Perilous Planet Earth
Trevor Palmer
Text of a Talk Presented to the Society for Interdisciplinary Studies, Redhill, Surrey,
24 September 2004
Historical Perspective
Throughout the first half of the twentieth century, the gradualistic paradigm, championed in the previous century by Charles
Lyell and Charles Darwin, had seemed beyond challenge. As envisaged by Darwin, biological evolution proceeded in a slow
and stately fashion, through the mechanism of natural selection. As he himself put it, \u2018It may be said that natural selection is
daily and hourly scrutinising, throughout the world, every variation, even the slightest; rejecting that which is bad, preser ving
and adding up all that is good; silently and insensibly working, whenever and wherever op portunity offers, at the improvement
of each being in relation to its organic and inorganic conditions of life. We see nothing of these slow changes in progress, until
the hand of time has marked the long lapses of ages\u2026\u2019.
In Darwin\u2019s view, \u2018The extinction of species and of whole groups of species, which has played so conspicuous a part in the
history of the organic world, almost inevitably follows on the principle of natural selection; for old forms will be supplant ed by
new and improved forms\u2019.
In contrast to this notion of extinction through competition, as new, improved species gradually developed, nineteenth
century catastrophists such as Adam Sedgwick, William Buckland and William Whewell, saw the extinction of species as
evidence of episodic global convulsions. Their proposed mechanism, based on the ideas of the French geologist, L\u00e9once \u00c9lie
de Beaumont, was that the gradual cooling of the Earth from an incandescent beginning gave rise to a periodic wrinkling of th e
crust, producing new mountain ranges and causing volcanic activity, tidal waves and the extinction of species. However, as
evidence accumulated during the late nineteenth century, it became clear that there had been no world -wide episodes of
mountain-building, and no general link between mountain-building and the extinctions of species.
Thus, the cooling Earth model for global catastrophes was ruled out, and no plausible alternative could be found. Hence,
evolutionary gradualism dominated, in supreme fashion, for over half a cent ury. Similarly, for events in historical times, it was
widely believed that the rise and fall of civilisations depended solely on human activity and never on large-scale environmental
crises.
In the middle of the twentieth century, Immanuel Velikovsky challenged this prevailing gradualistic paradigm, his first book,
Worlds in Collision, appearing in 1950. Taking at face value the stories of celestial battles in ancient myths from around the
world, Velikovsky suggested that, on several occasions in historical times, other planets of the Solar System had wandered into
the vicinity of the Earth, giving rise to global catastrophes. In particular, Venus, then possessing a comet-like tail, had made a
close passage around 1450 BC, causing great problems for humankind, including the plagues of Egypt mentioned in Exodus
(which allowed him to date the event, on the basis of Jewish tradition). In attempting to reconcile Egyptian accounts with th ose
of the Old Testament, Velikovsky concluded that the \u2018Venus event\u2019 had occurred in the period leading up to the conquest of
Egypt by the Hyksos, conventionally dated at around 1650 BC. Hence, since this date differed by two centuries from the one
he accepted for the Exodus event, Velikovsky deduced that the conventional chronology must be incorrect, and he proposed a
revised one.
Velikovsky was not the first to challenge the gradualistic paradigm in the twentieth century, but previous attempts had made
little impact. In contrast, the powerful new synthesis proposed by Ve likovsky, linking together mythology, astronomy, ancient
history and chronology, caught the imagination of many. Nevertheless, it was highly controversial, and dismissed out of hand
by most orthodox academics, who deemed it unworthy of serious consideration. As a consequence, the Society of
Interdisciplinary Studies (SIS) was formed in 1974, to provide a forum for the open -minded discussion of Velikovsky\u2019s ideas,
together with other aspects of catastrophism and chronology.
Catastrophism today
Thirty years on, Velikovsky\u2019s theories remain as controversial as ever. Leaving aside awkward questions such as how a
planet could possess a comet-like tail, a particular problem is how a wandering Venus could have moved into its present orbit,
which is almost circular. Although, as pointed out by Laurence Dixon in 2002, a solution is possible which is consistent with
the principles of conservation of energy and angular momentum, this would require the Earth to have had its first contact wit h
Venus in a position almost halfway to the Sun from where it is now. That would have put it well beyond the \u2018habitable zone\u2019,
where water can exist in liquid form at the surface of a planet. Regardless of that, the proposed timescale presents another
major difficulty. Even Velikovskian sympathisers such as Wal Thornhill have acknowledged that, if Venus had passed close to
Earth in 1450 BC, Newtonian mechanics would require its present orbit to be far more elliptical than is the case. Eric Crew,
writing in 1997, concluded that not even the introduction of hypothetical electrostatic interactions, in line with Velikovsky\u2019s
suggestion on the penultimate page of Worlds in Collision, could reconcile the current orbit of Venus with the Velikovskian
scenario
According to Thornhill, writing in 1998, the only way out was to argue that our present understanding of the nature of
gravity must be wrong. He continued, \u2018It is time to re-examine those \u201claws\u201d or long-held beliefs that have diverted scientific
curiosity away from uncomfortable questions about the safety of our spaceship Earth. We can no longer afford to deny the
possibility that global myths and images of the planetary gods may refer to a frighteningly close -up view of the planets within
the memory of the human race.\u2019
However, most scientists, when presented with a situation where either Velikovsky had drawn incorrect conclusions from
ancient myths or else there was something fundamentally wrong with the laws of physics as we know them, unsurprisingly
supposed the former to be the case. Moreover, at least partially because of the renewed interest in catastrophism resulting from
Velikovsky\u2019s writings, they could now do so in full knowledge of several alternative threats to life on Earth, all of which were
consistent with observational evidence and the laws of physics. Velikovsky\u2019s scenario was no longer the only catastrophist
show in town. Some of the mechanisms involved in the new proposals, linking bright lights and loud noises in the sky with
catastrophes on Earth, could also have given rise to ancient myths.
