Great Geologists | 15
Key geological principals as set out
by Steno in 1669.
1: Principal of Superposition -
younger strata overlie older strata;
2: Principal of Original Horizontality
– sedimentary layers are originally
deposited flat (2a) and can
therefore be tilted by crustal
movements (2b);
3: Principal of Lateral Continuity
– layers of sedimentary rock are
continuous until they encounter
other solid bodies that block their
deposition or until they are acted
upon by agents after deposition.
as effectively synchronous and the
biblical flood seemed almost unbelievably
ancient. To suggest that fossils could be
so old was challenging — such were the
perceptions of the age of the Earth at that
time.
Having recognised how crystals and
shells grow progressively by the addition
of layers, in a leap of insight he applied
this concept to the strata of the Earth.
This is now known as the Principle
of Superposition — in a sequence of
sedimentary layers the bottom layer is the
oldest and those above are progressively
younger.
Steno also stated that water-deposited
sediments are laid down horizontally
and form continuous layers — the
Principals of Original Horizontality and
Lateral Continuity. Therefore, tilted or
discontinuous strata represented folding
or faulting movements within the crust,
features he observed within Tuscany.
Steno had shown that the rock record
and its fossil content could be used to
interpret a chronology. That is to say,
rocks represent a book waiting to be read
REFERENCES
This essay has drawn upon information
from the following sources:
Adams, F.D. 1938. The Birth and
Development of the Geological Sciences.
Williams & Wilkins.
Cutler, A. 2003. The Seashell on the
Mountaintop. William Heinemann Ltd,
240pp.
Cutler, A. 2007. Nicolaus Steno: unlocking
the Earth’s geological past. In: Huxley,
R. (ed.) The Great Naturalists. Thames &
Hudson, 86-91.
that can reveal the history of our planet.
This was a fundamental contribution to
science. Such principles paved the way
for James Hutton over 100 years later to
appreciate the long age of the Earth and
for William Smith, Georges Cuvier and
others to begin to classify the strata of the
Earth and initiate the unravelling of Earth’s
history. Gohau, G. 1990. A History of Geology.
Rutgers University Press. 259pp.
In 1669, Steno was obliged to end his
geological studies with a return to medical
work in Copenhagen. This coincided
with his conversion from Lutheranism to
Catholicism and subsequently immersing
himself in theology. He never returned to
geology. Rudwick, M.J.S. 1972. The Meaning of
Fossils. The University of Chicago Press,
287pp.
In 1675 he took holy orders and became
a priest in 1677. He became a bishop
tending to the small Catholic population
in northern Germany. He took a vow
of poverty and the rigors of this life
destroyed his health, bringing about his
death in 1686 at the relatively young age
of 48. His legacy is the foundation of the
sciences of paleontology and geology and
critical insights into how the human body
works. For his religious endeavors, he was
beatified by Pope John Paul II in 1988. Scherz, G. Undated. Niels Steensen. Royal
Danish Ministry of Foreign Affairs. 95pp.
Gould, S.J. 1983. Hen’s Teeth and Horse’s
Toes. W.W. Norton & Company, Inc.,
413pp.
Oldroyd, D.R. 1996. Thinking About the
Earth. The Athlone Press, 410pp.
Rudwick, M.J.S. 2014. Earth’s Deep
History. The University of Chicago Press,
360pp.
http://nielssteensen.dk/