Mount St. Helens, 9:00 am, May 17, 1980.
Eruption column around 8:35 am on May 18, 1980.
Catastrophism was the theory that the Earth had largely been shaped by sudden, short-lived, violent events, possibly worldwide in scope. This was in contrast to uniformitarianism (sometimes described as gradualism), in which slow incremental changes, such as erosion, created all the Earth's geological features. Uniformitarianism held that the present was the key to the past, and that all geological processes (such as erosion)
throughout the past were like those that can be observed now. Since the
early disputes, a more inclusive and integrated view of geologic events
has developed, in which the scientific consensus
accepts that there were some catastrophic events in the geologic past,
but these were explicable as extreme examples of natural processes which
can occur.
Catastrophism held that geological epochs had ended with violent and sudden natural catastrophes such as great floods and the rapid formation of major mountain chains. Plants and animals living in the parts of the world where such events occurred were made extinct,
being replaced abruptly by the new forms whose fossils defined the
geological strata. Some catastrophists attempted to relate at least one
such change to the Biblical account of Noah's flood.
The concept was first popularised by the early 19th-century French scientist Georges Cuvier,
who proposed that new life forms had moved in from other areas after
local floods, and avoided religious or metaphysical speculation in his
scientific writings.
History
Geology and biblical beliefs
In the early development of geology, efforts were made in a predominantly Christian western society to reconcile biblical narratives of Creation and the universal flood
with new concepts about the processes which had formed the Earth. The
discovery of other ancient flood myths was taken as explaining why the
flood story was "stated in scientific methods with surprising frequency
among the Greeks", an example being Plutarch's account of the Ogygian flood.
Cuvier and the natural theologians
The leading scientific proponent of catastrophism in the early nineteenth century was the French anatomist and paleontologist Georges Cuvier. His motivation was to explain the patterns of extinction and faunal succession that he and others were observing in the fossil
record. While he did speculate that the catastrophe responsible for the
most recent extinctions in Eurasia might have been the result of the
inundation of low-lying areas by the sea, he did not make any reference
to Noah's flood.
Nor did he ever make any reference to divine creation as the mechanism
by which repopulation occurred following the extinction event. In fact
Cuvier, influenced by the ideas of the Enlightenment and the intellectual climate of the French revolution, avoided religious or metaphysical speculation in his scientific writings. Cuvier also believed that the stratigraphic
record indicated that there had been several of these revolutions,
which he viewed as recurring natural events, amid long intervals of
stability during the history of life on earth. This led him to believe
the Earth was several million years old.
By contrast in Britain, where natural theology was influential during the early nineteenth century, a group of geologists including William Buckland and Robert Jameson
interpreted Cuvier's work differently. Cuvier had written an
introduction to a collection of his papers on fossil quadrupeds,
discussing his ideas on catastrophic extinction. Jameson translated
Cuvier's introduction into English, publishing it under the title Theory of the Earth.
He added extensive editorial notes to the translation, explicitly
linking the latest of Cuvier's revolutions with the biblical flood. The
resulting essay was extremely influential in the English-speaking world.
Buckland spent much of his early career trying to demonstrate the
reality of the biblical flood using geological evidence. He frequently
cited Cuvier's work, even though Cuvier had proposed an inundation of
limited geographic extent and extended duration, whereas Buckland, to be
consistent with the biblical account, was advocating a universal flood
of short duration. Eventually, Buckland abandoned flood geology in favor of the glaciation theory advocated by Louis Agassiz,
following a visit to the Alps where Agassiz demonstrated the effects of
glaciation at first hand. As a result of the influence of Jameson,
Buckland, and other advocates of natural theology, the nineteenth
century debate over catastrophism took on much stronger religious
overtones in Britain than elsewhere in Europe.
The rise of uniformitarianism in geology
Uniformitarian explanations for the formation of sedimentary rock and an understanding of the immense stretch of geological time, or as the concept came to be known deep time, were found in the writing of James Hutton, sometimes known as the father of geology, in the late 18th century. The geologist Charles Lyell
built upon Hutton's ideas during the first half of 19th century and
amassed observations in support of the uniformitarian idea that the
Earth's features had been shaped by same geological processes that could
be observed in the present acting gradually over an immense period of
time. Lyell presented his ideas in the influential three volume work, Principles of Geology,
published in the 1830s, which challenged theories about geological
cataclysms proposed by proponents of catastrophism like Cuvier and
Buckland.