One such example is a major volcanic eruption. The existence of volcanic eruptions has, of course, long been known, but
only recently has the possible scale of devastation become fully apparent.
Perhaps the best-known volcano is Vesuvius, whose explosive eruption in 79 AD destroyed the Roman cities of Pompeii and
Herculaneum. Another well-known explosive eruption was that of Mount St Helens in Washington State, USA, in 1980,
producing a crater 3.2 km in diameter and a pyroclastic flow which killed 62 people. The death count was low because very
few people lived in the region, but the blast created a wasteland with an area greater than 500 square kilometers within a fe w
minutes.
Yet the Mount St Helens eruption only had a Volcanic Explosivity Index (VEI) of 5 out of a possible 8. Moving up the scale,
the Bronze Age eruption of Thera in the Eastern Mediterranean, which seems to have destabilised the Minoan Civilisation
without bringing it to an immediate end, was a VEI 6 event. When the explosion was over, the centre of the volcano collapsed
into the empty magma chamber, leaving the outermost parts (the present -day islands of Santorini) as a circular caldera over 10
km in diameter. The eruption of Krakatoa in the East Indies in 1883 was slightly smaller, producing a caldera about half the
area of that of Thera. Nevertheless, it has been estimated that it released energy equivalent to 50 -100 megatons of TNT, at least
2,500 times that of the Hiroshima bomb, and tidal waves produced by the blast killed almost 40,000 people.
The eruption of nearby Tambora in 1815 had been even more powerful, with a VEI of 7. After the explosion, a dust cloud
blocked out the Sun\u2019s light for 2 days up to a distance of 600 km from the volcano. The following year, 1816, was remembered
as the \u201cyear without a summer\u201d in the northern hemisphere, abnormally low average temperatures being recorded in both
Europe and North America, because of volcanic dust in the upper atmosphere. Eruptions on this scale can be expected
somewhere on Earth at intervals of between a few hundred to a few thousand years. Even more powerful super -eruptions, with
a VEI of 8, occur every 100,000 years or so, on average, in the generally-accepted geological timescale.
The most recent VEI 8 super-eruption was Toba in the East Indies 75,000 years ago. This was perhaps 100 times more
energetic than the Krakatoa blast, producing a caldera over 50 km in diameter. The explosion heralded the onset of the W\u00fcrm
glaciation when, as inferred from the evidence of our low genetic diversity, the entire human population of the world dropped
to less than 10,000. There have been four explosions of similar magnitude in and around the Yellowstone Park area of North
America during the past 2 million years (Myr), and there are indications that another could be on the way.
During the past 400 Myr, there have been several episodes of massive vulcanism over extensive geographical regions. For
example, there were huge outpourings of lava in Eastern Europe around 365 Myr ago; in Siberia around 250 Myr ago; in the
Central Atlantic region around 210 Myr ago; in the Pacific and Indian Oceans around 100 Myr ago; in India around 65 Myr
ago; and in Ethiopia around 30 Myr ago. Such vulcanism, even if o f a non-explosive nature, must have caused considerable
destruction of living organisms. The contamination of the atmosphere with volcanic dust and gas would have blocked out
sunlight and reduced average temperatures for a considerable period of time. It would also have limited photosynthesis,
disrupting food chains on land and in the oceans.
The battles in Greek mythology between the Olympian gods and the Titans and Giants, when huge rocks and fire -brands
were hurled around as weapons, suggest a volcanic scenario, as does the fact that Zeus clashed with the monstrous Typhon
(also known as Typhoeus) near Mount Vesuvius and finally trapped him under Mount Etna. However, the Roman author, Pliny
the Elder, wrote that Typhon was the name given to a terrifyi ng comet, which was of \u201cfiery appearance\u201d and \u201ctwisted like a
coil\u201d. As we now know, comets and asteroids are other potential causes of global catastrophes.
The situation had seemed very different in 1950, when Velikovsky\u2019s Worlds in Collision first appeared. Comets had been
feared in ancient times, but, more recently, several centuries of scientific observation had revealed nothing to suggest they
offered a serious threat to the Earth. Similarly, no asteroid was found to be in an Earth-crossing orbit until 1952. Today, it is
known that there are a large number of asteroids in orbits which threaten the Earth, of which around a thousand have a
diameter greater than 1 km and a few greater than 10 km. Estimates suggest that several 1 km asteroids will strik e the Earth
every million years, and several 10 km asteroids will impact in a 500 Myr period. It has become clear that a 1 km asteroid wi ll
have an impact energy in excess of a million megatons of TNT, i.e. at least 50 million times more powerful than the Hiroshima
bomb, whereas a 10 km asteroid will have an impact energy of more than 100 million megatons. Velikovsky, in common with
his more orthodox contemporaries, could never have envisaged an asteroid causing an explosion on anything like this scale.
