved in this scientific discovery bring the story to life for viewers.  The movie is available in DVD format; contact Jack Hillhouse to obtain a copy.

Visitors are welcome to visit the laboratory, view the historical exhibits, and see the video describing the research and events that led to the landmark designation.

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