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Gaia concept on a geochemist, and Garrels was one of the few
willing to listen. Lovelock considered the global geochemical
cycling models “sterile,” without adequate accommodation for the
interactions with living organisms. Garrels argued that the biota
were implicit in aspects of the model (e.g., in the burial of organic
matter that created a net flux of oxygen to the atmosphere). But
Lovelock was looking for more, for regulatory mechanisms (feed-
backs) that recognized the importance of organisms in control-
ling what the geochemists were treating as largely inorganic
processes (e.g., chemical weathering). The ensuing decades have
witnessed an explosion of research on biotic influences on
“geologic” processes.
Garrels’ understanding of and concern for the environment was
expressed in a seminal publication with Mackenzie and Garrels’
second wife, Cynthia A. Hunt (Garrels et al., 1975) that presaged
our current realization that we live in the “Anthropocene,” an era
of geological relevance in which humans have modified the envi-
ronment at a global scale. He pondered the “world without us,”
wondering how long it would take to erase the presence of
mankind on the planet. Among other unpublished observations
he made in his later years were the correspondence between the
age of sidewalks and the extent of their re-carbonation through
reaction with carbonic acid in rainwater, and of the variety of
minerals precipitated on copper roofs and how they reflected the
regional deposition of various pollutants. Mason jar experiments
aimed at determining siderite solubility and copper-sulfate-
chloride solution interactions with biogenic calcite moved with
his last student, Terri Woods, to East Carolina University, where
they served as the basis for student research.
Garrels had diverse interests. He was an athlete who briefly
held the world masters records in the high jump and triple jump;
he was an avid tennis player; and he favored ping-pong over
extended discussions of science with his students if forced to
choose (although both could be conducted simultaneously, on
Fridays with beer in hand). He developed an algorithm to calcu-
late how many gin and tonics one deserved after a swim in the
ocean, depending on the strength and direction of the tide (it
turned out to be an exponential function; Berner, 1992). And he
was a poet. His “Cycle of P” has been reprinted often (see
https://en.wikipedia.org/wiki/Robert_Garrels), but less well
known is a shorter poem:
Geology – GSA Bulletin – Geosphere – Lithosphere
Special Papers – Memoirs – Field Guides – Reviews in Engineering Geology
The P Song
Pollutia
Cycle me, cycle me, you know where
Into the oceans and through the air
And if you don’t cycle me in the right place
I’ll weed up your rivers and eutroph your lakes.
Bob Garrels enjoyed life. He valued collaboration and compan-
ionship, and he was curious and imaginative. He had a great sense
of humor, he was fair and humble, and he was surprisingly
approachable for a scientist of his stature. I recall a group of us as
graduate students approaching him at the beginning of TGIF and
timidly alerting him to the fact that we had discovered an error in
a classic paper. Garrels response was “oh, that’s too bad—anyone
want to play ping-pong?”
Garrels was truly a rock star, and his legacy exists in the creative
way we view the operation of Earth as a system today.
REFERENCES CITED
Berner, R.A., 1992, Robert Minard Garrels: A biographical memoir:
Washington, D.C., The National Academies Press, p. 195–212,
http://www.nap.edu/read/2037/chapter/11#206.
Berner, R.A., Lasaga, A.C., and Garrels, R.M., 1983, The carbonate-silicate
geochemical cycle and its effect on atmospheric carbon dioxide over the
past 100 million years: American Journal of Science, v. 253, p. 641–683.
Garrels, R.M., and Mackenzie, F.T., 1971, Evolution of Sedimentary Rocks:
New York, W.W. Norton, 397 p.
Garrels, R.M., Mackenzie, F.T., and Hunt, C., 1975, Chemical Cycles and the
Global Environment: Assessing Human Influences: Los Altos, California,
William Kaufmann Inc., 206 p.
Krumbein, W.C., and Garrels, R.M., 1952, Origin and classification of chemical
sediments in terms of pH and oxidation-reduction potentials: The Journal
of Geology, v. 60, no. 1, p. 1–33.
Sloss, L.L., and Berner, R.A., 1989, Memorial to Robert M. Garrels, 1916–1988:
Boulder, Colorado, Geological Society of America Memorials, v. 20,
p. 5–10.
The “Rock Stars” series is produced by GSA’s History and
Philosophy of Geology Division.
GSA TODAY | www.geosociety.org/gsatoday
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