Cometary nuclei may be lighter than asteroids of similar size, but they are likely to be travelling faster relative to the Earth,
so could be just as devastating on impact. The collision of Comet Shoemaker -Levy 9 with Jupiter in 1992 demonstrated that
comets can, and do, strike planets. The nuclei of comets are typically in the range 1 -10 km, but some can be much larger. In
1997, Comet Hale-Bopp, with a nucleus whose diameter was at least 10 km and possibly more than 50 km, passed the Earth at
a comfortable distance. However, for all we knew at the time of its first appearance in 1995, it could have been heading
straight for us.
In the first half of the twentieth century, no large craters on the surface of the Earth were recognised as being of impact
origin. The problem was that they were circular rather than oval, the shape it was assumed would be punched out by an
extraterrestrial object arriving at a \u2018typical\u2019 angle. Also, no large meteorites could be found buried within them. Those craters
observed to be oval and containing meteorites were all small, no more than around 20 metres in length, which hardly suggested
much of a threat to Earth. However, during the 1960s, studies showed that a large projectile would maintain a faster speed
through the atmosphere than a small one and would explode on impact, destroying itself and producing a large, circular crater.
So, should a 10 km extraterrestrial object, be it an asteroid or a comet, strike in the Luton\/Bedford area, the crater formed
would be around 180 km in diameter, stretching from London to Nottingham. An intense fireball would rise from the impact
site, causing conflagrations and producing gases which would later fall as acid rain. Whilst molten rock and ash would fall
back to Earth, a large amount of dust would spread through the upper atmosphere, obscuring the light of the Sun for several
months. As in the case of extensive vulcanism, this would cause global cooling and disrupt food chains.
Three terrestrial impact craters of around 100 km diameter have been recognised for some time, each of which must have
been caused by the impact of a projectile of around 5 km in diameter. These are the structures at Puchezh -Katunki, Siberia, and
Manicouagan, Canada, both formed around 200 Myr ago, and another Siberian crater, the 35 Myr old Popigai structure. Now,
several even larger craters are known from the far -distant Precambrian period, as well as two others from more recent times: a
180 km diameter crater at Chicxulub, Mexico, the product of a 10 km projectile, and a 120 km diameter crater near Woodleigh,
Western Australia. Both of these escaped detection for many years because they are now covered with sedimentary rock to a
depth of hundreds of metres. Large projectiles may also have landed in the oceans, which cover 80% of the Earth\u2019s surface,
and where craters would be difficult to detect, or struck areas of great tectonic activity, where craters would be destroyed
relatively quickly. From astronomical data, it is thought that at least a third of la rge terrestrial impact craters will be products of
comets rather than asteroids.
As well as being responsible for individual large impacts, comets could also be a central feature of another catastrophist
scenario. According to British astronomers, Victor Clube and Bill Napier, supported by others such as Mark Bailey and David
Asher, giant comets with nuclei as large as 200 km in diameter are likely to enter the inner Solar System from time to time and
break up because of the gravitational effects of the Sun. This could result in the contamination of the Earth\u2019s atmosphere with
cometary dust, and a sustained bombardment by cometary fragments, which would be just as devastating as a single impact by
a larger projectile.
Yet another possible cause of catastrophe is the release of streams of lethal gamma-radiation close to the Earth, from a
supernova explosion or other cause. Four supernovae explosions, involving distant stars in our Galaxy, have been observed in
the past millennium. Had such an explosion occurred within 100 light years of the Earth, it would have caused severe damage
to animal and plant life, and calculations have indicated that several such events are likely to have occurred since life fir st
appeared on our planet.
Non-catastrophist mechanisms, particularly ones involving continental drift, could also be responsible for the mass
extinctions of species. Velikovsky was sceptical about the existence of continental drift, as was the scientific establishmen t
until the 1960s, but measurements have now shown that the continents are indeed moving relative to each other at about the
same rate that fingernails grow. Changes in the configuration of the continents over millions of years are likely to result i n
changes in patterns of ocean currents, changes in sea-level, changes in habitats and changes in climates, leading to the
disappearance of groups of living organisms.
Whatever the cause or causes of mass extinctions of species on particular occasions, it can now be seen that they played a
significant role in determining the overall trends of evolution. Extinctions at these times were not the result of competitio n with
new, improved species under stable environmental conditions, but a consequence of dramatic changes to the environment,
whether over a short or a long timescale. After the extinctions, it could take millions of years for nature to recover and restore
something approaching the previous diversity of living organisms but, even then, things could never be the same. Many
species, and their genes, had disappeared forever, and all subsequent evolution had to derive from the genes of the lucky
survivors, often doing so in surprising ways. As Simon Lamb and David Sington wrote in 1998, \u2018Each mass extinction has
proved to be a turning point in the development of life as the extinct species are replaced by an even greater variety of new
creatures, often characterised by the sudden appearance of novel features. Thus the slow and stately progress of evolution,
envisaged by Darwin, seems to have been interrupted by a number of abrupt events that have had a decisive impact on the
direction life has taken\u2019.
