Geology Reference
In-Depth Information
concluded that each catastrophe recorded another transition in a long series of geological
eras. Ever since, these two views of geologic change—slow and steady versus catastroph-
ic—have framed competing theories for how the world is shaped.
The idea that a catastrophic biblical flood could have remodeled the European landscape
was vividly reinforced in 1818, when the Getroz glacier dammed the river Dranse in
Switzerland's Val de Bagnes. Advancing like the glacier that dammed the Tsangpo in Tibet,
the ice blocked the river and a lake holding eight hundred million cubic feet of water
formed above the frozen impoundment. When a tunnel was cut through it to draw down the
lake, the ice and debris dam failed, sending a wall of debris-charged water surging down
the valley at more than thirty feet a second. The flood swept away landmarks as sand and
mud filled the local church to the pulpit. Huge boulders lay strewn around the fresh depos-
its. As residents dug out from the mess, they discovered trees and houses swept away in
the torrent. The event impressed natural philosophers with how catastrophes could blanket
large areas under sediment. Here, perhaps, was an analog for the geological signature of
really big floods. The deposit left by this modern catastrophe looked a lot like the blanket
of sand, gravel, and mud that covered much of northern Europe.
Again, Cuvier led the way in elaborating the power and dynamism of geological pro-
cesses in his 1825
Discourse on the Revolutions of the Globe
. He made the case that dis-
tinctive animals lived during different epochs of earth history and described how abrupt
discontinuities between geological formations with different fossil assemblages testified to
periodic catastrophes having remodeled the world. In his view, the most recent catastrophe
was a sudden flood that separated the relatively short history of humanity from the depths
of geologic time. Cuvier's contention that one could not explain the geologic record solely
by means of existing causes—that the processes that shaped Earth's surface were different
in the past—became known as catastrophism, and stood in direct contrast to Hutton's artic-
ulation of how things happened gradually through many small changes, a view that became
known as uniformitarianism.
Cuvier's idea of periodic cataclysms seemed to address otherwise perplexing observa-
tions. His compelling evidence for the repeated destruction of former worlds inspired geo-
logically literate clergy to reinterpret Genesis. As early as 1816 the Stackhouse Bible cau-
tioned readers, “Moses records the history of the earth only in its present state… . There is
