Archeology - Kobres, Bob - Comets and the Bronze Age Collapse

Comets and the Bronze Age Collapse by Bob Kobres

This article was published by the Society for Interdisciplinary Studies in the CHRONOLOGY AND CATASTROPHISM WORKSHOP 1992, number 1, pp.6-10, ISSN 0951-5984

. . . and from heaven a great star shall fall on the dread ocean and burn up the deep sea, with Babylon itself and the land of Italy, by reason of which many of the Hebrews perished, . . . Be afraid, ye Indians and high-hearted Ethiopians: for when the fiery wheel of the ecliptic(?) . . . and Capricorn . . . and Taurus among the Twins encircles the mid-heaven, when the Virgin ascending and the Sun fastening the girdle round his forehead dominates the whole firmament; there shall be a great conflagration from the sky, falling on the earth; Are these lines from Book V of the SIBYLLINE ORACLES eschatological nonsense? Contemporary astronomical evidence suggests a historic basis for words describing cosmic calamity. British astronomers, Victor Clube and Bill Napier, in THE COSMIC WINTER (1990) and other recent works, provide students of the past with newly discovered celestial clues which indicate that Earth has been periodically pelleted with comet fragments throughout the Holocene period. The evidence for the break-up of a large (> 50 km), short period (approximately 3.3 years), Earth-orbit-crossing comet is substantial and should be considered as hard as anything a trowel might turn up. What astronomical information cannot convey is the actual effect these periodic bombardment episodes had on human culture; only further digging and sifting will illuminate that aspect. Some of what can be uncovered has been buried by prior premise and so can be brought to light by review of literature published over the years. For instance, the oracles quoted above are from a 1918 translation of the "Sibylline" by H.N. Bate. Further into Book V these lines appear: And then in his anger the immortal God who dwells on high shall hurl from the sky a fiery bolt on the head of the unholy: and SUMMER SHALL CHANGE TO WINTER IN THAT DAY. Bate notes that Book VIII contains a parallel passage with winter being changed to summer--fortunately he did not feel compelled to "correct" the lines above as others have. For example: And then the imperishable God who dwells in the sky in anger will cast a lightning bolt from heaven against the power of the impious. INSTEAD OF WINTER THERE WILL BE SUMMER ON THAT DAY.

This comes from OLD TESTAMENT PSEUDEPIGRAPHA (vol. 1) published in 1983. Not only has the passage been rationalized (If God throws down fire it should get hotter, right?), but, a fiery bolt now has become a lightning bolt. Evidence of impact induced cold is valuable in gauging how energetic a past fall was. Based on nuclear winter studies, a cosmic collision would need to impart at least the energy equivalent of a thousand megatons TNT into the environment to produce such an effect. A number of cultures retained stories of impact induced winter. Most telling of such lore this author has read are these amazingly informative tales of the Yakuts: [note that the CH in brackets below is printed in the reference as a "c" with a diacritic "v"] [CH]OLBON . . . is said to be "the daughter of the Devil and to have had a tail in the early days". If it approaches the earth, it means destruction, storm and frost, even in the summer; . . . [CH]OLBON, the daughter of the Devil is a beautiful girl ... she is the bride and the sweetheart of Satan's son ÜRGEL (Pleiades). When these two stars come close to one another, it is a bad omen; their eager quivering, their discontinuous panting cause great disasters: storms, blizzards, gales. When they unite, fathom deep snow will fall even in the summer, and all living beings, men, animals and trees will perish . . . Both folk memories were recorded by ethnographer V.L. Serosevsky, the first in 1877, the next in 1885. The Yakuts identified Venus as colbon; however, as a later student of this culture, G.V. Ksenofontov, observed: The Yakuts have two words for the "star": SULUS and [CH]OLBON. The first means simply "star", the second refers to stars that change their place in the sky, sometimes appearing and disappearing. Nowadays, however, it no longer--or very seldom--refers to other planets than Venus and has almost become its name. Yet, as we have seen, in legends also other [CH]OLBONS (i.e. planets) are mentioned. What is remarkable about these particular tales is the conjunction of several pieces of information. From these lines we gather that a comet ([CH]OLBON with a tail) came close enough to influence weather on Earth--i.e. deadly storms, frost and deep snow in summer. Also, we are told that this is most likely to occur if the comet appears close to the Pleiades. In short, these legends accurately describe what can now be inferred from astronomical data on comet Encke and the ring of debris its progenitor strew about the Sun. As the above example suggests, contemporary researchers need to be wary of assuming our predecessors' folk memories of astral events relate to bodies familiar to our time. There is considerable reason to suspect that the majority of the planets namesakes were comets--probably of the Encke family.

A conventional view comes from W.M. O'Neil's TIME AND THE CALENDARS (1975): The word planet comes from the Greek PLANETES, the wanderers; these seven celestial bodies moved among the fixed stars. The Babylonians had a more picturesque name, BIBBU, the wild sheep, as these bodies broke through the fixed formation in which the tame sheep crossed the sky. To call into question Greek continuity of planet identity I refer to Leonardo Taran's work on the "PseudoPlatonic" Epinomis (1975) where in commentary on lines 986 A 8-987 D 2 Taran states: Having previously proved to his own satisfaction that all the heavenly bodies are the greatest divine living beings and having pointed out that they are not yet honored as gods, the author explains who these visible gods are and why they are not honored in Greece. They are the eight interrelated sidereal revolutions and the heavenly bodies which travel on them, for they are all gods of the same kind. And the contemplation of this divine cosmic order is what will make a man happy both in this life and in the next. But the lack of this wisdom in Greece is due to ignorance of the true paths of the planets, a knowledge which comes from the Orient and which must be incorporated into our laws. That the knowledge of the planets comes from the Orient is to be seen in the very fact that the planets lack proper names and are called after the (traditional) gods, for this kind of appellation is due to the barbarians who first discovered the planets. The Epinomis, which dates from around the 4th century BCE, is the earliest extant record of Greek planet names; each is given as "the star of": Cronos, Zeus, Aphrodite, etc. Clearly the planets did not inspire the earlier stories which championed these gods. The mythology associated with these names certainly better describes the break-up of a comet with an orbit that crossed Earth's path than the monotonous behavior of planets. As for the BIBBUS, as well as the Oriental influence alluded to above I call attention to J.K. Bjorkman's article in METEORITICS (1973) which deals with much earlier texts: We move now to a discussion of a word which probably refers to comets, BIBBU. . . BIBBU has a variety of astromantic and non-astromantic meanings. There is a lengthy omen text, the 56th tablet of Enuma Anu Enlil, which deals with various features of the BIBBU, and some of these seem to describe comets. For example: If a BIBBU continues one day, two days in the sky and does not disappear: If three or four BIBBUS rise one after the other at sunrise The latter text might refer to a comet which has broken up into three or four comets . . . . There are many more references to BIBBU, but in them the translations "unspecified planet" or "meteor" could be proposed.