The \u2018big five\u2019 mass extinction events
Detailed studies of the fossil record have shown that mass extinction episodes occurred, on average, at intervals of around 30
Myr. None of these episodes were instantaneous. All seem to have involved the interplay of several factors, over a timescale of
perhaps several million years. Nevertheless, within some of the episodes, there was a particularly intense period of extinctions,
possibly indicating an additional jolt to a system already in crisis. During five of the episodes, well over half of all exis ting
species became extinct. These are known as the \u2018big five\u2019 extinctions.
Life had proliferated in the oceans during the Cambrian and Ordovician periods. Then, at the end of the Ordovician, about
440 Myr ago, came the first of the big five extinctions, when around 80% of all species died out. As Richard Foley, a
palaeontologist at the Natural History Museum in London, wrote in 1997, \u2018The end of the Ordovician was a punctuation mark
in the history of life, providing a natural end to the first great phase of diversification and reorganisation of marine life . Those
animals and plants that survived went on to make the modern world; had the list of survivors been one jot different, then so
would the world today\u2019.
At that time, Africa, then part of the southern supercontinent of Gondwana, drifted over the South Pole, providing a platform
for the establishment and expansion of a great ice-sheet, and the transmission of cold temperatures around the world. Sea levels fell, because of water trapped as ice, exposing organic matter to oxidation by the atmosphere. This led to an increase in
atmospheric carbon dioxide and a reduction in free oxygen. Then, as configurations changed, temperatures increased and the
ice melted, sea-levels rose rapidly and the oceans became anoxic, i.e. starved of oxygen. Anoxic oceans, resembling huge,
stagnant ponds, are typically produced when sea-levels rise following a previous fall. Whether this is the sole explanation for
the Ordovician extinctions is uncertain. However, as with several lesser extinction episodes, no convincing evidence of
extensive vulcanism or a major extraterrestrial impact at this time has yet come to light. Possibly a gamma -ray burst might
have been involved, but that is largely speculation.
When conditions eventually eased, fish proliferated in the seas for the first time, and amphibians began to colonise the land.
The next of the big five extinctions occurred in the Late Devonian period around 365 Myr ago, with the loss of about 60% of
existing species. Again, the extinctions are associated with a period of global cooling, this time linked to the passag e of South
America over the South Pole. As before, sea-levels fluctuated and the oceans became anoxic. However, on this occasion, there
is also clear evidence of additional factors. At around the time of the extinctions, extensive vulcanism took place on t he East
European platform and there was a cluster of extraterrestrial impacts, including the ones which produced the 120 km diameter
crater at Woodleigh, Western Australia, and 55 km craters at Charlevoix, Quebec, and Siljan, Sweden. There are also
indications of a large crater from this period in the Alamo region of Nevada, but this cannot be investigated properly because it
is located on military land, including the much-discussed Area 51, which features strongly in UFO legends.
Life eventually blossomed again, on land as well as in the sea. The proto-mammals (therapsids) eventually became the
dominant land animal. Then came the greatest mass extinction of all, at the end of the Permian period about 250 Myr ago,
when around 90% of species became extinct. The trilobites, which had been around for over 300 Myr since the Early Cambrian
period, were amongst the victims. The Late Permian extinctions occurred at a unique time in the Earth\u2019s history when all the
land-masses drifted together to form a single supercontinent, Pangaea. This would have greatly reduced the habitat area
available to creatures which lived in shallow coastal waters. It would also have brought previously isolated groups of land
animals into contact with each other, and introduced more continental-type climates, i.e. greater contrasts between summer and
winter. Furthermore, the southern tip of Pangaea was initially over the South Pole, but then the supercontinent drifted
northwards, eventually causing the ice to melt at one extremity and fresh glaciations to form at the other. Sea -levels fluctuated
and the oceans once again became anoxic. To add to the hardships for living organisms, extensive vulcanism occurred at this
time, with the laying down of the flood basalts of the Siberian platfor m, apparently as a consequence of the collision between
the Siberian and European plates, the final act in the creation of Pangaea. On top of all that, it is even possible there was a
major extraterrestrial impact at the end of the Permian period. Evidence for one has been claimed, for example, in the form of
fullerenes containing helium and argon with isotope ratios suggesting an extraterrestrial origin. A possible impact site is t he
200 km diameter Bedout structure, which lies under sediment off the coast of northwestern Australia.
Yet, somehow, life survived the transition from the Permian to the Triassic period. From the evidence of the fossil record, it
seems that only a very limited number of species were around during the first few million years o f the Triassic, but then there
was a sudden proliferation of life. On land, the proto-mammals, who had been badly hit during the Late Permian extinctions,
eventually staged a recovery, but they had to compete for supremacy with a new group of animals, the rhynchosaurs. The
proto-dinosaurs (thecodonts) also emerged at this time, but showed no obvious signs of being likely challengers for domination
of the land.
Then came the fourth of the big five extinctions, at the end of the Triassic period 210 Myr ago, when, at a relatively early
stage of the process, the rhynchosaurs died out completely and the proto -mammals disappeared from many parts of the world.
