One of the big debates among 19th century geologists revolved around the uniformity of the processes of nature. Those who believed that all the earth formations we see today are the results of slow, gradual forces of erosion and weathering were known as uniformitarians. Those who thought that there had been massive "earth changes" in the past, and usually subscribed to the idea that the Biblical Flood was a real historical event, were known as catastrophists. Darwin, Huxley, and other evolutionary scientists were inclined toward the uniformitarian theory, because it provided the massive time-scale needed for natural selection to operate to produce the diversity of life forms seen today. If there were vast, periodic extinctions, then natural selection would have to "start over" frequently and might not have made the "progress" to the higher life forms seen today. Most geologists and evolutionary biologists still lean toward the uniformitarian doctrine today, especially now that the role of continental drift in volcanism and other geological changes is understood.
This is largely also due to the fact that most modern
catastrophists often attach themselves to somewhat crankish or ridiculous
opinions. Many are outright "creation scientists" who feel Genesis offers
a literal description of the creation of the Earth. Others are followers
of
The two basic perspectives, of course, go back to the Greeks and undoubtedly much earlier. In the uniformitarian perspective, the Earth's features evolved through slow, continual processes, and the lifeforms we see today are the result of long, gradual, uninterrupted evolution. According to the 'new' catastrophists, the Earth has been impacted by various external forces, perhaps at regular intervals, causing rapid geological and other changes, and these have led to sudden extinctions and evolutionary discontinuities. Physical and biological evolution may have been, well, nonlinear. Old catastrophists tended to look for singular Biblical cataclysms like the Deluge as causes. The new catastrophists tend to suspect astronomical (meteors, comets, etc.) and climactic (i.e. Ice Ages, sudden warming) causes, which may be periodic in nature.
Yet within serious scientific circles some new attention is being payed to catastrophism. Because of Lovelock and Margulis' Gaia hypothesis, some scientists now feel that the ecology and geology of the planet may be more closely interrelated than was previously expected. Margulis feels that one of the greatest planetwide extinctions may have taken place upon the proliferation of the planet's first 'poison,' oxygen, which wiped out untold numbers of anaerobic bacteria. Evolutionists have begun to puzzle over incidences of 'punctuated equilibrium,' where evolutionary history often displays periods of rapid and explosive change. Some feel that vast changes may have taken place, such as Ice Ages, inundations of continental landmasses, or reversals of the planet's geomagnetic field, which provoked such periods of rapid extinction and genetic selection. Catastrophism may provide the answers for some perplexing evolutionary dead ends, which previously were merely Bible fodder for creationists.
Some of the renewed interest in catastrophism comes from a growing system approach. It is easy to be a uniformitarian if one posits an Earth floating isolated from cosmic influences, as a closed system subject only to its own internal laws. Yet one cannot deny the evidence - the sunspot cycle and solar upheavals are literally 'inscribed' in the rings of trees, showing that cosmic influences may cause geological, meterological, and geomagnetic changes which rewrite the tapestry of life. These 'interruptions' from outside in the narrative of life may be vitally necessary. Those who have studied disequilibrial (nonlinear) thermodynamics realize there is only one way to beat the entropy game: to have an open system that can 'borrow' order from some place else. If not for the random Brownian motion of water molecules, organic molecules might have had a tough time getting formed. Order can erupt spontaneously, but it requires chaos in order to do so! "One measures a circle, beginning anywhere..."
In puzzling over the riddle of the dinosaurs' demise, some scientists have even begun to wonder whether some cosmic phenomena may have altered life on Earth after all. The Nemesis hypothesis suggests that a 'dark planet' out in the Oort Cluster may periodically send forth a rain of comets into the solar system, at 65 million year intervals. Other researchers, based on crater and fossil evidence, feel it may have been a massive meteor impact that did in the dinosaurs. Some scientists feel that there may have been massive climactic changes in the past which resulted from a celestial body passing close to Earth and disturbing its orbit. One scientist has even advanced the hypothesis that most of the Earth's water has come from infinitesmally small 'minicomets' which pass rapidly through its orbit. Fred Hoyle has even suggested that life may have been 'seeded' on Earth by comets. The idea of life originating in Heaven still has a grip on the scientific mind, it seems.