Confusion of planet terminology is also evident further to the east as can be demonstrated by James Legge's translation of a passage concerning the emperor Kwei in the ANNALS OF THE BAMBOO BOOKS: In his 10th year, the five planets went out of their courses. In the night, stars fell like rain. The earth shook. The E and Loh became dry. With astronomical evidence in mind a simplified, but testable, hypothesis of Bronze Age collapse would involve accepting the legend of Phaethon as an event inspired myth, as Plato contended it was, and also giving credence to stories of protracted winter in the aftermath of celestial "battles," such as the Ragnarok. During a close approach to a massive object like our planet a comet would be gravitationally disrupted (Phaethon's disentegrating chariot) independent fragments would then further break to pieces as they entered Earth's atmosphere. This debris, of various shapes and sizes, would scatter widely along the path of the fall, each piece harboring energy in proportion to its mass. The "footprint" of this event could have included some of: southern Europe, the Mediterranean, the Near East, and Northern Africa. Damage, however, would not be uniform throughout this area. If the disintegrating objects were traveling south of east, as the Phaethon story implies, the more massive fragments would travel farther and release their greater energy, explosively, lower in the atmosphere toward the southeast end of the elliptical area directly affected by the fall. In other words, the Near East would be more heavily damaged than southern Europe. A survey scaling intensity of site destruction might reflect this aspect, i.e., vitrification of soil and building materials might occur below lower altitude multi-megaton blasts. Secondary effects of a large impact event would include: a spottily enhanced C-14 environment, making this means of dating unreliable to confirm or refute simultaneous destruction of disparate sites; a large production of oxides of nitrogen yielding dangerous ozone depletion, perhaps giving a survival advantage to darker skinned people in the aftermath, particularly in equatorial regions; acidic precipitation from the above-mentioned atmospheric chemistry; and, in the higher latitudes, impact winter, caused by suspended dust and soot. All of these phenomena would leave evidence which careful field work could reveal. Some indicators may already be evident, such as the abandonment of many long settled sites, a large southward movement of people from the higher latitudes, and a steep, long-term (1159-1140 B.C.) decline in the annual growth of Irish bog oak that stands out in the 7,272 year long dendrochronological record, based on this species of tree. [Baillie and Munro (1988)] Definitive evidence of impact, however, can only come from a detailed analysis of debris directly overlying destruction sites. I urge archaeologists working on this time period to diligently collect dust and debris from cracks and crevices where violent destruction is apparent. In 1992 the current Greenland ice coring project should be complete. If a large impact occurred around 3200 years ago a significant nitric acid spike will be evident in these ice core samples. Several cores are being drilled simultaneously, so the chance of finding debris in association with the nitric acid signal should be good. An element profile on this material could then be

compared with results on debris extracted from terminal Bronze Age sites. If these match, not only will there be confirmation of a violent natural catastrophe, we will also have gained a rather precise gauge of when the disaster took place. Astronomical evidence indicates our ancestors viewed a much more active sky than we. A seemingly nonsensical notion, such as Athena being born fully formed from the head of Zeus, becomes understandable as a description of comet fragmentation. Human belief systems have been greatly influenced by the phenomena attending the progressive break-up, over thousands of years, of this large comet. The idea of a wrathful sky god or star positions influencing events on Earth are legacies of this influence. Many astronomers believe the 1908 Tunguska impact was from a small piece of Comet Encke. This 15 to 30 megaton event leveled 2000 sq km of dense Siberian forest, but left no crater. Certainly there have been many damaging falls witnessed by people during the 15,000, or more, year period of the comet's fragmentation history. The terminal Bronze Age event was probably just one of several very energetic impacts which likely occurred in this time span. Our less than seven hour separation from a collision with a near-Earth asteroid (1989FC) in March of 1989 underscores the fact that contemporary civilization could be thrown into a dark age by natural catastrophe. Had 1989FC encountered Earth it would have introduced the energy equivalent of more than 2,000 megatons TNT into the environment, with little or no warning. The object was discovered on photographs days after the close pass. In 1937 an even larger object, Hermes, came almost equally near Earth. Neither of these asteroids is likely to be related to the break-up of the recent large comet referred to above. The estimated population of Earth-orbit-crossing objects greater than half a kilometer in diameter is over 2,000 and its members are from various sources. Obviously our planet gets hit fairly often. What the recent large comet did was increase the likelihood of collision and establish a visible cause/effect relationship in the minds of our ancestors. The association of disaster (etymologically, dis - evil; aster - star) with comets eventually became generalized beyond direct causal links, giving science oriented investigators reason to classify this ubiquitous notion as mere superstition. Scientific efforts to understand the past were thus rendered purblind to a highly influential natural phenomenon. It is technically feasible to prevent future impacts by altering the orbits of threatening objects. Unfortunately, there is little widespread support for such an Earth Defence Initiative (EDI) due, in part, to the general belief that humanity has not, in the past, been harmed by impact events. Archaeologists can play a key role in justifying an EDI by digging in to set the record straight. Though gaining a detailed understanding of the effects such episodic impacts had on humanity will take some time, incorporating recent astronomical evidence can provide immediate boons to our comprehension of past cultures.

The fortunate find in the seventies, at Mawangdui, China, of a Han dynasty silk comet atlas sheds considerable light on earlier enigmatic motifs. Most illuminating is the drawing, described by text on the artifact as a long-tailed pheasant star. This rendering of a jetting comet viewed down its axis of rotation has a considerable history, and, as a motif, appears on artifacts found in most areas of the world. The artist who illustrated this silk twenty-two hundred, or so, years ago was not likely a first-hand observer. What is produced here is a schematic of received comet caricatures with claims that specific things will happen if a represented type appears. The pinwheel-like image is unique to the compilation in that an omen is given for an appearance in each of the four seasons, implying that this comet was seen more often than the others represented. This may illustrate a frequently viewed aspect of comet Encke which has a 3.3 year orbit and rotational axis that occasionally points toward Earth. [Whipple, F. 1985]

Important in understanding ancient oriental lore is learning that this motif was associated with the pheasant (divine bird in China) which is frequently mentioned in the Chinese classics. The link between the spinning cross and birds is evident on artifacts from many cultures. Perhaps the association of the Sanskrit term "svastika" with this symbol can be linked to the Astika Parva in the MAHABHARATA which relates the birth of a cosmic bird par excellence--Garuda. This fabulous winged deity had a radiance like the Sun, could change shapes at will, and destroyed other gods and kings by casting down fire and stirring up storms of reddish dust which darkened the Sun, Moon and stars. Clearly Garuda was symbolic of an Earth approaching comet. The bird-comet connection is even more obvious in the Jamva-khanda Nirmana Parva of the MAHABHARATA which describes a fierce fowl with but one wing, one eye, and one leg, hovering in the night sky. As this bird "screams" and "vomits blood": All the quarters of the earth, being overwhelmed by showers of dust, look inauspicious. Fierce clouds, portentous of danger, drop bloody showers during the night. Rahu of fierce deeds is also, O monarch, afflicting the constellation Kirtika. Rough winds, portending fierce danger, are constantly blowing. The mention of Rahu, the demon of eclipse, which originally had four arms and a tail that was severed by Vishnu to become Ketu (comet) is interesting in that the demon is here darkening Kirttika (the Pleiades) in the month of Karttika (latter half of October, through mid November), for the tale goes on to relate that: . . . in course of the same month both the Moon and the Sun have undergone eclipses on the thirteenth days from the day of the first lunation. The Sun and the Moon therefore, by undergoing eclipses on unusual days, will cause a great slaughter of the creatures of the earth. Meteors, effulgent like Indra's thunder-bolt, fall with loud hisses . . . People, for