Once again, there may have been a fluctuation in sea-level and an anoxic period, but the details are less clear than on the three
previous occasions. More certainly, basalts in eastern North America, Brazil, Europe and West Africa, together constituting t he
Central Atlantic Magmatic Province (CAMP), were laid down around the this time, during a period of massive volcanic
activity that heralded the break-up of Pangaea and the opening of the Central Atlantic Ocean. There were also extraterrestrial
impacts during the Late Triassic, including a cluster which produced a line of craters from the 100 km diameter s tructure at
Manicouagan, Canada, through France to the Ukraine. These seem to have come too early to be associated with the extinctions
at the end of the period, although they must have contributed to the deterioration of the environment.
With the rhynchosaurs and proto-mammals wholly or partially removed from the scene during the Triassic-Jurassic
transition, the proto-dinosaurs were able to expand their territory without much opposition during the Early Jurassic, before
giving way to the dinosaurs themselves. The dinosaurs then dominated the land for around 150 Myr, throughout the rest of the
Jurassic and the whole of the Cretaceous period. Then came the last, and best-known, of the big five extinction events, 65 Myr
ago, when 70% of existing species disappeared, including all the dinosaurs. In the oceans, the great sea -reptiles became extinct,
as did the ammonites, whilst the flying reptiles disappeared from the skies.
Sea-levels fell consistently over the latter part of the Cretaceous period, drai ning the shallow seas which had covered much
of the continents, thereby changing habitats and climates. Average temperatures also fell consistently throughout the last fe w
million years of the Cretaceous. However, that was not the whole story. The finding in 1980, by Luis and Walter Alvarez of
the University of California, Berkeley, that the Cretaceous -Tertiary boundary throughout the world was marked by high
iridium levels, was important because this was the first serious indication that mass extinctions c ould have a catastrophist
explanation. Since iridium is normally only found in significant amounts in extraterrestrial materials or in the Earth\u2019s core , the
only possible explanations were widespread vulcanism or an extraterrestrial impact. In fact, both are now known to have
occurred at the end of the Cretaceous period. A million cubic kilometers of lava were released to form the Deccan traps of
India, and a 10 km projectile from space produced a 180 km diameter crater at Chicxulub, in the Yucat\u00e1n region o f Mexico.
Several other impacts had occurred in the last 10 Myr of the Cretaceous period, including the one that gave rise to the 65 km
diameter crater at Kara, in the Russian Arctic, and these might have contributed to the environmental deterioration whic h
undoubtedly occurred.
Whatever the precise details, the events of the Late Cretaceous had major implications for the future of life on Earth. As the
Cambridge University palaeontologist, David Norman, wrote in 1994, \u2018From an evolutionary point of view, any survivors of
the Cretaceous extinctions were handed a wonderful opportunity to evolve into the ecological niches that had been vacated by
the dinosaurs. The story of the Early Tertiary is just that \u2013 a time of rapid evolution and adjustment among the various
surviving groups\u2019.
However, there was nothing inevitable about the outcome of the process. The mammals, having lived in the shadow of the
dinosaurs for 150 Myr, took a long time to become established as the dominant group of land animals. Of the 15 known
families of mammals in the Late Cretaceous period, 10 survived into the Palaeocene, the first epoch of the Tertiary period,
probably because they were smaller and more capable of surviving extremes of temperature than the dinosaurs. However, t he
number of mammalian families did not exceed 70 until after the start of the Eocene epoch, ten million years later. During the
Eocene, the number rose to over 200 but then dropped back to less than 150 during another extinction episode towards the end
of the epoch, before rising further. The earliest mammals were all tiny shrew -like creatures and, although a few moderately
large ones appeared during the Palaeocene, it was not until the Oligocene epoch, after the Eocene had come and gone, that the
diversity of large mammals started to become comparable with that of the dinosaurs of the Cretaceous period.
Catastrophes in historical times
The emergence of humans from amongst the mammals was far from straightforward, being complicated by environmental
fluctuations, particularly during the Ice Ages of the Pleistocene epoch, which began around 2 Myr ago. As we have seen, our
species might have disappeared completely after the Toba super-eruption 75,000 years ago, and that was not the last of the
environmental crises. Temperatures continued to fluctuate, the coldest period of all, the \u2018glacial maximum\u2019, occurring between
around 25,000 and 19,000 years ago. A period of significant warming began about 14,000 years ago, but then temperatures
dropped sharply again around 13,000 years ago at the start of the Younger Dryas, the final stage of the Pleistocene.
Towards the end of the Younger Dryas came the great terminal thaw of the Pleistocene, leading to the start of the temperate
Holocene epoch around 11,000 years ago. Extinctions of animal species had occurred throughout the Pleistocene, but were
particularly marked near to or at its conclusion, when temperatures rose higher than they had been for the previous 100,000
years. Taken as a whole, the Late Pleistocene extinctions were on a much smaller scale than those of the big five, but large
land animals were profoundly affected. In North America, 33 genera (three quarters of the total, including all the mammoths,
mastodons, horses, tapirs and camels) disappeared between 12,000 and 10,000 years ago, whilst in South America over the
same period, 46 genera of large land animals became extinct. The extinctions in the Old World were more modest, but several
species of large animals disappeared completely from Africa at the end of the Pleistocene, and the mammoth, woolly
rhinoceros and giant deer became extinct in Europe at this time. The record in Asia is not documented so well as elsewhere
but, as is well-known, the mammoths of the Siberian steppe-tundra were amongst the victims of the Pleistocene-Holocene
transition. There has been much argument about whether these various extinctions of megafauna were caused by hunting
and\/or the transmission of diseases by humans (who began to colonise the Americas at this time), or by climate change, but it
is likely that several factors were involved.
