The Rock Magnetics Laboratory, located
at the United States Geological Survey in Menlo Park, was the
site of research by Richard Doell, Allan Cox, and Brent Dalrymple.
Their research established and dated reversals in the Earth's
magnetic field, and helped to confirm the theory of plate tectonics,
the major revolution in earth science in the twentieth century.
The Rock Magnetics Laboratory was a one-story,
barracks style temporary building, originally part of a World
War II military hospital. The walls were covered by rolled asphalt
material, and the building was set on a concrete slab. It became
known as the "tarpaper shack;" its lack of metal supports
made it ideally suited for the needs of the lab.
At this lab Doell, Cox and Dalrymple
demonstrated, contrary to the prevailing scientific opinion
of the time, that the earth's magnetic field had reversed its
direction at intervals on the order of tens of thousands to
a few million years. As a result, they developed the geomagnetic
reversal time scale for the last 5 million years. The time scale
developed here, between 1957 and 1966, was the key to the interpretation
of striped magnetic anomalies on the deep ocean floor that were
being discovered and mapped at the same time by marine geophysicists.
This interpretation of the striped magnetic patterns and the
use of the geomagnetic polarity time scale led to the rapid
acceptance of sea floor spreading and the development of plate
tectonics. For their paleomagnetic research, Cox and Doell were
awarded geology's highest honor, the Vetlesen Prize, in 1971.
of the laboratory, showing some of the original instrumentation
National Historic Landmarks photograph, by Louis S. Wall,1994.
The building, retaining its original
research equipment, was designated a National Historic Landmark
on October 12, 1994. Originally constructed as a temporary building,
however, it was in extremely poor condition and was finally
demolished in 1997. Prior to demolition, Historic American Engineering
Record documentation was collected and the historic instrumentation
was relocated to a new laboratory building, now called the Paleomagnetics
The Landmark designation of the Rock
Magnetics Laboratory was withdrawn on March 8, 1999, and the
property was removed from the National Register of Historic