Geology Reference
In-Depth Information
A problematic detail, however, muddied the waters—some fossils did not correspond to
any known living species. One of the most striking fossils common in the layered (sed-
imentary) rocks of England were ammonites, snail-like marine animals with spiral shells
characterized by distinctively crenulated partitions that created internal chambers. There
was a dizzying array of different species and types of fossil ammonites, ranging in size
from inches to several feet across. They were found throughout certain rock formations
across southern England and were literally falling out of the cliffs to litter beaches along the
English Channel. Yet nothing like them had ever been found alive anywhere in the world.
Their closest living relative seemed to be pearly nautilus, an exotic chambered shell with
simpler, noncrenulated partitions from the East Indies. Most natural philosophers shrugged
off this problem, confident that someday someone would dredge a living ammonite up from
the sea. They thought that only a flood of awesome power, the biblical flood, could have
entombed on land creatures thought to live in the very deepest part of the ocean.
The views of diluvialists—those who invoked Noah's Flood to explain what they found
in the rocks—dominated geological thinking until natural philosophers demonstrated that
fossils were extinct and that Earth had a much longer and more complicated history.
A leading voice of the diluvialists was Johann Scheuchzer, one of continental Europe's
great fossil enthusiasts. After completing a doctorate in medicine at Utrecht in 1694, he re-
turned home to Zurich, where he eventually became a professor of mathematics. Insatiably
curious about the natural world, Scheuchzer served as the secretary of a weekly club that
held lively discussions on controversial topics such as whether the devil could physically
seduce a woman and whether mountains were created along with the world or formed dur-
ing Noah's Flood.
Scheuchzer's passionate interest in Swiss natural history led to extensive walking tours
through the Alps. Accompanied by his students, he made geological observations and
was the first to measure—by carrying a barometer up a mountainside—how air pressure
changed with altitude. Fossils especially fascinated him. He had been taught they were
mineral oddities whose origin could be explained by physics and chemistry.
When Scheuchzer read Woodward's essay, he realized that fossils really were ancient
creatures. Right under his nose, entombed in his own rock collection, were the remains
of snails, seashells, fishes, and plants. This revelation prompted his own landmark work