There have also been many arguments about the cause of this climate change at the end of the Pleistocene epoch, proposed
mechanisms involving astronomical cycles, atmospheric concentrations of dust or greenhouse gases, deep-water flux in the
oceans and extraterrestrial impacts. Again, it seems that a combination of factors may have been involved. According to Clube
and Napier, the harsh conditions over the latter part of the Pleistocene Ice Age could be linked to the arrival in the Inner Solar
System of a giant comet, proto-Encke. This caused a dusting of the Earth\u2019s atmosphere, which later cleared, facilitating the
Pleistocene-Holocene transition. Others have suggested that an extraterrestrial impact at the end of the Pleistocene might have
changed the tilt of the Earth, and hence climates, although no clear evidence of an impact event at this time has yet been fo und.
Han Kloosterman has drawn attention to a charcoal band in Late Pleistocene rocks throughout Europe and North America,
marking the start of the Younger Dryas, which could possibly indicate a wide-scale conflagration linked to an impact. Also, it
was once thought that the Australasian tektite field had been laid down at the time of the Pleistocene-Holocene transition, but it
has now been shown that the impact which produced these tektites occurred much earlier in the Pleistocene.
Regardless of cause, the Pleistocene-Holocene climate change had profound effects, the melting of the ice leading to a rise in
sea-level of over 100 metres. For many years, it was generally assumed that this had been a gradual, even -paced process.
However, it now seems that it took place in rapid, although episodic, fashion. On the evidence of oxygen-isotope ratios in
Greenland ice cores, it seems that average temperatures rose by almost 10?C in a short period of time, probably less than a
decade, around 11,000 years ago. Low-lying regions throughout the world were flooded as sea-levels rose. Sometime there was
a long delay between cause and effect, perhaps increasing the catastrophic nature of the latter, when natural barriers held b ack
the rising waters in some regions for a time and then suddenly collapsed. For example, according to evidence as sembled by
geologists William Ryan and Walter Pitman, the Black Sea was initially sealed off from the Mediterranean by a natural dam in
the Bosporus region which burst around 7,600 years ago, expanding the area covered by the Black Sea by over 150,000 squa re
kilometres within a period of a year or so.
In the new environment of the Holocene, humans quickly became established as the dominant land animal and began to
develop civilisations, although, once again, this process was disrupted by environmental perturbations. Needless to say, an
environmental crisis far less severe than ones which caused mass extinctions of species, could be capable of destroying an
emerging civilisation.
Fledgling civilisations all around the Middle East were disrupted at the end of the Early Bronze Age, about 2300 BC in the
conventional chronology. This was first pointed out by the French archaeologist, Claude Schaeffer, and reinforced by Moe
Mandelkehr in a series of papers in the SIS Review. The Old Kingdom of Egypt, t he main period of pyramid construction,
came to a chaotic end, and the Akkadian empire in Mesopotamia encountered severe problems after its advance under Sargon
the Great. Investigations at Tell Leilan in northern Syria by the Yale archaeologist, Harvey We iss, showed that the climate in
this region suddenly became arid at this time. Weiss attributed this change in climate to a volcanic eruption, whereas one of his
collaborators, Marie-Agn\u00e8s Courty, of the French Centre for Scientific Research, subsequently thought that an extraterrestrial
impact was a more likely explanation. Courty presented her arguments at the Second SIS Cambridge Conference in 1997,
when Benny Peiser of Liverpool John Moores University and Mike Baillie of Queen\u2019s University, Belfast, also presented
evidence for cometary catastrophes of a wide-scale nature at the end of the Early Bronze Age.
At the Cambridge conference, and again in his 1999 book, Exodus to Arthur, Baillie pointed out that tree-rings in Irish oaks
demonstrated an environmental downturn which peaked in 2345 BC, shortly before the first major eruption of the Iceland
volcano, Hekla, in historical times. Baillie attributed both this eruption and the environmental downturn to an extraterrestr ial
bombardment, during one of the several encounters between the Earth and the disintegrating remains of comet proto -Encke
which, according to Clube and Napier, had occurred during the past 10,000 years. Amongst the products of this disintegration
were the present-day comet Encke, the beta-Taurid meteoroid stream and the Apollo asteroids, Oljato and Jason. Mandelkehr
subsequently expressed his support for this theory.
The next wide-scale disturbance occurred at the end of the Late Bronze Age shortly after 1200 BC when, according to
conventional history, the Mycenaean civilisation of Greece and the Hittite empire of Anatolia came to an end, whilst the new
Kingdom of Egypt slipped into disorder following the reign of Ramesses III. There is evidence that these events took place
against a back-drop of earthquakes and climate change. According to Baillie, Irish oak chronologies showed an environmental
downturn which peaked in 1159 BC, around the time of the second major eruption of Hekla in Iceland. Greenland ice -cores
showed an acidity peak, usually an indication of a large volcanic eruption, at or near to 1120 BC. Again, Baillie thought that
the Clube-Napier scenario provided the most likely explanation.
