Plate Tectonics and People

Richard Doell

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<div><span style="color: rgb(165, 42, 42);">By Sharon Dykhoff</span></div>
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<p><span style="color: rgb(0, 0, 0);">"<em>Your pioneering work on the magnetic properties of rocks, your careful choice of signficant rocks for study, [and] your demonstration of the reality of the reversals of the main magnetic field of the earth...have earned you a permanent place in the annals of earth science." </em>~ Nobel Laureate Polykarp Kusch, presenting the Vetlesen Prize to Richard Doell and Allan Cox, 1971.  </span></p>
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<div class="img-center"><img alt="Richard Doell" src="/earth520/sites/" style="width: 300px; height: 320px;">
<div class="img-caption">Photo 1.  Richard R. Doell</div>
<div class="img-caption">1923-2008</div>
<div class="img-credit">Image source: <em>Richard R. Doell: A Biographical Memoir </em>by G. Brent Dalrymple</div>
<h2><span style="color: rgb(165, 42, 42);">Biographical Information</span></h2>
<h3><span style="color: rgb(0, 0, 0);">Education</span></h3>
<p>In 1952, a geophysics student at the University of California-Berkeley named Richard R. Doell attended a seminar on the new field of paleomagnetism.  Paleomagnetism includes the study of iron-bearing minerals in molten rock that are magnetized in the direction of the Earth's magnetic field when the lava cools and hardens.  The idea that rocks could preserve a magnetic memory of the direction of the Earth's magnetic field fascinated Doell.  After earning his B.A. in geophysics, he decided to stay on at UC-Berkeley and do graduate work with the volcanologist who taught the seminar, Dr. John Verhoogen. </p>
<p>Doell did his thesis work on paleomagnetism in sedimentary rocks in the Grand Canyon and the Neroly Formation near Livermore, California.  He found, however, that sedimentary rocks did not produce reliable information on magnetic field orientation, so he switched his study to volcanic rocks.  About this time he met Allan Cox, a geology student who shared his interest in paleomagnetism and who would become his colleague and lifelong friend (Dalrymple, 2016).</p>
<h3><span style="color: rgb(0, 0, 0);">Early Career</span></h3>
<p>After earning his Ph.D. in geophysics in 1955, Doell worked with J. Tuzo Wilson at the University of Toronto where he built another paleomagnetics laboratory.  The next year he was offered an assistant professorship at the Massachussetts Institute of Technology where he taught geophysics and a course on the new topic of geomagnetic pole reversals.  In 1959, he was diagnosed with melanoma and given only a few years to live, so he and his wife moved back to California to be near their families.  Fortunately, the prognosis proved to be wrong, and Doell was able to continue is work on paleomagnetism at the U.S. Geological Survey with his old friend, Allan Cox (Dalrymple, 2016).</p>
<p>Again, Doell was faced with the need to build a laboratory.  At the USGS facility in Menlo Park, Doell and Cox converted an old wood and concrete building that had been used as a World War II rehabilitation hospital into their workspace.  This building, which they referred to as their "tarpaper shack," was well-suited for their work because it was made of nonmagnetic materials.  Doell became the project chief of the new Rock Magnetics Laboratory at Menlo Park.  With USGS funding, he was able to put together a first-rate lab.  Again, he designed and helped build many of the instruments that he and Cox would use to make significant contributions to the understanding of geomagnetic field reversals and, eventually, the new theory of plate tectonics (Dalrymple, 2016)</p>
<div class="img-center"><img alt="photo of USGS tarpaper shacks in Menlo Park, CA circa 1965" src="/earth520/sites/
<div class="img-caption">Photo 2.  USGS Tarpaper shacks in Menlo Park, California, circa 1965. The Rock Magnetics Laboratory building was designated as a National Historic Landmark in 1995, but it was demolished in 1996 after documentation.</div>
<div class="img-credit">Image source: USGS</div>
<h2><span style="color: rgb(165, 42, 42);">Scientific Contributions to Plate Tectonics</span></h2>
<p>While waiting to occupy their new lab, Doell and Cox wrote a comprehensive literature review for the Geological Society of America Bulletin on the theory, methods, and data available on paleomagnetism (Cox and Doell, 1960).  It was the first of many productive collaborations.</p>
<h3>Dipole Theory of the Earth's Magnetic Field</h3>