meeting together, coming out of their houses with lighted brands, have still to encounter a thick gloom all round . . . From the mountains of Kailasa and Mandara and Himavat thousands of explosions are heard and thousands of summits are tumbling down . . . Fierce winds charged with pointed pebbles are blowing, crushing mighty trees. In villages and towns trees, ordinary and sacred, are falling down, crushed by mighty winds and struck by lightning. This is, without doubt, a mythological record of an intense meteor storm from the still active Taurid stream which presently peaks around the first of November and appears to radiate from near the Pleiades star cluster. The un-airworthy bird associated with this meteor bombardment could have been comet Encke which until recently was thought to be the sole source for the Taurid meteors. However, the discovery of other large contributors which are now dark but were once active comets rules out a positive identification.

Another interesting aspect of this folk memory which might shed some light on why the rolling cross motif is linked to birds is the image of a one-legged fowl. This is also a characteristic of the Chinese divine pheasant which was closely associated with the fabulous, lame, raven-beak-nosed emperor, Yu, who could transform himself into this pheasant or a bear. One of Yu's enemies, the Owl, who invented thunder and lightening was also one-footed. [Lonsdale, S. 1982, Barnard, N. 1972, 1973]

In a less artificial environ animal tracks speak strongly to people and convey much about the creature which left them. Thus a bear, bird or any animal which made impressions on the ground could be symbolically represented in total by drawing these marks. I suggest that the jetting comet, to some cultures, looked like a bird's foot and, as a motif, represented a divine fowl. This can explain why the not very bird-like drawing on the Han silk is captioned as a pheasant star. Chinese lore upholds such an interpretation as Ts'ang Chieh, the four eyed legendary inventor of writing, derived his inspiration to create written symbols from noticing the marks of birds' feet in the sand. His ancient style is known as niao chiwen--"bird foot-prints writing." [MacCulloch, C.J.A. 1928]

Symbolic bird tracks, unrecognized as such, appear on objects unearthed by Heinrich Schliemann from Hissarlik in Asia Minor. Artifactual support for this contention comes from petroglyphs found in the south-western United States which Pueblo people identify as roadrunner (a type of cuckoo) tracks and identical renderings found by Schliemann. [Morphy, H. 1989] The close association of these two distinctive crosses on artifacts from Schliemann's Troy could be considered coincidental and not necessarily avion-inspired were they found out of context, however, in Schliemann's words:

In treating now of the various kinds of potteryof this third city, I begin with the owlfaced idols and vases,

and I would repeatedly call very particular attention to the fact, that the idols, of which I collected about 700, are all of the same shape; that they represent in the rudest possible outlines a female form; and that, therefore, they cannot but be copies of the ancient Palladium, which was fabled to have fallen from heaven with joined feet.

From Mari

Owls, like cuckoos, have zygodactylous or semizygodactylous (outer toe reversible) feet. Obviously these "Trojans" had an elaborate belief system which focused on the activities of a nonterrestrial bird of the night. With this in mind, a re-examination of artifacts recovered from Hissarlik could be quite revealing.

Another aspect of comets which is evident in ancient lore involves shape shifting. A comet is three dimensional and could appear as quite a different animal when viewed from a different angle. For instance, allowing that a foot-print signifies the creature, the fabled ability of Yu (mentioned above) to transform into a pheasant or bear can be easily understood as a radial view distinguished from an axial view of the same comet. Comets can also change spontaneously; a gas emitting area could become dust covered and extinguish a jet, a piece of the comet could break away, creating another comet, perhaps initially more flamboyant than its parent. Our ancestors' stories speak of these weakening gods and fantastic births; however, until now, our ears heard only gibberish. Another motif which is found around the world is the concentric circle. Astronomers, with the aid of a telescope, have reported, and drawn pictures of, comets which exhibit concentric rings, so it is likely that some of these ancient renderings, often pecked in stone, represent comets. There is, however, probably another phenomenon more often represented by these ancient bull's-eyes--a bolide storm. Fred Whipple, the astronomer who theorized in 1950 the now proven structure of comets, calculates that the night time Taurids have been a feature for 5,000 years. It now takes Earth about three months (midSeptember to mid-December) to traverse this band of debris. Earlier in its history, as the progenitor of comet Encke was creating it, this debris ring had to have been more dense. As Earth passed through the mess, it no doubt collected a considerable amount of dust. The night time Taurids are known for frequent bolide activity. Large, vaporizing meteoroids (bolides) in an atmosphere loaded with comet dust will produce unusual visual effects. Refraction, reflection, and possibly secondary emission come into play as a sizable object splashes into an aerosol laden atmosphere compressing molecules of gas against motes of dust in its bow-shock wave until--BOOM -- the object vaporizes, illuminating the multiple layers of compression separated gas and debris. From the ground this might look as if a god threw a pebble in the sky pond. Quite likely a large sector of the sky would be filled with such phenomena. Though the intensity would vary from year to year our ancestors, no doubt, expected a rather disconcerting light show on an annual basis. Striking evidence for this contention comes from well-preserved Neolithic observatories in Ireland. Martin Brennan (1983), who spent over a decade investigating these structures, published a wonderful documentation of their features. Though he assumes them to be a product of solar worship, his research is thorough and includes mythological references to these megalithic works--most intriguing from the standpoint of this discussion is Tara. Brennan states that: Tara lies 10 miles southwest of Newgrange and, like Newgrange, it is steeped in ancient myth and tradition. It has always been associated with Samhain, the Celtic observance of the year's turning in November, and this event is well documented. Mythologically, the mound also has associations with the Tuatha De Danann, or the "Lords of Light." They arrive from the air and cast a darkness over the sun for three days. This neolithic observatory is aligned, according to Brennan, to cross-quarter days November 8 and February 4. The carved stone within this megalithic structure depicts concentric circles similar to the earth works evident in the aerial photograph of Tara shown.

