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The Rocks Don’t Lie,

But They Can Be Misunderstood

Allen F. Glazner, Dept. of Earth, Marine and Environmental Sciences, University of North Carolina, Chapel Hill, North Carolina, USA, afg@
unc.edu; Victor R. Baker, Dept. of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, Arizona, USA; John M. Bartley, Dept.
of Geology and Geophysics, University of Utah, Salt Lake City, Utah, USA; Kevin M. Bohacs, KMBohacs GEOconsulting LLC, Houston, Texas,
USA; Drew S. Coleman, Dept. of Earth, Marine and Environmental Sciences, University of North Carolina, Chapel Hill, North Carolina, USA

ABSTRACT familiar materials and processes at the nicely complements Chamberlin’s views.
Although the adage “the rocks don’t lie” Earth’s surface influences the interpretation Gilbert distinguished between investigators
is true—rocks are literal ground truth—their of features that formed at unfamiliar rates and theorists and viewed geology as investi-
message can be misinterpreted. More gener- and/or physical conditions. The rocks don’t gative. He argued that geologic hypotheses
ally, it is misguided to favor one form of lie, but preconceptions and human experi- rarely arise from theory, but rather through
inquiry, such as field observation, over oth- ence can cause us to misinterpret what they analogical reasoning inspired by the direct
ers, including laboratory analyses, physical reveal to us. study of nature (Gilbert, 1896). Gilbert’s
experiments, and mathematical or compu- emphasis on analogy and fruitfulness in the
tational simulations. This was recognized A Warning from the Distant Past origin of geological hypotheses has been
more than a century ago by T.C. Chamberlin, In his classic, oft-discussed paper, “The analyzed in detail by Baker (2014, 2017).
who warned against premature adherence to Method of Multiple Working Hypotheses,” Gilbert (1896, p. 12) stated an important
a “ruling theory,” and by G.K. Gilbert, who Chamberlin (1890) cautioned of the “blind- caveat regarding field investigations:
emphasized the investigative nature of ing influence” of a “ruling” or “premature” “However grand, however widely accepted,
geological reasoning. Geologic research theory. Because Chamberlin’s advocacy of however useful its conclusion, [no hypothe-
involves a search for fruitful, coherent, and keeping a nimble mind for one’s scientific sis] is so sure that it cannot be called in
causal hypotheses that are consistent with all work was written in the wordy, stilted, and question by a newly discovered fact. In the
the relevant evidence and tests provided by androcentric prose of his time, we have domain of the world’s knowledge there is
the natural world, and field observation is rewritten and condensed a key portion in no infallibility.”
perhaps the most fertile source of new geo- more modern language: The investigative nature of geological
logic hypotheses. Hypotheses that are con- The moment that you come up with an research has been emphasized recently by
sistent with other relevant evidence survive explanation for a phenomenon, you develop philosophers of science. Just as some crime
and are strengthened; those that conflict affection for your intellectual child, and scene evidence (e.g., fingerprints or DNA)
with relevant evidence must be either revised with time this grows ever stronger. You pro- can be highly conclusive for detective inves-
or discarded. ceed rapidly to acceptance of the theory, fol- tigations, so geological questions may be
lowed by unconscious selection of data that
fit and unconscious neglect of data that do most effectively resolved by what Cleland
INTRODUCTION not. Your mind lingers with pleasure on (2013) termed a “smoking gun.” Cleland
facts that confirm the theory and feels a cited as an example the bolide impact
The Critical Importance of Field natural coldness toward those that do not. hypothesis for the end-Cretaceous extinc-
You search instinctively for data that fit, for
Observations the mind is led by its desires. When these tions (Alvarez et al., 1980), where excess
Geology is largely a field-based science, biases set in, collection of data and their iridium and shocked quartz provide two bar-
and field evidence has long been given pri- interpretation are dominated by affection for rels. Cleland argued that the search for a
macy in interpretation of the Earth. This is the favored theory until you are convinced smoking gun works especially well for dis-
sometimes expressed as “the rocks don’t lie.” that it has been overwhelmingly confirmed. tinguishing among the multiple hypotheses
It then rises to a position of mind control,
Rocks do indeed record Earth’s history and guiding observation and interpretation— that commonly arise in historical natural
information about processes that link the lith- from a favored child into your master. sciences such as geology.
osphere, hydrosphere, atmosphere, and bio- When this last stage has been reached,
sphere. Understanding this record requires unless the theory happens to be correct, all Fieldwork is Challenging
proper interpretation of field observations. hope of progress is gone. The universe of observable features in
As field geologists, we have learned that geologic fieldwork is vast, so we must filter
the interpretation of field evidence is strongly The Nature of Geologic what we see to avoid paralysis. A soil scien-
shaped by what one has been taught as well Investigations tist might pay little attention to granite bed-
as by prevailing theories and reigning para- Gilbert (1886, 1896) described the meth- rock, whereas a granite petrologist would
digms. Moreover, one’s experience with ods of geological research in a way that likely do the opposite. This makes it difficult

GSA Today, v. 32, https://doi.org/10.1130/GSAT535A.1. CC-BY-NC.

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