What about Velikovsky\u2019s proposed Venus catastrophe of 1450 BC, around the time the Middle Bronze Age came to an end?
Velikovsky undoubtedly deserved credit for alerting the world to the flaws in the prevailing gradualistic paradigm, and he
produced a catastrophist scenario which seized the imagination, particularly given the lack of plau sible alternatives known at
the time. However, were the historical details of his model consistent with the geological and archaeological evidence which
subsequently came to light? The answer has to be in the negative.
Although Velikovsky had acknowledged that there had been several global catastrophes before his proposed 1450 BC event,
producing impressive evidence of such occurrences, he nevertheless went on to suggest that large -scale catastrophic
extinctions of the Ice Age megafauna had occurred at the time of the Venus encounter, much later than generally supposed. In
apparent support of this notion, radiocarbon dating studies have now shown that mammoths were living on an island off the
northeastern coast of Siberia until around 2000 BC. However, rather than being of general significance, it seems that this was
the last refuge of the mammoths. These same radiocarbon dating studies, as well as others, have indicated that mammoths had
disappeared completely from the Siberian mainland by about 10,000 years ago, and similar results were obtained in Europe
and North America. Hence, geologists have found no evidence of a catastrophic mass extinction episode around 1450 BC.
Moreover, studies on Irish oaks revealed no indication of an environmental crisis at any time between 1628 and 1159 BC,
and that finding was generally consistent with other tree-ring evidence. Again, Greenland ice-cores showed no acidity peak
between about 1645 and 1390 BC. In Exodus to Arthur, Baillie suggested that the Thera eruption and the Exodus, both features
of Velikovsky\u2019s 1450 BC scenario, had actually occurred during a period of cometary bombardment around 1628 BC. In the
orthodox chronology, that would place the Exodus just before the conquest of Egypt by the Hyksos, as Veli kovsky had
suggested. In the revised chronology, on the other hand, both of those events occurred two centuries closer to our own time.
However, doubts have been expressed in some quarters about radiocarbon, tree-ring and ice-core dating procedures, so the
possibility cannot be excluded that incorrect dates have been obtained from such evidence by geologists and environmental
scientists.
Again, archaeologists could have been in error in failing to find evidence of widespread catastrophic destruction of
civilisations at or around the end of the Middle Bronze Age, conventionally dated to between 1500 and 1550 BC. However, the
implications of their reports, and those of studies of ancient sources, are clear: events which Velikovsky had grouped togeth er
as features of the 1450 BC \u2018Venus catastrophe\u2019 had occurred at significantly different times, some being more appropriately
associated with the end of the Early Bronze Age. At the First SIS Cambridge Conference in 1993, Bob Porter outlined the
archaeological evidence which showed far fewer indications of a global catastrophe at the end of the Middle Bronze Age than
at the end of the Early Bronze Age, and he concluded, \u2018Velikovsky\u2019s theory of massive planetary disruption in the Bronze Age
appears unnecessary, aside from its impracticality. \u2019 Different people may have different views about that. Since certainty is a
characteristic of religion rather than science, we cannot exclude the possibility that orthodox physicists, geologists,
environmental scientists and archaeologists have, independently, come to erroneous conclusions about events in the fifteenth
century BC, but where is the hard evidence to suggest that they have? Without question, those Velikovskians who wish to
uphold all the specific details of Worlds in Collision, Earth in Upheaval and Ages in Chaos, still have a great deal of work to
do if they are to persuade sceptics (including ones with no great love of orthodoxy) to pay serious attention to the notion t hat a
close approach of Venus caused global catastrophes on Earth around 1450 BC.
Finally, let us look at a time of crisis in the Early Medieval period. In the middle of the sixth century AD, the Byzantine
historian, Procopius, wrote of terrible conditions in parts of northern Europe, particularl y the west of Britain, and a similar
picture was presented in some of the Arthurian romances. In China at around the same time there were great falls of yellow
dust and an environmental downturn, which triggered a civil war. Central America suffered a drought which caused a wellestablished \u2018hiatus\u2019 in the Classic Mayan civilisation, whilst cultures along the Pacific coast of South America were also
disrupted by a prolonged lack of rainfall. Irish oaks showed evidence of a severe environmental downturn between 535 and
550 AD, which Mike Baillie thought was likely to have been caused by another encounter between the Earth and the
disintegrating nucleus of the giant comet, proto-Encke. A team led by Cardiff University astronomer, Derek Ward-Thompson,
similarly concluded that a cometary encounter was the probable causal mechanism. On the other hand, in his 1995 book,
Catastrophe, David Keys, an archaeology journalist, attributed the events of the time to a massive explosion of Krakatoa,
larger than the one in 1883, whilst the American businessman and amateur archaeologist, Richardson Gill, in his book, The
Great Maya Droughts, published in 2000, suggested that the causal agent might have been a huge eruption of the Mexican
volcano, El Chich\u00f3n.
Climates eventually improved, but harsh conditions returned in the ninth century. Various annals of northern Europe tell of
famine, plague and civil war, against a backdrop of extremely cold winters, frequent earthquakes, strange lights in the sky a nd
a succession of comets. According to the annals, the Adriatic Sea froze in 860 AD, allowing merchants to travel to Venice by
horse and cart. Scandinavian tree-rings confirm that 860 AD was a particularly harsh year in a very cold century. Even the Nile
apparently froze over in 829 AD whilst, in Central America, another prolonged drought led to the final collapse of the Classic
Mayan civilisation.