Incorporating astronomical evidence of a recent giant short period comet into our attempt to understand past cultures is essential for an objective interpretation. Bobk 91

BIBLIOGRAPHY

Armstrong, Edward A. (Ed.) THE FOLKLORE OF BIRDS. Dover Publications, Inc. NY, 1970. Baillie, M.G.L. & Munro, M.A.R. "Irish tree rings, Santorini and volcanic dust veils." NATURE vol. 332 24 March 1988 (pp. 344-346). Barnard, Noel (Ed.) EARLY CHINESE ART AND ITS POSSIBLE INFLUENCE IN THE PACIFIC BASIN. vol. 1 Intercultural Arts Press, NY, 1972 (pp. 118-121, 150-151). Barnard, Noel. THE CHU SILK MANUSCRIPT (Translation and Commentary, part 2) Australian National University, Canberra, 1973 (pp. 122-156). Bate, H.N. THE SIBYLLINE ORACLES Books III-V MacMillan Company, NY 1918 (p. 107). Bjorkman, J.K., "Meteor and Meteorites in the Ancient Near East" METEORITICS 1973 vol. 8, (pp. 91132). Brennan, Martin. THE STARS AND THE STONES. Thames and Hudson Inc., NY 1984 (pp. 14-15, 120121). Charlesworth, James H. OLD TESTAMENT PSEUDEPIGRAPHA (vol 1) Doubleday, Garden City, NY 1983 (p. 400). Clube, Victor and Napier, Bill. THE COSMIC WINTER Basil Blackwell, Inc. Cambridge MA 1990. Dioszegi, V. POPULAR BELIEFS AND FOLKLORE TRADITION IN SIBERIA (English translation by Dunn, S.P.) Indiana University,Bloomington, 1968 (pp. 485-496). Kobres, Bob. "Meteor Defense" WHOLE EARTH REVIEW No. 56 Fall 1987 (pp. 70-73). Legge, James. THE CHINESE CLASSICS (vol. 3) Hong Kong Univ. Press, Hong King 1960 (p. 125).

Lonsdale, Steven. ANIMALS AND THE ORIGINS OF DANCE, Thames and Hudson Inc., NY, 1982 (pp. 169-181). MacCulloch, C.J.A. Canon, John A. (Ed.) MYTHOLOGY OF ALL RACES. vol. 8 ("Chinese Mythology" Ferguson, John C.) Marshall Jones Co. Boston, MA 1928 (p. 31). Morphy, Howard (Ed.). Animals into Art (ONE WORLD ARCHAEOLOGY; vol. 7) Unwin Gyman Ltd., London, 1989 (chapt. 11 Schaafsma, Polly). O'Neil, W.M. TIME AND THE CALENDARS. Sydney Univ. Press, Sydney 1975. Roy, Pratap Chandra. THE MAHABHARATA, Munshiram Manoharlal, New Delhi, 1973 (vol. 1 section 13-58, vol. 5 section 2-3) Schliemann, Henry. ILIOS Harper & Brothers, Franklin Square, NY, 1881 (pp. 334-353). Taran, Leonardo. ACADEMICA: PLATO, PHILIP OF OPUS, AND THE PSEUDO-PLATONIC EPINOMIS American Philosophical Society, Philadelphia, PA, 1975 (p. 294). Whipple, Fred L. THE MYSTERY OF COMETS Smithsonian Inst. Press, Washington, DC 1985, (pp. 163-167).

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A cosmic trail with destruction in its wake by Nick Nuttall Copyright 1990 Times Newspapers Limited The Times, May 24, 1990, Thursday

Over the next few weeks the Taurid stream, a procession of vast cosmic rubble and dust that snakes around the Sun and out towards Jupiter, will swing through Earth's orbit for the first of its bi-annual crossings. Within the stream are probably thousands of bodies including asteroids, mountain-and island-sized boulders, smaller meteoroids, Encke's Comet and assorted fragments of celestial refuse. The exact number, size and location of objects, however, remains a mystery and according to Dr. Mark Bailey, research Fellow in astronomy at Manchester University, it is likely that for every object which is confirmed, there are nine others that have so far eluded detection. All that is certain is that the rubble, believed by some astronomers to have been formed by a collision in the asteroid belt of a defunct comet which was captured by the solar system up to 30,000 thousand years ago, will bisect Earth's orbit in late June and again in November. According to astronomers such as Dr. Victor Clube, of Oxford University's Department of Astrophysics, the coming and goings of the Taurid stream should be a source of concern to politicians, planners and anyone who cherishes life on Earth. A ''catastrophist'', Dr. Clube is one of many astronomers who are convinced that within this celestial procession lie the seeds of mass destruction an Armageddon of biblical proportions. ''The matter requires urgent attention. It is crucial that everyone is woken up to the danger,'' Dr. Clube says. The chilling scenario envisaged is of Earth and one of the 46,000mph objects in the Taurid stream colliding during one of the orbital crossings. Dr. Clube says: ''It is analagous to a nuclear war with a megatonnage of the same order and all the effects of nuclear war with debris from the impact causing sunlight to be blocked causing a Dark Age or Ice Age.'' He has coined the phrase ''Multiple Tunguska Bombardment'' to describe the worst nightmare which, he believes, will eventually happen. Tunguska refers to a Siberian River near which, in June 1908, a 100 yard body from the Taurid stream ploughed into Earth, exploding and devastating an area 25 miles wide with the impact of a 20-megaton bomb. Fortunately the encounter occured in an unpopulated part of the globe but if the impact had been on

London it would have devastated the city, killing millions. The Tunguska event may have been only a chance occurence. Yet, according to Dr. Clube and Dr. Bill Napier, of the Royal Observatory in Edinburgh, whose book Cosmic Winter is published next month, the history of Earth is littered with subtle evidence that cosmic debris have consistently intervened, often with catastrophic consequences. One of the most popular theories to explain the sudden demise of the dinosaurs is that, 65 million years ago, a huge asteroid ploughed into the planet, triggering either a nuclear-style winter or huge fires. This popular theory was given a boost only last week when scientists at the University of Arizona reported the discovery of an apparent 180-mile-wide crash site in the Caribbean of an asteroid six miles wide. They claim this could be linked with the great reptiles' extinction. Dr. Clube ascribes other events including the Old Testament story of Noah and his Ark to a Dark Age linked with colliding heavenly bodies. He also believes that climatic changes, including fears of present global warming, may have a cosmic component. There is sufficient evidence, he says, to indicate that collisions happen within centuries and millenniums rather than millions and billions of years, with multiple encounters more likely than sceptics claim. Dr. Clube emphasizes that predicting when a bombardment may occur is impossible without more scientific evaluation of the Taurid stream. ''We are probably a little safer at the moment because the intersecting orbits are far away. But we are on the inward run and in 500 years we will start getting close again,'' he says. According to Dr. Clube, the last time that the stream was closest within Earth's orbit was in the first millennium BC, from about 500BC up to 0AD, the time of Christ. It is vital to overcome complacency about the threat from cosmic debris, he says. This complacency is relatively new, as pagan and ancient civilisations such as the Babylonians were firm believers in the threat of of cosmic destruction. Part of the blame for this complacency rests with the breakup, in 1845, of Comet Biela without any easily visible effect on Earth. ''This rather relaxed attiude to comets, which has persisted to the present day, helped turn 19th century opinion against a prevailing catastrophist view of evolution,'' Dr. Clube says. ''Indeed, the eventual disintegration of Comet Biela into dust made it no longer out of place for biologists and geologists to explain evolution in processes that were non-violent and slow-acting.'' ''In short, it became fashionable to assume that the world is safe when in fact multiple Tunguska bombardments, releasing around five-thousand megatons, the equivalent of a full-scale nuclear war, may happen at intervals of about 1,500 years, producing a Dark Age,'' he says.''To suggest the