From around 1850 to 1980, most geologists endorsed uniformitarianism ("The present is the key to the past") and gradualism (geologic change occurs slowly over long periods of time) and rejected the idea that cataclysmic events such as earthquakes, volcanic eruptions,
or floods of vastly greater power than those observed at the present
time, played any significant role in the formation of the Earth's
surface. Instead they believed that the earth had been shaped by the
long term action of forces such as volcanism, earthquakes, erosion, and
sedimentation, that could still be observed in action today. In part,
the geologists' rejection was fostered by their impression that the
catastrophists of the early nineteenth century believed that God was
directly involved in determining the history of Earth. Some of the
theories about Catastrophism in the nineteenth and early twentieth
centuries were connected with religion and catastrophic origins were sometimes considered miraculous rather than natural events.
The rise in uniformitarianism made the introduction of a new catastrophe theory very difficult. In 1923 J Harlen Bretz published a paper on the channeled scablands formed by glacial Lake Missoula
in Washington State, USA. Bretz encountered resistance to his theories
from the geology establishment of the day, kicking off an acrimonious 40
year debate. Finally in 1979 Bretz received the Penrose Medal; the Geological Society of America's highest award.
Immanuel Velikovsky's views
In the 1950s, Immanuel Velikovsky propounded catastrophism in several popular books. He speculated that the planet Venus is a former "comet" which was ejected from Jupiter
and subsequently 3,500 years ago made two catastrophic close passes by
Earth, 52 years apart, and later interacted with Mars, which then had a
series of near collisions with Earth which ended in 687 BCE, before
settling into its current orbit. Velikovsky used this to explain the biblical plagues of Egypt,
the biblical reference to the "Sun standing still" for a day (Joshua
10:12 & 13, explained by changes in Earth's rotation), and the
sinking of Atlantis. Scientists vigorously rejected Velikovsky's conjectures.
Current application
Neocatastrophism
is the explanation of sudden extinctions in the palaeontological record
by high magnitude, low frequency events (such as asteroid impacts,
super-volcanic eruptions, supernova gamma ray bursts, etc.), as opposed
to the more prevalent geomorphological thought which emphasises low magnitude, high frequency events.
Luis Alvarez impact event hypothesis
Over the past 25 years, a scientifically based catastrophism has
gained wide acceptance with regard to certain events in the distant
past. One impetus for this change came from the publication of a
historic paper by Walter and Luis Alvarez in 1980. This paper suggested that a 10 kilometres (6.2 mi) asteroid struck Earth 66 million years ago at the end of the Cretaceous period. The impact wiped out about 70% of all species, including the dinosaurs, leaving behind the Cretaceous–Paleogene boundary (K–T boundary). In 1990, a 180 kilometres (110 mi) candidate crater marking the impact was identified at Chicxulub in the Yucatán Peninsula of Mexico.
Since then, the debate about the extinction of the dinosaurs and other mass extinction
events has centered on whether the extinction mechanism was the
asteroid impact, widespread volcanism (which occurred about the same
time), or some other mechanism or combination. Most of the mechanisms
suggested are catastrophic in nature.
The observation of the Shoemaker-Levy 9 cometary collision with Jupiter illustrated that catastrophic events occur as natural events.
Comparison with uniformitarianism
One
of the key differences between catastrophism and uniformitarianism is
that uniformitarianism requires the assumption of vast timelines,
whereas catastrophism does not. Today most geologists combine
catastrophist and uniformitarianist standpoints, taking the view that Earth's history is a slow, gradual story punctuated by occasional natural catastrophic events that have affected Earth and its inhabitants.
Moon-formation
Modern theories also suggest that Earth's anomalously large moon was formed catastrophically. In a paper published in Icarus in 1975, William K. Hartmann and Donald R. Davis proposed that a catastrophic near-miss by a large planetesimal early in Earth's formation approximately 4.5 billion years ago blew out rocky debris, remelted Earth and formed the Moon, thus explaining the Moon's lesser density and lack of an iron core.
The impact theory does have some faults; some computer simulations show
the formation of a ring or multiple moons post impact, and elements are
not quite the same between the earth and moon.
