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MURCHISON, RODERICK IMPEY (b. Tarradale,
Ross and Cromarty, Scotland, 19 February 1792;
d. London, England, 22 October 1871), geology.
devoted himself chiefly to fox hunting. A chance
acquaintance with Humphry Davy turned his attention
toward science, however, and in 1824 he settled in
London and attended lectures at the Royal Institution.
Encouraged by his wife, Murchison soon focused his
interests on geology, chiefly through the influence of
William Buckland; he was elected a fellow of the
Geological Society of London in 1825 and of the
Royal Society in 1826. With the advantages of a
private income, he was able thereafter to devote
himself entirely to science.
Taking as a model the stratigraphical handbook of
W. D. Conybeare and W. Phillips (1822), Murchison
began the long series of geological studies which
brought him worldwide fame and recognition. Almost
every summer, for over twenty years, he undertook
long and often arduous journeys in search of new
successions of strata which would help to bring order
to the reconstruction of the history of the earth. He
entered geology during the first great period of
stratigraphical research, and stratigraphy remained
his chief area of interest. He was not a theoretician
and generally delegated the paleontological parts of
his work to others, but he was an excellent observer
with a flair for grasping the major features of an area
from a few rapid traverses.
Some of his earliest work convinced Murchison of
the superiority of fossils over lithology as criteria of
geological age: in 1826 he showed that the fauna and
flora of the isolated coalfield of Brora in northeastern
Scotland indicated it to be of the same age as the
English Oolites (that is, Jurassic), although the rock
types resembled the Coal Measures (that is,
Carboniferous). In 1828 he accompanied Charles
Lyell through the celebrated volcanic districts of the
Massif Central into northern Italy, and their joint
papers suggest that Murchison was at this time much
influenced by Lyell's theoretical views. His subsequent
work in the Alpine region, some of it in the company
of Adam Sedgwick, included an attempt to show the
continuity of the Secondary and Tertiary strata; but,
at the same time, firsthand experience of the vast scale
of folding and faulting in the Alps led Murchison
toward an increasing catastrophist emphasis on the
role of occasional episodes of drastic disturbance in
the crust of the earth.
During these first years of research Murchison's
travels brought him into contact with most of the
leading geologists on the Continent, and his position
as secretary (from 1827) of the Geological Society
made him equally well known in Britain. In 1831 he
was elected president of the Geological Society (he held
office until 1833, and again from 1841 to 1843), and
in the same year began his most important research.
At this time the major features of the stratigraphical
succession had been clarified down to the Old Red
Sandstone underlying the Carboniferous rocks, but
below that was what Murchison called “interminable
grauwacke”--rocks containing few fossils, in which no
uniform sequence had been detected. It was widely
doubted whether the method of correlation by fossils
would even be applicable to these ancient Transition
strata, yet in them--if anywhere--lay the possibility
of finding evidence for the origin of life itself.
Acting on a hint of Buckland's, Murchison was
fortunate to find in the Welsh borderland an area in
which there was a conformable sequence downward
from the Old Red Sandstone into Transition strata
with abundant fossils. He gave a preliminary report
of his work at the first meeting (1831) of the British
Association for the Advancement of Science; and in
1835, after further fieldwork, he named the strata
Silurian after the Silures, a Romano-British tribe that
had lived in the region.
The Silurian constituted a major system of strata
with a highly distinctive fauna, notable for an abundance
of invertebrates and for the complete absence,
except in the youngest strata, of any remains of
vertebrates or land plants. It thus seemed to
Murchison to mark a major period in the progressive
history of life on earth. Even before he had completed
his great monographic account The Silurian System
(1839), its validity had been rapidly recognized by
geologists in many other parts of the world. The
striking uniformity of the Silurian fauna, in contrast
with the highly differentiated faunal provinces of the
present day, was taken by Murchison to underline
the limitations of Lyell's uniformitarian approach, and
was attributed by him to the greater climatic
uniformity of the globe in Silurian times, a result of
the greater influence of conducted heat from the still
incandescent interior of the earth.
Murchison was well aware of the vast economic
implications of his delineation of a Silurian system.
If the Silurian period had truly predated the establishment
of terrestrial vegetation, the recognition of
Silurian fossils in any part of the world would
reliably indicate a base line beneath which it was
pointless to search for coal: this would save much
useless expenditure and also help to assess more
accurately the possible reserves of undiscovered coal.
A report by Henry de la Beche of coal plants in the
“grauwacke” of Devonshire (1834) therefore seemed
to Murchison to be a very serious anomaly, and he
devoted several years to an attempt to explain it away.
He and Sedgwick discovered first that the fossil plants
were in fact in strata of Coal Measure age overlying
the true “grauwacke”; and later, in 1839, following a