<p>In their early experiments, Doell and Cox used volcanic rocks to test the dipole theory of the Earth's magnetic field.  This was the idea that the Earth's magnetic field is shaped as if a giant bar magnet was inserted through the Earth's center with the lines of force directed toward or away from the center except at the Equator.  They studied the magnetic memory preserved in volcanic rocks containing iron and titanium.  At high temperatures, these metals are nonmagnetic, but as they cool to a critical point known as the Curie temperature, they become magnetic.  The orientation of the tiny crystals is visible under a microscope.  As the rocks cool, the magnetization is at first "soft," like a metal that has been weakly magnetized.  As they cool further, the magnetization becomes "hard," like a permanent magnet.  Softly magnetized particles in rock can also be acquired after the rock forms, such as by lightning strikes or chemical changes.  To be certain that the samples provided a record of the past geomagnetic field, Doell invented an ingenious device he called a "magnetic washing machine."  In a four-axis tumbler, rocks were subjected to alternating-current to remove any soft magnetism while the sample's hard magnetism was retained (Cox, Dalrymple, & Doell, 1967).</p>
<div class="img-center"><img alt="photo of three-axis magnetic rock washing machine" src="/earth520/sites/
<div class="img-caption">Photo 3.  Three-axis magnetic washing machine. Rock samples were subjected to alternating-current while rotating on 3 axes, negating the soft magnetism while preserving the hard magnetism.</div>
<div class="img-credit">Image source: Cox, Dalrymple, & Doell, 1967.</div>
<h3><span style="color: rgb(0, 0, 0);">Geomagnetic Polarity Reversals</span></h3>
<p>These were the days of early debate on the theory of plate tectonics, and scientists began looking for evidence of past plate movments in the new field of paleomagnetism.  Doell and Cox began to focus their research on reversals of the Earth's magnetic field.  Curiously, some volcanic rocks displayed magnetic orientation 180 degrees from "normal" orientation.  Well-respected scientists had proposed that these magnetic reversals were caused by "self-reversal" of magnetic particles in the rocks.  A second explanation was that the reversals had been caused by a polarity change of the magnetic field of the Earth itself when the rock was formed.  This explanation seemed far-fetched, in part because the source of the Earth's magnetic field was not well-understood.  This did not deter Doell and Cox from trying to find an answer.  They ran laboratory experiments to heat and cool rocks in known magnetic fields to see if they would self-reverse.  They found that less than 1% of their samples self-reversed (Cox, Dalrymple, & Doell, 1967). </p>
<p>However, other mechanisms for self-reversal could not be reproduced in the lab or in short periods of time.  So Doell and Cox looked for correlations between mineral properties and magnetic polarity.  They sampled young volcanic rocks from a wide range of geographic areas - Iceland, Hawaii, Alaska, the Galapagos Islands, Antarctica, and the western U.S.  If rocks self-reversed, they expected to find random scattering of polarities.  If the reversals were worldwide, they expected to find polarities correlating to definite time periods (Dalrymple, 2016).  To find an answer, Doell and Cox needed a way to measure the ages of young volcanic rocks. </p>
<p>Sitting around a campfire at a conference in 1961, Doell and Cox solicited the expertise of G. Brent Dalrymple.  Dalrymple was one of the few people in the world who was able to detemine the ages of young volcanic rocks using a very precise mass spectrometer and the potassium-argon (K-Ar) method.  Once again, equipment needed to be built.  Doell and Dalrymple bought a precise gas mass spectrometer, added the electronics and magnet, and built a table in Doell's garage to hold the gas extraction lines (Dalrymple, 2016).</p>
<p>The K-Ar method was an ideal radioactive clock for their work because it could be applied to rocks that formed in a range of several thousand to a few million years ago.  The potassium-40 isotope decays at a known, constant rate to argon-40, which is an inert gas, meaning it forms no compounds.  The Ar-40 is trapped in the crystalline structure of the rocks.  Since argon will not accumulate in molten rock,  it can be used to calculate the time at which the rock solidified. The amount of Ar-40 compared to the amount of K-40 determines the length of time since the decay began (Cox, Dalrymple, & Doell, 1967).</p>
<div class="img-center"><img alt="cox, doell, and dalrymple at work in the rock mag lab 1965 (photo)" src="/earth520/sites/
<div class="img-caption">Photo 4.  USGS photo of Allan Cox (seated), Richard Doell, and Brent Dalrymple in the Rock Magnetics Laboratory, circa 1965.  </div>
<div class="img-credit">Image source: De Vries, 1995.</div>
<h3><span style="color: rgb(0, 0, 0);">Geomagnetic Polarity Time Scales</span></h3>
