Geology Reference
In-Depth Information
ing that it is so . . . The whys and wherefores cannot come with-
in the Province of a Mineral Surveyor.' Nevertheless, he certainly
had a feel for the immensity of time that was reflected in the
rock strata he surveyed, declaring: 'The time required for [each]
Perfection and Decay and subsequent formation into Strata . . .
would stagger the faith of many'.
Smith made the first geological map of the 'Strata of England
and Wales' which, had he been able to publish it immediately
upon completion, would have put him closer to the forefront of
geological fame. But he did not publish until 1815, and during
the time that elapsed between making it and publishing it he
discussed his ideas widely with his contemporaries such that
the information he possessed became di¬used throughout the
geological community by word of mouth, contributing signifi-
cantly to the progress of that science, but without its author
getting due recognition. So by the time Charles Lyell was a
geologist this crucial understanding that fossils allowed the
rocks to be ordered one above the other in a chronological
sequence had become an accepted meme.
During the course of his work Lyell examined the great vol-
cano of Etna on Sicily and studied the historical records of its
frequent eruptions. He noticed how each time it erupted a new
layer of lava would be added on top of the previous one, caus-
ing the mountain to grow at a measurable rate. So by knowing
the total height of the volcano, its approximate rate of growth
and the frequency of eruptions, Lyell realised that it should
be possible to estimate the age of the volcano. He did the cal-
culations and determined that it must be several hundred
thousand
years old. While this in itself was an astounding reve-
lation, the question remained, how much of geological time did
a hundred thousand years represent? Had the volcano been
growing ever since the world began, or was it a recent
phenomenon? At the edge of the volcano, underneath the first
lava flows, Lyell found fossil shells that were virtually identical
to the shells of molluscs swimming in the Mediterranean at that
