Geoscience Reference
In-Depth Information
inDays, with the Cambrianwithin the first day and the Tertiary in the
sixth and final day. Even today, there are communities who still cling
to such beliefs.
From about the first decade of the eighteenth century, geologists
and gentlemen of science began to examine the sequences of rocks in
far greater detail than had their predecessors, and soon they realised
that the earlier classification was too simple, and that succession was
far more complex. Lithologically the rock types were quite varied, and
their origins could not be ascribed to earlier interpretations. Within
Europe a number of schemes that gave descriptive terms to various
distinctive portions of the geological succession were promoted, and
there was no clarity or accepted terminology. This meant in practice
that it was difficult for a French reader of a paper published in England
to appreciate fully which horizon was being written about, and to
correlate it with continental horizons with which he might have
been familiar.
In Britain the first descriptive table of strata was published as
early as 1719 by John Strachey, the mineral prospector and surveyor.
Strachey tabulated and named the succession in ascending order of
age: Mineral-bearing rocks below the Coal Measures, Coal Measures,
New Red Sandstone, Lias, Oolite, Chalk. He later expanded this work
and produced a pamphlet entitled Observations on the Different
Strata of Earths and Minerals, More Particularly of Such as are
Found in the Coal-mines of Great Britain. At many large geological
congresses held today a glossy card printed with the geological column
will be available; often the size of a credit card, it fits easily into a
wallet, and can be surreptitiously whipped out during a Friday night
table quiz down at the local pub, or equally easily by a forgetful
geologist fearful of being embarrassed in front of his or her peers. If
you compare Strachey's efforts with this geological column, immedi-
ately it will be clear that some terminology is common to both, and
that the arrangement of Strachey is somewhat familiar. In essence he
compiled an early version of the modern-day geological column.
Similar tabulations were erected by others, and terminology proliferated.