<p>They found that the ages of magnetically normal and magnetically reversed rocks were grouped into distinct sequences.  This confirmed that the polarity reversals were field reversals and not self-reversals.  Between 1963 and 1966, the men published seven geomagnetic polarity time scales, refining each one as more data was available.  Their time scales showed four long periods of polarity over the past 3.6 million years (which they called geomagnetic polarity epochs, naming them after pioneers in paleomagnetism).  The epochs (now called "chrons") were interrupted by shorter reversal events, which they named after the geographic location of the rock samples.  The polarity events are notable because they affirmed the irregular nature of the magnetic reversals (Cox, Dalrymple, & Doell, 1967).</p>
<div class="img-center"><img alt="magnetic polarities of rocks and magnetic declination timescale" src="/earth520/sites/ style="width: 400px; height: 277px;">
<div class="img-caption">Figure 1.  Magnetic polarities of 64 volcanic rocks and their potassium-argon ages.  Figure from Cox, Doell, & Dalrymple's 1964 paper in <em>Science. </em></div>
<div class="img-credit">Image source: Cox, Doell, & Dalrymple, 1964.</div>
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<div class="img-center"><img alt="timescale for earth's magnetic field reversals from paleomag data" src="/earth520/sites/
<div class="img-caption">Figure 2.  Time scale for reversals of Earth's magnetic field based on paleomagnetic data and radiometric ages for nearly 100 volcanic formations. Figure from Cox, Dalrymple, & Doell's 1967 <em>Scientific American </em>article.</div>
<div class="img-credit">Image source: Cox, Dalrymple, & Doell.</div>
<h3><span style="color: rgb(0, 0, 0);">Sea Floor Spreading Confirmed</span></h3>
<p>The discovery of the Jaramillo polarity event, described in Doell and Dalrymple's 1966 paper, was particularly important because it provided the final piece of evidence for the theory of sea floor spreading.  Harry Hess of Princeton had proposed in 1962 that the sea floor was spreading outward from the mid-ocean ridges, but he had no empirical evidence to support his idea.  Magnetic surveys of the ocean floor revealed a striped pattern of polar reversals.  However this same pattern was not readily evident on the continents.  Doell, Cox, and Dalrymple's polarity time scales of land-based samples came close to matching the sea floor pattern, but not quite exactly.  When the Jaramillo event was added to the time scale, the magnetic stripes on either side of the mid-ocean ridge matched the land-based scale exactly.  For this reason, the geomagnetic reversal time scales published by Doell, Cox, and Dalrymple have been called the Rosetta Stone of the theory of plate tectonics.</p>
<div class="img-center"><img alt="schematic of geomagnetic reversal pattern at a mid ocean ridge" src="/earth520/sites/
<div class="img-caption">Figure 3.  Geomagnetic reversal time scale, including the Jaramillo event, and its correlation with normal and reversed magnetic strips on the ocean floor at the mid-ocean ridge. </div>
<div class="img-caption"><em>Image source:  Dalrymple, 2016.</em></div>
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<p>In recognition of their work on the reversal time scale, Doell and Cox were elected to the National Academy of Sciences in 1969 and they were awarded the prestigous Vetlesen Prize for achievement in earth sciences in 1971, along with Keith Runcorn of Great Britain.</p>
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<p><img alt="receiving the vetlesen prize in 1971 (photo)" src="/earth520/sites/
<p><strong>Photo 5.  Cox, Doell, and Runcorn receive the Vetlesen prize in 1971 for their contributions to the theory of plate tectonics.</strong></p>
<div class="img-credit">Image source: Dalrymple, 2016. </div>
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<h2><span style="color: rgb(165, 42, 42);">Other Scientific Contributions</span></h2>
<p>Doell was a NASA principal investigator for Apollo 11-13 missions.  He designed a flux-gate magnetic gradiometer to be used in the Lunar Receiving Laboratory for estimating induced and remament magnetism in lunar rocks.  With Dalrymple, he also designed an instrument to measure thermoluminescence of Apollo 11 and 12 lunar soil samples to find out how frequently the soils had been disturbed by meteorite impacts (Dalrymple, 2016). </p>
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<h2><span style="color: rgb(165, 42, 42);">Other Cool Stuff You Should Know</span></h2>
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<h3><span style="color: rgb(0, 0, 0);">If at first you don't succeed, try, try again . . .</span></h3>
