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190th Anniversary of the Birth of Eduard

Suess, the Father of Modern Global Geology

A.M. Celâl Şengör, ITU Faculty of Mines and the Eurasia Institute of Earth Sciences, Ayazağa 34469 Istanbul, Turkey, sengor@itu.edu.tr

INTRODUCTION made continuing in the technical univer-
When rational speculation began more than two-and-a-half sity undesirable. Suess applied to the
millennia ago on the eastern shores of the Aegean with a view to Hofmineralienkabinett, the predecessor
explaining observations made on natural objects and events, geol- of the present magnificent Natural
ogy was born. For nearly two millennia, mankind had to make do History Museum in Vienna, as a volun-
with what could be seen on the surface of the earth. Despite this teer paleontologist and showed such
severe limitation, some very ingenious theories were put forward remarkable ability that he became perma-
about the behavior of our planet: It was realized that mountains rose nently employed with full salary (by that
from the sea and volcanoes and earthquakes were somehow related time he had already discovered three new
to the heat within our globe and they seemed associated with moun- fossil species: one graptolite and two
tain-building. This state of affairs changed dramatically when brachiopods). In 1857, he switched to the
Descartes introduced the concept of a bed (i.e., a layer) in 1644. Figure 1. Eduard Suess University of Vienna because he thought
Descartes’ concept was purely imaginary, but it triggered a revolu- (1831–1914). Public domain. the way geology was being taught in
tion in the hands of Nicolaus Steno in 1667 and 1669, when the ori- Austria was unsatisfactory. He wanted to
gin of beds were recognized to be sedimentation, fossils former show that geology was more than just minerals and rocks and fossils
inhabitants of sedimentary basins, and the haphazard orientations with some mining applications.
of bedded sequences a result of subsequent deformation. This gave a As a professor, Suess was very keen on field observation, both
great impetus to attempts to explain the history of the earth in terms with his students and by himself. At the beginning of his teaching
of sedimentary sequences until it was realized that not all rocks career two things surprised him: the Tertiary stratigraphy observed
were products of sedimentation. The next great step in the history of in the Vienna basin could be extended, in the same sequence and at
geology was taken by James Hutton in Scotland. Hutton argued that similar elevations above sea-level, all the way east to the region of
rocks rising as melts from the interior caused deformation of the the Aral Sea and west almost as far as Switzerland. This inspired
sedimentary layers and that this process had been going on since as him to question the theory of independent vertical motions of conti-
long ago as our observations could decipher. He further pointed out nents to explain regional unconformities, at the time advocated by
that no miracles are needed to explain the course of the geological Sir Charles Lyell and his followers. The persistence of the unde-
history of the earth: The present-day phenomena we observe daily formed stratigraphy for such immense distances, Suess thought,
provided sufficient explanation of everything one could discover in could not be explained by differential vertical motions. He thought
the geological record. it must have been the global sea level that was changing (he called
Hutton’s theory coincided in time with the rise of biostratigraphy them eustatic movements in 1888), and to accomplish that the ocean
that enabled geologists to erect a calendar of events in the earth’s basins had to have changed their capacity throughout geological
past, albeit without being able to put numbers of years onto it. These time. But how did they do it?
two developments gave geology an immense stimulus, and strati- Another surprising field observation helped him to think of a
graphic geology was able to erect a timetable for earth history by mechanism. He found that an anticlinal structure beginning in
the middle of the nineteenth century, which we still use. All kinds western Switzerland and continuing all the way to the western
of theories were advanced to explain the planet’s past, and their Carpathians accompanied the Alpine front. He had earlier seen,
inventors picked and chose those observations agreeable to their during a mapping exercise in the Alps, that the Alpine “central mas-
particular hypothesis. With Lyell’s insistence that there never had sifs” consisting of granites and gneisses and at the time held respon-
been any global events in the past, geology became detailed but sible for raising the Alpine edifice as intrusive masses, could not
parochial. The spectacular failure of a few attempts at global geol- have done that, because their erosional debris was contained in the
ogy encouraged this tendency to be local. It seemed that geology, early Mesozoic sequences. It was clear that they had been deformed
while able to explain local observations, lacked a method with together with the younger sedimentary cover. Suess realized that not
which earth as a whole could be understood. vertical, magma-driven, uplift, but lateral shortening was respon-
sible for the origin of the Alps. His excursions in Italy further
SUESS, THE GEOLOGIST showed him that while shortening was going on in the external
This all changed when a man, born in London on 20 August 1831 parts of the Apennines, stretching and subsidence, accompanied by
to Austrian parents who had been residing there temporarily for active volcanism, dominated the internal parts, there creating the
business reasons, stepped into the picture (Fig 1). Multilingual from Tyrrhenian Sea. He compared this with the Carpathians and the
childhood, Suess developed an interest in geology while visiting the Pannonian basin behind them and concluded that it was the motion
“Fatherland Museum” in Prague as a 19-year-old, where there was a of upper lithospheric slabs that was responsible both for the exten-
collection of fossils. His family wished him to become an engineer sion and the coeval shortening. This was contrary to all that was
to continue the family business, but the political affairs of 1848 claimed about the behavior of the planet in the early seventies of the

26 GSA Today | November 2021