Geologists have now found much evidence to indicate that land and sea have indeed changed places. We know many examples of volcanic landmasses emerging from the sea, only to blow to pieces or crash back down into the depths again. Where the Sahara Desert is now, there was apparently a very fertile, well-watered plain some 10,000 years ago. Apparently, following the end of the last Ice Age around that period, sea levels rose an incredible amount, and the Mediterranean basin was formed. There are many odd geological formations around the world - some were noted by Velikovsky in his Earth in Upheaval - which suggest some rapid, powerful force or impact, much like that seen in the wake of the Tunguska Incident of 1908, which flattened trees for miles. The Earth does appear on occasion to be have been the site of explosive change in its 4 1/2 billion year history - but scientists are still trying to puzzle out whether or not that may be the cause of periodic, regular extinctions.
But why all the enthusiasm with catastrophism? It may have to do with man's projected concern over the vast ways he is currently changing the planet - atmospheric change, desertification, pollution, extinction of "key" species, etc. Perhaps, in his zeal to discover whether such rapid ecological changes might cause his own rapid extinction, man has come to focus heavily on the possibility of such changes in the past and what effects they may have had on the planet's biota. Or maybe, just maybe, catastrophism is man's own way of warning himself, "Hey, slow down, before it's too late!" Maybe he wants to know if Gaia is ready to spit him out, the way it appears to have done to 99% of the animal species prior to him? It doesn't take a New Age conscience to wonder about that. A catastrophist framework makes any theory of Victorian progress tenuous, and leaves it in jeopardy. Not surprisingly, in our postmodern times, catastrophist theories of knowledge have also grown recently - such as Kuhn's paradigm model which suggests knowledge changes in sudden and discontinuous ways, rather than as a steady accumulation of increasing and reinforcing facts and figures.
The new awareness of previous extinctions in the geological record has led to a considerable concern about 'rogue meteors.' If our planet has suffered many mass extinctions in the past from meteor strikes, when might the next one be due? The problem is, there are so many meteoric objects in the "lethal" range (enough to generate explosions hundreds of times more powerful than H-bombs, possibly causing a deadly 'nuclear winter' of their own) which cross the Earth's orbit, and so few astronomers looking for them, that right now we have no idea. Even recently there have been quite a few close calls (in astronomical terms, of course.) Unfortunately, at the moment, we lack a means of rapid evacuation of the planet, but there are proposals for a space-based form of defense...
Forteans should be interested in the way in which many geological anomalies may fit within a catastrophist framework. Catastrophism also may help to explain some of the weird teleological and anomalous events in natural history, such as neoteny, where organisms regress to an infantile state in order to move forward evolutionarily. Mostly, catastrophism is an important part of the Fortean worldview. The doctrine of uniformitarianism was part and parcel of the deterministic Laplacean framework, which offered scientific prediction an air of omnipotence, and a reinforcement for the Victorian feeling of being at the pinnacle of 'progress,' at the apex of life on Earth. But in these days of mathematical "catastrophe theory," we know that normal systems can be subject to rapid fluctuations - including, one might point out, any multiple-body system such as our own solar system. (oh no... not Velikovsky again?) In a world where the impossible can and does happen, it is not surprising to find the processes of geological and biological change operating under forces that are not just slow, steady, continuous, linear, and constant, but... Fortean.
All sorts of Fortean terrain are opened up by viewing the Earth in a catastrophist framework. The riddle of artefacts encased deep within the crust of the planet, and the disappearance of advanced civilizations, can have a framework of explanation opened through catastrophism. There are many esoteric or mythic traditions which suggest that there may have been a companion to the Earth prior to the existing Moon, or that the planet's axis of declination may have been shifted, or that its direction and rate of rotation around the sun may have changed in the past. These cosmological phenomena might offer possible causes for previous Earth catastrophes, and are worthy of serious scientific explanation, not just crankish foaming at the mouth. Perhaps such cosmic catastrophes even rip frogs up into the sky, only to drop them down ages later... ?