planet is safe is absurd.'' The Oxford astrophysicist is not alone in his views. Similar concerns were echoed last week by the respected American Institute of Aeronautics and Astronautics (AIAA). The institute is calling for studies aimed at defending the Earth from asteroid attack, including the possible redeployment of nuclear weapons to shatter incoming celestial bodies. The call comes in the wake of thawing East-West relations and what is being claimed as a recent, potentially disastrous near-collision. Last year, 1989 FC, a cosmic boulder bigger than an aircraft carrier, passed within 400,000 miles of Earth, a mere whisker in astronomical terms, before being noticed by astronomers. ''Such an object could cause a disaster of unprecedented proportions if it had struck. Although the probability is very small, its consequences in terms of the casuality rate could be enormous,'' the institute argues in a paper it released about the problem. Apart from putting nuclear warheads on standby for intercepting and shattering asteroids, the institute is calling for studies into power units that could attach and divert the celestial boulders away from Earth. ''We have the technology needed to detect and track such an object and possibly to divert if from an impending impact. We would be derelict if we did nothing,'' the institute says. Dr. Clube is hoping to get access to an infra-red telescope to study the Taurid stream during the November crossover. In 1983, a satellite revealed what appeared to be dust following Comet Encke, but some scientists, including Dr. Clube, now believe that this contains the single large missing body, perhaps as large as 20 miles wide, shrouded in dust and boulders. The best chance of detecting the defunct comet might come in 1994 when the American National Aeronautics and Space Administration (Nasa) is expected to launch the infra-red telescope, ISO. Dr. Bailey says: ''We are learning more about these objects almost every week. We are realizing that there are quite a large number of fairly large objects, ranging in size from just a few hundred yards to six miles across, which are in Earth's collision orbit.'' Along with Dr. Bailey, Dr. Clube supports the institute's call for improved monitoring. But both British astronomers are concerned at suggestions of shattering incoming asteroids. They believe that there is the danger that by solving one large threat, it may create scores of smaller ones. Cosmic Winter by Dr. Victor Clube and Dr. Bill Napier. Published in June by Basil Blackwell (Pounds 16.95). The Origin of Comets by Dr. Mark Bailey, Dr. Victor Clube and Dr. Bill Napier. Pergamon Press.

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An excerpt from The Metamorphoses by Ovid, as translated by A. E. Watts. University of California Press, 1954

The Sun-god Phoebus is speaking to Phaethon: Five zones there are: your course, confined to three, The farthest north and south must never see. Next, share your heat between the earth and sky; Press not too low, nor set your course too high. Heaven's halls will kindle, if too high you stray; Too low, the earth: your safety lies midway. Nor swerve, where on the right the Snake is seen, Nor left to the Altar: steer your course between. The rest is Fortune's: be her favor shown, And better wit to guide you than your own. But see: dank night upon the western shore

Has touched the waymark: we can stay no more. Dawn breaks; and while I speak, the shades disband. We are awaited: take the reins in hand. Or can you still, unbending as you are, Relent, and take my counsel, not my car; While yet your feet a firm support can feel, Not what you blindly wish, the treacherous wheel? Why ask for danger? Be content to see, And leave the lighting of the world to me."-But Phaethon, with words of thanks that jar Upon his father's ears, has climbed the car; Consumed with joy, the reins within his hands, The slender boy in proud possession stands. Meanwhile the team, Dawn, Blaze, and Fire, and Flame, Whose scorching breath in fretful whinnyings came, Beat on the barriers. Tethys little knows On what predestined path her grandson goes. She draws the bolts, and lets the barriers fly, And gives the steeds the freedom of the sky. Then, tearing up the trail, wing-borne, they beat The air, and cleave the clouds with flying feet; Outrun the winds; and, feeling not their freight,

Wonder to miss the yoke's accustomed weight; And as a ship, unladen, lurching rides, And all too light, goes tottering o'er the tides, The car, that lacked its customary load, Bounced up, as if unridered, from the road; And sensing this, the steeds run wild, and stray Clean from the course, and throw restraint away.

Fear on the driver fell; too quick to gain, Too slow to learn the handling of the rein, He lacks besides all knowledge of the way, And if he knew, the team would not obey. Then first the Bears felt heat, and tried in vain To pass their bounds, and plunge beneath the main; And near the pole the numbed innocuous Snake Felt, with the warmth, his wicked passions wake. Bootes too, they say, made off in dread, Though with slow steps his lagging wain he led. Now when the luckless boy with downcast eye Beheld the lands deep, deep, beneath him lie, His color fled; his knees with sudden fright Shook, and his eyes went dark with too much light.

He wished his father's team well left alone, His prayer unanswered, and his birth unknown; Wished Merops for his sire (ambition new) As like a ship before a storm he flew, Whose helmsman, pressed too hard, resigns his care, And leaves the craft to providence and prayer. What now? He scans the sky with measuring mind; Much heaven before him lies, no less behind; Now to the west (the goal that fate denies), Now backward to the east he turns his eyes. Palsied with doubt he stands, and turned to stone:

How rule the steeds, their very names unknown; How hold, how drop the reins? Now too appear Strange shapes that strew the skies afar and near, Huge beasts of prey: he sees and shakes with fear. There is a region, where the Scorpion draws The pincer pattern of his curving claws; With curling tail, and jointed legs each side, He spreads his limbs two constellations wide; And sweating with black venom, does not fail

To threat the tortures of his twisted tail. The driver saw: the vision chilled his veins; And as his senses swam, he dropped the reins. When on their backs the sagging leathers lay, The horses broke all bounds, and romped away; And where their lawless headlong motion led,

Through unknown realms of air unchecked they sped; And rammed the unswerving stars, and at their heels Through trackless wastes they dragged the rocking wheels; And now they soar aloft, and now they stoop By steep declines, and make an earthward swoop. The wondering moon beheld her brother's team Beneath her own, saw clouds go up in steam. From peak to loftiest peak the earth takes fire, And cracks and splits, as all its saps suspire. Grass wilts; and with their leaves the tree trunks flare; And cornfields feed the flame that leaves them bare. Small matters these--walled cities melt away; Whole tribes and peoples turn to ashes gray; The mountain masses with their forests burn:

Athos and Oete; Tmolus in his turn; And Taurus smokes upon Cilicia's shore; And Ida's many fountains gush no more; Cynthus and Othrys, Haemus, yet unknown, And Eryx burns, and virgin Helicon; Parnassus lifts his two candescent spires; And Etna streams with duplicated fires; Dindyma, Mycale, and Mimas glow; And Rhodope must shed her ancient snow; Not Scythia's native frosts can keep her free; Cithaeron, not his native sanctity; And Pindus burns with Ossa, mighty names, And mightier yet than both, Olympus flames; Cold Caucasus with conflagration shines, Air-piercing Alps, and cloud-capped Apennines. Thus Phaethon, where'er he turns his gaze, On every side beholds the world ablaze; And faint, and breathing air at furnace heat, He feels the car red-hot beneath his feet. Wrapped in a pitchy pall of blinding smoke, While cast-up ash and cinders sear and choke, He knows not where he is, nor whither bound,

Dragged by the horses where they choose the ground. Robbed, by the heat, of moisture, Libya's plain Turned then to desert, ne'er to bloom again; And as the sun-burned blood boiled up, they say,

The Ethiopian changed his skin that day. Then did the nymphs their loosened tresses fling, And weep their fill o'er every lake and spring. Thebes thirsts for Dirce, Corinth craves her cool Pirene, Argos Amymone's pool; And favored streams, 'twixt wide embankments pent, (Not saved thereby) with seething waters went: The steaming Tanais, wrapped in mists of heat; And old Peneus, and Ismenus fleet; Lycormas, rolling down his burning sand; And Erymanthus, in Arcadian land; And far Caicus, on the Mysian shore; And Trojan Xanthus, doomed to burn once more; Madcap Maeander, turning on his trail; Eurotas, wandering through Laconia's vale; Euphrates, big with Babylonia's fame; And Melas, and Orontes, were aflame;

Thermodon, Ganges, Phasis, Hister showed Their fires; Alpheus boiled, Spercheus glowed;

The ore that Tagus carried as he rolled, Now flowed itself, a stream of liquid gold; Cayster scalded, as they sailed along, The swans that filled Maeonia's banks with song; Old Nile in fear to earth's far corners fled, And hid his never rediscovered head; And where his sevenfold course should seaward stray, Lacking their streams, seven dusty channels lay. So the world o'er: Strymon in Thrace runs dry, And Hebrus; and beneath the western sky Rhine, Rhone, and Padus share the selfsame fate, With Tiber, whom his promised realms await. Earth gapes, and startling rifts of daylight show To king and consort in the world below. The sea contracts its bounds, and leaves a plain: Dry wastes of sand, where lately rolled the main; And hills break surface, that were sunk before, And make the sprinkled isles so many more. The fishes dive, and bow-backed dolphins dare

No longer leap, and take their wonted air; And lifeless seals, upturned, go drifting there.

Nereus himself, deep in his rock retreat, With Doris and her daughters, felt the heat; And thrice did Neptune from the waters raise His glowering face, and could not bear the blaze. But Mother Earth, with ocean ringed about, Her native springs within, the seas without (Since all her rivers sank within her womb, And sought again their antenatal gloom), Raised her fire-ravaged head, and with her hands Shielded her face; and as she shook the lands With vast convulsions, settled down a space, And held a lower than her wonted place; And thus appealed to Jove: "By fire," said she, "If 'tis my due to fall, and thy decree, Why lag thy lightnings? Let me fall, most high, By fire of thine, consoled, by whom I die." She scarce could speak, so hot the vapor smote: "These words," she sobbed, "are strangled in my throat. Ah, see how thick the burning cinder lies

On my charred hair, how thick on face and eyes. Is this my payment, this the wage you owe, That scarred and wearied, racked by plow and hoe, In fertile function through the year I go, Providing food for beasts with herbs benign, And grain for men, and incense for the shrine? Or grant that ruin justly falls on me, What of my brother and his realm, the sea? What guilt is his, that this, his lawful share, Shrinks, and extends the empire of the air? Nay, if our claims to pity pass thee by, Have feeling for thine own domain, the sky. Look well! the poles, which smoke already show, If sapped by fire, will lay your mansions low. See, Atlas is distressed, and much I fear His shoulders ill support the burning sphere. If seas and lands are wrecked, and heaven's high throne, We perish, back to primal chaos thrown. Put forth your care; what still survives the fire, Rescue, and save the sum of things entire." The sacred accents faltered: Earth could bear

No more the stifling smoke and parching air. She ceased, and sank within herself, and fled To caverns near the shades, and hid her head. Now Jove almighty made the gods attest (Him that had lent the car among the rest) What choice remained: to use his instant aid, Or see the worlds in grievous ruin laid; Then scaled the summit, whence his clouds are spread, His thunders shaken, and his lightnings sped; But found to hand ( all custom overthrown ) No clouds to spread, no rain to scatter down. He thundered; and a lightning-bolt he drew, And lancelike poised, with careful aim, and threw At Phaethon, and made his lease expire Of life and chariot, quenching fire with fire. The horses leap apart in frantic fear, Shake loose the reins, and wrench the traces clear; and bridles, spokes, and wheels dismembered lie, axle and shaft: the wreckage strews the sky; And Phaethon, his ravaged hair aflame, Down in a trail of radiant ruin came, As oft, when summer nights unclouded are,

There falls from heaven, or seems to fall, a star;

And Po, far distant from his native place, Received his fall, and cooled his burning face; And nymphs, that in the western waters dwell, Laid him to rest, and graved a verse as well: "Here Phaethon is laid, who sought to guide His father's steeds, and, greatly daring, died." The sun-god, broken by the piteous blow, Concealed his visage, sicklied o'er with woe; And suffered one whole day its course to run, If legend does not lie, without a sun. The fires, still burning, gave what light they could, And so from evil came some touch of good.

Phaethon article Bronze age article The content and opinions expressed on this Web page do not necessarily reflect the views of nor are they endorsed by the University of Georgia or the University System of Georgia.

Plato's Timeaus 21e--23b A full translation is available at this site.

[21e] "In the Delta of Egypt," said Critias, "where, at its head, the stream of the Nile parts in two, there is a certain district called the Saitic. The chief city in this district is Sais--the home of King Amasis,--the founder of which, they say, is a goddess whose Egyptian name is Neith, and in Greek, as they assert, Athena. These people profess to be great lovers of Athens and in a measure akin to our people here. And Solon said that when he travelled there he was held in great esteem amongst them; moreover, when he was questioning such of their priests [22a] as were most versed in ancient lore about their early history, he discovered that neither he himself nor any other Greek knew anything at all, one might say, about such matters. And on one occasion, when he wished to draw them on to discourse on ancient history, he attempted to tell them the most ancient of our traditions, concerning Phoroneus, who was said to be the first man, and Niobe; and he went on to tell the legend about Deucalion and Pyrrha after the Flood, and how they survived it, and to give the geneology of their descendants; [22b] and by recounting the number of years occupied by the events mentioned he tried to calculate the periods of time. Whereupon one of the priests, a prodigiously old man, said, "O Solon, Solon, you Greeks are always children: there is not such a thing as an old Greek." And on hearing this he asked, "What mean you by this saying?" And the priest replied, "You are young in soul, every one of you. For therein you possess not a single belief that is ancient and derived from old tradition, nor yet one science that is hoary with age. [22c] And this is the cause thereof: There have been and there will be many and divers destructions of mankind, of which the greatest are by fire and water, and lesser ones by countless other means. For in truth the story that is told in your country as well as ours, how once upon a time Phaethon, son of Helios, yoked his father's chariot, and, because he was unable to drive it along the course taken by his father, burnt up all that was upon the earth and himself perished by a thunderbolt,--that story, as it is told, has the fashion of a legend, but the truth of it lies in [22d] the occurrence of a shifting of the bodies in the heavens which move round the earth, and a destruction of the things on the earth by fierce fire, which recurs at long intervals. At such times all they that dwell on the mountains and in high and dry places suffer destruction more than those who dwell near to rivers or the sea; and in our case the Nile, our Saviour in other ways, saves us also at such times from this calamity by rising high. And when, on the other hand, the Gods purge the earth with a flood of waters, all the herdsmen and shepherds that are in the mountains are saved, [22e] but those in the cities of your land are swept into the sea by the streams; whereas In our country neither then nor at any other time does the water pour down over our fields from above, on the contrary it all tends naturally to well up from below. Hence it is, for these reasons, that what is here preserved is

