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Geology 201
Fall 2010
Quiz 4 Study Guide
What is the sequence of discoveries from ~1945-1965 that led to plate tectonics?
How did seismology support the interpretation of three types of plate boundaries?
How did prevailing geological ideas influence people's reactions to the new global tectonics?
How did the new global tectonics influence subsequent geological studies?
Does the theory of plate tectonics fit in with uniformitarianism? Why or why not?
Which of the people covered in this section do you think was the most important in the
development of plate tectonics? Support your answer.
People
Alfred Wegener: German meteorologist, passionate champion of the hypothesis of continental
drift, amassed copious data in support but failed to provide an adequate and acceptable
mechanism, rejected by contemporaries, died in Greenland on an expedition to (in part) seek
more supporting data for CD
Arthur Holmes: English geologist, wrote Principles of Physical Geology (influential textbook
in mid 1900s), one of the first to suggest that convection of the "substratum" under the
continents and oceans could provide the missing mechanism for Wegener's continental drift:
upwelling beneath mid-ocean ridges and descent beneath oceanic trenches
Hugo Benioff: California geophysicist, had a knack for developing and improving instruments
to measure earthquakes, research career at Calteck, documented subducting slabs at trenches by
plotting depth of earthquake foci in various locations around the world, published his study in
1954 but Wadati had made similar though less detailed observations in 1928 - inclined lines of
foci under volcanic and island arcs are now known as Benioff-Wadati zones
Harry Hess: New York native, spent most of his career at Princeton U, studied gravity and
bathymetry of ocean floors, suggested that new ocean floor forms at mid-ocean ridges and
moves laterally away, uncertain enough of his hypothesis to call it "geopoetry" instead of a
rigorous scientific demonstration, the term "sea-floor spreading" was coined by a colleague
Allan Cox: California geophysicist, worked at US Geological Survey and Stanford U,
specialized in paleomagnetism, demonstrated that the Earth's magnetic field reverses itself from
time to time, unraveled the details of the geomagnetic reversal time scale
Fred Vine: English geophysicist, studied ophiolites and paleomagnetism, , explained magnetic
anomalies as the result of sea-floor spreading plus reversals of the magnetic field, hypothesis
confirmed by later studies at other ridges around the world
Geology 201
Fall 2010
Drummond Matthew: English geophysicist, research on the structure of the continental crust,
published the first detailed magnetic survey of a mid-ocean ridge, advisor to Vine
J. Tuzo Wilson: native of Canada, spent most of his academic career at the University of
Toronto, initially doubted that continents drifted but became a convert and advocate for drift,
showed that ridges and trenches could not explain all plate interactions, proposed a third type of
boundary called transform and marked by transform faults
Tanya Atwater: California geophysicist, long career at UC Berkeley emphasizing classroom
teaching and public outreach, expert on the plate tectonic history of the northeast Pacific Ocean
and western North America, studied the origin and growth of the San Andreas Fault system as
the Pacific-Farallon Ridge reached the subduction zone off the west coast of NA
Paul Silver: California geophysicist, researcher at the Carnegie Institute and Johns Hopkins
University, studies physics of earthquakes, structure of the lithosphere, and details of
subduction zones, wrote a summary paper on the Wilson Cycle (opening and closing of ocean
basins => reconstructing former supercontinents: Pangaea, Rodinia, Columbia, Kenorland, Ur)