Great Geologists | 63
Lapworth’s original hand drawn and coloured interpretation of the classic Dob’s Linn outcrop, key to his understanding of Paleozoic
stratigraphy and structure in the Southern Uplands. Image provided and used with the permission of the Lapworth Museum of
Geology.
Murchison and Cambrian by Sedgwick. Put simply, Murchison
wished to extend Silurian downwards to the base of all strata
containing fossil remains, and Sedgwick wished to extend
Cambrian upwards to the base of an unconformity seen in the
Welsh Borderlands (the base of Murchison’s Upper Silurian).
Rock units termed the Llandeilo and Caradoc series were
claimed by Murchison for the Silurian and by Sedgwick for the
Cambrian.
From his knowledge of fossil faunas, Lapworth took a
straightforward approach to resolving this problem. The Lower
Palaeozoic could simply be divided into three main epochs
—Cambrian and Silurian, with a new term, Ordovician, for
the strata lying between them. Each was readily definable in
terms of biostratigraphy. This approach was outlined in 1879
(after the deaths of both Sedgwick and Murchison). It found
favour with many academic geologists, but was resisted in
the Geological Survey, which was led by Murchison’s acolyte,
Geikie. After Geikie’s death in 1901, the Survey began to use
the term Ordovician officially, although it took until the meeting
of the International Geological Congress in Copenhagen in
1960 for it to be fully sanctioned by the international geological
community! Academic stratigraphic geology is not always
known for rapid decision making. Incidentally, the Global
Stratotype Section and Point (GSSP) for the base of the Silurian
system was placed within the Dob’s Linn section in 1985.
By 1881, Lapworth’s standing in the geological community
was such that he was appointed Professor of Geology and
Mineralogy at Mason’s College in Birmingham, the forerunner
to the University of Birmingham, which was founded in
1900. He served the university with great distinction until his
retirement in 1913, building a department that became one