reckoned to be most ancient; the truth being that in every place where there is no excessive heat or cold to prevent it there always exists some human stock, now more, now less in number. [23a] And if any event has occurred that is noble or great or in any way conspicuous, whether it be in your country or in ours or in some other place of which we know by report, all such events are recorded from of old and preserved here in our temples; whereas your people and the others are but newly equipped, every time, with letters and all such arts as civilized States require and when, after the usual interval of years, like a plague, the flood from heaven comes sweeping down afresh upon your people, [23b] it leaves none of you but the unlettered and uncultured, so that you become young as ever, with no knowledge of all that happened in old times in this land or in your own. Certainly the genealogies which you related just now, Solon, concerning the people of your country, are little better than children's tales; for, in the first place, you remember but one deluge, though many had occurred previously; ...

Meteor Defense Phaethon article Bronze age article The content and opinions expressed on this Web page do not necessarily reflect the views of nor are they endorsed by the University of Georgia or the University System of Georgia.

Meteoritica, Vol. XXIII (1963) PRELIMINARY RESULTS FROM THE 1961 COMBINED TUNGUSKA METEORITE EXPEDITION K P Florenskiy Report read at the Tenth Conference on Meteorites in May 1962 Translated by Spectrum Translation and Research, inc. Published by Taurus Press, inc., copyright 1965. INTRODUCTION Interest in study of unique natural phenomena is, in general, not confined to a single narrowly specialized viewpoint, and the 1908 fall of the Tunguska meteorite is no exception to this. The interests of various scientific disciplines converge on such investigations as at the focus of a mirror, and science itself is spurred to further development whose significance often ranges far beyond the framework of the original specific problem. In addition to questions pertaining to meteoritics, the fall of the Tunguska meteorite in particular gave impetus to the development of a number of concepts in such areas as the ballistics of supersonic velocities, the theory of large explosions, the structure of comets and features of their chemical composition, geochemical studies of cosmic dust, etc.; furthermore, it encouraged investigation of a variety of natural features in a remote and unexplored but promising area of Siberia. We have the meteorite to thank for the initial investigations of the swamps, soils and forests - studies that are important not only from the scientific standpoint, but also in practical terms. The conclusions derived from the study of this phenomenon bear on such problems, seemingly unrelated to meteoritics, as the wind resistance of trees in cold soils, improving timber harvests in northern areas, the history of swamp formation, reserves of peat in Central Siberia, etc. The results of this research represent not a random accumulation of data, but merge organically into the integrated whole that is the problem of the Tunguska meteorite. The history of studies made at the Tunguska meteorite site is divided into three basic stages which set the goals of the project and provided for collection of the necessary factual material without which theoretical consideration of the problem would have been unthinkable. The first stage, begun by L. A. Kulik, called for the collection of preliminary information, eyewitness accounts and data from observer stations in order to pin point the area of impact and to describe the physical phenomena that occurred outside the impact site. The second stage, also linked with the name of Kulik, involved a thorough study of a small area of ground in which a number of funnel-shaped depressions had been discovered; these had erroneously been identified as meteorite craters. The third stage was undertaken in 1938 with an aerial-photographic survey of a considerable area of the terrain, but essentially this stage did not develop fully until the author's 1958 expedition, which made an integrated study of the site and of all the possible consequences of the fall. The 1958 expedition [1] demonstrated the lack of justification for classifying the Tunguska fall as a crater-forming type and established that the center of the meteorite shock wave was located at some height above the ground; in addition, the expedition provided the first general map of the destruction that had been wrought, collected specimens of extraterrestrial dust from the area of the fall, drew attention to peculiarities of tree growth after the catastrophe and pointed to the possibility of using biological indicators; finally, the expedition pointed up the need for a careful study of the forest fire, etc. As a result of the work accomplished in this stage, the earlier theoretical concept of the fall was subjected to substantive review. A program for further study of the Tunguska fall was proposed, accepted by the Committee on Meteorites of the USSR Academy of Sciences, and subsequently approved at the Ninth Conference on Meteorites. The expedition set for1961 made provision for a further series of investigations to determine details of the meteorite's effects and called for an expanded search for fragments of meteoritic matter. The great popular interest in the Tunguska meteorite that arose after the 1958 expedition was to a considerable extent fostered by the fantastic suggestion of a nuclear origin for the explosion, an idea based on factual material of questionable competence. While I am aware of the advantages of sensational publicity in drawing public attention to a problem, it should be stressed that unhealthy interest aroused as a result of distorted facts and misinformation should never be used as a basis for the furtherance of scientific knowledge. A number of independent groups left for the area of the Tunguska meteorite fall in 1959 and 1960. Of these, the most serious was that of G.F. Plekhanov, whose work in 1960 was partly financed by the Siberian branch of the USSR Academy of Sciences, with support from the Committee on Meteorites. Basically, the project followed a plan that had been prepared in 1958; a substantial volume of factual material was accumulated. At the same time, it would not be out of place to point out that a number of projects carried out in 1959 and 1960 were based on fantastic ideas, and this resulted in unproductive expenditures related to the execution of the projects themselves, as well as in establishment of the fact that they had no relation whatever to the problem of the Tunguska meteorite. In this connection, we should make particular mention of A.V. Zolotov's group, which worked in this area in 1959 and 1960 and submitted hasty and unfounded conclusions on the basis of extremely inadequate and random data (see the resolution of the Ninth Conference on Meteorites. Meteoritika, Volume XX, 1961). Thus at the time when the 1961 expedition began its work, the situation was basically as follows: 1. On the basis of visual observation the general contour of the radially flattened forest area identified by Kulik was mapped out. Three zones can be distinguished within the limits of this area: random flattening (standing timber), mass flattening and partial flattening in a specific direction; the general plotting of these zones was confirmed in 1960. However, the boundaries of the zones (particularly to the northeast) and the direction of flattening call for additional refinement and quantitative characterization. There was no search for isolated islands of fallen trees outside the area of general destruction. Approximately 40

