Geology Reference
In-Depth Information
Fossils could be used to reliably assess the age of strata in southern Europe, something
that could not be determined from mineral composition alone. The fossils in the younger
rocks at the top of the regional geological pile were more like the modern fauna than were
the fossils in the older rocks deeper in the section. The comings and goings of species from
the fossil record could be used to track geologic time. Lyell was hooked. Here was the key
to the grandest puzzle. The fossils in different rock formations could be read to tell geolo-
gic time. If you knew the mix of fossils in a rock formation, you could confidently deduce
its age relative to other formations.
When Murchison returned to London in August, Lyell traveled on to Sicily, ending his
career as a barrister. He was now a geologist, by accident rather than design. More than
anything else his exploration of European geology convinced him of the enormous span
of geologic time and that a global flood was not responsible for shaping the modern land-
scape. Perhaps Hutton was right after all. Maybe slow, steady change was the pace at which
the world worked.
On his way back to England, in February 1829, Lyell stopped in Paris to compare the
fossils he had picked up with those in the collections of French geologists. The proportion
of still-living species increased farther to the south—and higher in the regional stack of
rocks. Older rocks, lower down in the regional pile, held more species not represented in
the modern fauna. This didn't square with the traditional biblically inspired view that, ex-
cept for the Flood, everything's been the same since the Creation.
The trip through France and Italy convinced Lyell to try to sway public opinion away
from the misconception that Genesis precluded the immensity of geologic time. It was
an ambitious goal. Geological findings that contradicted conventional biblical interpreta-
tions weren't common knowledge, and geological audiences favored Cuvier's grand cata-
strophes to explain the geologic record. Few favored Hutton's style of uniformitarian think-
ing in which everyday processes slowly shaped the world. Writing for two audiences, Lyell
tried to counter the dominance of catastrophist thinking among his colleagues without
shocking the general public accustomed to the idea that Noah's Flood resurfaced our six-
thousand-year-old planet. In 1830, he put his legal training to work in his
Principles of
Geology
, building up an argument and defense against the reactionary outcry sure to fol-
low.