Average temperature then generally increased for several centuries, before going into reverse as northern latitudes entered
the \u2018Little Ice Age\u2019, which only ended in the nineteenth century. During this period, there were several large volcanic eruptions
and arrivals of projectiles from space, yet none of them can be said to have changed the course of history to any significant
extent.
However, that outcome seems to have been far from inevitable. Take for instance the \u2018Tunguska event\u2019 in Siberia in 1908,
when a 50 metre extraterrestrial body exploded in the atmosphere, releasing energy equivalent to 15 megatons of TNT, i.e.
around 750 times more powerful than the Hiroshima bomb. Like the Mount St Helens eruption of 1980, this occurred in a
sparsely-populated region, so there was little loss of human life, but an area the size of Belgium was devastated.
Had the projectile arrived just four hours later than it did, it would have wiped out St Petersburg, and the history of the
twentieth century could have been very different. At the time, St Petersburg was the political centre of Russia, with Tsar
Nicholas II becoming increasingly unpopular and events taking place which eventually led to the October Revolution in 1917.
Again, had the projectile exploded over the sea, it could have produced a tidal wave to devastate coastal regions. And an
impact event on this scale can be expected to occur every century or so.
What about the effects of a less frequent but even more dangerous impact, by a larger body? What would have happened had
the Tunguska projectile been 10 km in diameter, like the one which struck Mexico 65 Myr ago? Would t he human race have
survived? And even if a few small populations had managed to cling on to existence, what sort of world would they now be
living in?
Conclusions
Now that we are aware of the threat from space, and from within the Earth, we need to understand the part they played in
past catastrophes. If we are to try to protect ourselves from the possibility of such catastrophes occurring again, we need t o
know exactly what caused them. If a catastrophe resulted from a massive volcanic eruption, then did something trigger this,
and were there any warning signs? If a catastrophe resulted from an extraterrestrial impact, then did this occur in isolation , or
was it part of an encounter with a cluster of comets or cometary fragments? What changes in terrestrial processes could be
stimulated by the shock of such an impact? And what about other potential causes of catastrophe, including wandering planets?
Regardless of what may or may not have happened during the Bronze Age, the notion that wandering planets may have
contributed in some way to a number of mass extinction episodes is a perfectly plausible one. The orbits of the giant planets
are now known to be on the margins of stability, and it has been suggested that changes in the orbit of Jupiter may have
disrupted the main asteroid belt during the Late Permian and Late Cretaceous periods. On the other hand, what about those
episodes of mass extinction which were caused by an interplay of terrestrial factors, producing anoxic oceans and other
hazardous environments, apparently without the direct involvement of any catastrophist mechanism? Can any pattern be
detected which could help with prediction of the future?
As with many situations, knowledge is of paramount importance. Only if we know with reasonable certainty what happened
in the past, and have developed a good appreciation of all actual and potential agents of destruction, can we start to addres s the
issues. To produce the best answer to threats against the future of our civilisation, we must full y understand the nature of the
problem. Never have there been more catastrophe-related issues to discuss, and never has it been clearer just how vital it is that
we do so, setting aside all other considerations in a single-minded search for the truth. Charles Lyell\u2019s dictum, that the present
is a key to the past, has served us well for over a century but, perhaps, there is now a need for it to be re -cast. In a very real
sense, the past could be the key to our future.
For further details and references see T. Palmer, Perilous Planet Earth, Cambridge University Press, 2003<\/p>\n","protected":false},"excerpt":{"rendered":"
Perilous Planet EarthTrevor PalmerText of a Talk Presented to the Society for Interdisciplinary Studies, Redhill, Surrey,24 September 2004Historical PerspectiveThroughout the first half of the twentieth century, the gradualistic paradigm, championed in the previous century by CharlesLyell and Charles Darwin, had seemed beyond challenge. As envisaged by Darwin, biological evolution proceeded in a slowand stately fashion, […]<\/p>\n","protected":false},"author":11,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[5322],"tags":[],"class_list":["post-47690","post","type-post","status-publish","format-standard","hentry","category-archive"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/atlantipedia.ie\/samples\/wp-json\/wp\/v2\/posts\/47690","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/atlantipedia.ie\/samples\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/atlantipedia.ie\/samples\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/atlantipedia.ie\/samples\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"https:\/\/atlantipedia.ie\/samples\/wp-json\/wp\/v2\/comments?post=47690"}],"version-history":[{"count":1,"href":"https:\/\/atlantipedia.ie\/samples\/wp-json\/wp\/v2\/posts\/47690\/revisions"}],"predecessor-version":[{"id":47691,"href":"https:\/\/atlantipedia.ie\/samples\/wp-json\/wp\/v2\/posts\/47690\/revisions\/47691"}],"wp:attachment":[{"href":"https:\/\/atlantipedia.ie\/samples\/wp-json\/wp\/v2\/media?parent=47690"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/atlantipedia.ie\/samples\/wp-json\/wp\/v2\/categories?post=47690"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/atlantipedia.ie\/samples\/wp-json\/wp\/v2\/tags?post=47690"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}