<p>In high school, Doell showed an aptitude for mathematics and drafting.  After graduating in 1940, he enrolled at UCLA.  More interested in socializing than his studies, Doell dropped out with the intention of becoming an Navy aviator.  He was turned away for medical reasons, but in 1942 he was drafted by the U.S. Army and he served in Europe in World War II.  After his discharge in 1945, he enrolled at the University of California-Berkeley to study physics.  Again, poor study habits prevailed, and he left the university to work as a draftsman.  His work for United Geophysical sparked an interest in geology, so he reapplied to UC-Berkeley.  During his re-admission interview,  geophysics professor Peter Byerly remarked, " have a good job; keep it," (Dalrymple, 2016).  However, Doell was not dissuaded, and he declared a major in geophysics.  The third time was a charm. </p>
<p>In 1978 Doell retired from the USGS to work and sail on his 38-foot sailboat, the MUAV.  With family and friends, he accomplished many sailing trips along the west and east coast of the United States, as well as Alaska, French Polynesia, the Galapagos Islands, Iceland, 23 countries in Europe, and the Soviet Union.  He died in 2008 after an illness. </p>
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<h2><span style="color: rgb(165, 42, 42);">Want to know more?</span></h2>
<h3><span style="color: rgb(0, 0, 0);"><em>The Road to Jaramillo: Critical Years of the Revolution in Earth Science </em> by William Glenn</span></h3>
<p><em>The Road to Jaramillo</em> traces the history of scientific research and discoveries in the 1960s and 1970s that lead to the acceptance of the theory of plate tectonics. </p>
<p>"'Serendipity in science' is one of the important messages in this book; another is that major advances in science are achievable only if the research environment encourages the exercise of human curiosity with undue emphasis on immediate applications of specific increments of the research.  This book is an important record of an episode in earth science research, and a signficant commentary on how advances in any science are accomplished." - Robert Wallace, <em>Earth-Science Reviews, </em>June 1984. </p>
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<h3><span style="color: rgb(0, 0, 0);"><em>Secrets in Stone: The Role of Paleomagnetism in the Evolution of Plate Tectonic Theory</em></span></h3>
<li>2004 lecture introducing the film <em>Secrets in Stone</em> at the U.S. Geological Survey in Menlo Park, California: <a href="">http://onlin...
<li>USGS video <em>Secrets in Stone</em> (35 minutes):  <a href=""></a>...
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<h2><span style="color: rgb(165, 42, 42);">Bibliography</span></h2>
<p>Cox, A., & Doell, R. R. (1960). Review Of Paleomagnetism. <em>Geological Society of America Bulletin,</em> <em>71</em>(6), 645. doi:10.1130/0016-7606(1960)71[645:rop];2</p>
<p>Cox, A., Dalrymple, G. B., & Doell, R. R. (1967). Reversals of the Earth's Magnetic Field. <em>Scientific American,</em> <em>216</em>(2), 44-54. doi:10.1038/scientificamerican0267-44</p>
<p>Cox, A., Doell, R. R., & Dalrymple, G. B. (1964). Reversals of the Earth's Magnetic Field. <em>Science,</em> <em>144</em>(3626), 1537-1543. doi:10.1126/science.144.3626.1537</p>
<p>Dalrymple, G. B. (2016). Richard R. Doell 1923-2008 Biographical Memoirs. National Academy of Sciences. Retrieved September 10, 2016, from <a href=" </a></p>
<p>Dalrymple, G., Cox, A., Doell, R. R., & Grommé, C. (1967). Pliocene geomagnetic polarity epochs. <em>Earth and Planetary Science Letters,</em> <em>2</em>(3), 163-173. doi:10.1016/0012-821x(67)90122-7</p>
<p>De Vries, D.G. (1995). 32. Scientists Allan Cox (seated), Richard Doell, and Brent Dalrymple at control panel, about 1965. U.S. Geological Survey, Rock Magnetics Laboratory, 345 Middlefield Road, Menlo Park, San Mateo County, CA. Retrieved September 11, 2016, from <a href="">http://...
<p>Glen, W. (1982). <em>The road to Jaramillo: Critical years of the revolution in earth science</em>. Stanford, CA: Stanford University Press.</p>
<p>Hillhouse, J., & Gordon, L. (Directors). (2004, July 29). <em>Western Region - Monthly Evening Lecture Series</em> [Video file]. Retrieved September 11, 2016, from <a href="">http://onlin...
<p>Hough, S. E. (2002). Plate tectonics revolution. In <em>Earthshaking science: What we know (and don't know) about earthquakes</em> (pp. 1-12). Princeton, NJ: Princeton University Press.</p>
<p><em>Secrets in Stone</em> [Video file]. (n.d.). Retrieved September 11, 2016, from <a href=""></a>...
<p>USGS. (n.d.) Tarpaper shacks in Menlo Park, California. Image retrieved September 11, 2016, from <a href="
<p>Wallace, R.E. (1984). The road to Jaramillo: Critical years of the revolution in earth science. <em>Earth-Science Reviews, 20</em>(3), 262-263. doi:10.1016/0012-8252(84)90020-5</p>
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