control plots, each 0.25 hectare in area, were laid out to obtain quantitative characteristics of the destruction [1, 2]. 2. There are no traces of a powerful ground meteorite explosion in the area; this is confirmed by a study of the south morass, where this fact was established through a number of helological studies, profiling of the bottom [3] and three magnetometric profiles [2]. The thermokarstic funnels [4] are not directly related to the explosion of the meteorite [l, 3, 5] and no magnetic anomalies were observed [2]. The possible stimulation of thermokarst development as a result of the fall [4] calls for additional helological research, as well as identification of the 1908 peat layer for purposes of a stratigraphic hunt for meteoritic matter. 3. The presence of live trees at the center of the catastrophe [1, 2, 4, 5] bears witness to the comparatively low level of any possible flash burning, whose general nature, along with the causes of the forest fire of 1908, requires additional study. 4. The large-scale map prepared from the results of the 1938 aerial survey of the center of the catastrophe by the MIIGAIK [Moscow Institute of Geodetic, Aerial Survey and Cartographic Engineers] on assignment from the Committee on Meteorites requires considerable revision based on field work. This map also confirms the existence of many stands of trees that survived in the central section of the affected area. 5. The soil study made in 1958 [1, 6] shows that the magnetite and silicate spheres first observed by L. A. Kulik and then by A. A. Yavnel' occur in small concentrations in the impact area. At the moment they represent the only possible fragments of the Tunguska meteorite and call for further study. Geochemical (metallometric) attempts to identify zones enriched with meteoritic matter [l, 2] produced no clear results and are of doubtful promise, unless the objects of the study are subjected to preliminary concentration . 6. The features of accelerated tree growth established in 1958 [1] have been confirmed by a great volume of data [7] and are peculiar to the central region of the impact area. In view of the fact that the causes of this phenomenon are not clear, work along this line should be continued in order to seek out biological indicators characterizing features of the 1908 fall. 7. On the basis of available data, it is at the present time held most likely that the meteorite "exploded" in the air. By way of explanation of this phenomenon a number of mechanisms have been proposed [8, 9, 10, 11, 12], but these cannot be regarded as reliable because of the inadequacy of working data. The most probable hypothesis is that which ascribes a cometary origin to the meteorite [13, 14], whose structure was friable [1, 8, 15, 16]. Available data are inadequate to form a clear picture of the phenomenon. Organization of the project. The expedition of 1961 was organized on the initiative of the Committee on Meteorites on the basis of a decision taken by the Ninth Conference on Meteorites and the 30 September 1960 Decree of the Presidium of the USSR Academy of Sciences [17]. In this connection, we should give special mention to Doctor of Geological and Mineralogical Sciences Ye.L. Krinov for his major organizational role as Scientific Secretary of the Committee on Meteorites and his monumental scientific contribution to the study of the Tunguska meteorite. The entire problem received the untiring attention of Academician V.G. Fesenkov, who directed the astronomical and physical investigations, and Academician A.P. Vinogradov, who was in charge of the work associated with the material composition of the meteorite. The nucleus of the expedition was made up of members of the Committee on Meteorites and the Vernadskiy Institute of Geochemistry and Analytic Chemistry; however, individuals from other organizations also participated (The Soil Institute, The Main Botanical Garden, Moscow State University, etc.). The Helology Section of the Forestry and Lumber Institute of the Siberian branch of the Academy of Sciences and the Forestry Assessment Section of the All-Union Forest Aerial Photographic Survey Association of the Main Administration of Forestry, USSR Ministry of Agriculture ("Lesproyekt") demonstrated interest by participating directly in the expedition. An outstanding feature of the expedition was the enlistment of a large contingent organized with the support of the Tomsk branch of the All-Union Geographic Society into the Combined Autonomous Expedition, designated KSE, of whose work we spoke earlier. This group joined the ranks of the 1961 expedition and worked under its authority. G. F. Plekhanov, the elected leader of this group and both a physician and an engineer, was put in charge of a section of the expedition; the numerical strength of the entire group considerably exceeded the original table for the expedition. In terms of qualifications and conscientious attitude, the Combined Tunguska Meteorite Expedition participants in the Combined Autonomous Expedition were capable of carrying out independent assignments unrelated to the responsibilities that they had assumed within the expedition. We should stress that proper and well-organized scientific leadership of such projects is of particularly great importance for the required concentration of research on major problems. The number of persons participating in the work of the meteorite expedition reached a total of 80, of whom some did not stay out the season. The program of the expedition called for extensive use of a helicopter to deploy individual groups and to transport heavy specimens. The actual unavailability of a helicopter, however, compelled the members of the expedition to move on foot; this significantly reduced both the total number and the size of the specimens collected. Some of the equipment and supplies even had to be dropped by airplane to the expedition base at Kulik's clearing. Part of the expedition departed from Moscow on 10 June, arrived at Vanavara on 16 June, and immediately began its work, gradually reaching full strength with the arrival of other colleagues. The expedition's works schedule was thrown off by the lack of the helicopter. There were no communications with Vanavara. The greater part of the expedition returned to Vanavara around the first of October, with the first snowfall. During the next few days the Chamba and other slowflowing rivers began to freeze. The logistic-support group of the expedition arrived in Moscow on 24 October, having successfully completed the evacuation of all expedition equipment (I.N. Yeliseyev, Ye.I. Malinkin).

I. STUDY OF THE EFFECTS OF THE METEORITE FALL FOREST FLATTENING

The flattening of the forest most accurately reflects the passage of the destructive wave accompanying the fall of the 1908 meteorite and can serve as a physical characteristic of the phenomenon.

Fig. 1. Dynamometric testing of tree resistance

A study of the devastated forest showed that the region of the forest flattened in 1908 was not one of homogeneous primeval intact taiga, but had had a complex history that must be taken into consideration in interpreting the data. Thus fire expert N.P. Kurbatskiy (The Forestry and Lumber Institute of the Siberian Branch of the Academy of Sciences) draws the following conclusion: " ...the region of meteorite impact in 1908 was basically a fire-devastated area that had been subjected to a treetop fire during the first half of the last century. A partly flattened dead and rotting forest was standing in this area. New forest growth had appeared among the dry and charred trees. By 1908, this second growth was some 70 to 100 years old. The southern and southeastern areas had apparently been subjected to fire somewhat earlier in the past than the central basin. The dead-forest was first flattened, and a fire then swept this territory. It is not out of the question that the set two occurrences took place at the same time... The fire did not destroy the trunks of living trees, but only scorched conifer needles and small twigs. The forest destroyed by the fire of 1908 was not flattened at that time but has in large part remained standing in the form of dead timber to the present time. The old stand of dead and badly rotted timber left by the fire of the last century could have been laid low during the fire itself and been scorched from the bottom as a result of a ground fire... There is nothing out of the ordinary in the suggestion that the larches were able to stand dead in the area of the meteorite fall for a period of 70 years after the fire of the previous century." On the basis of the forestry-assessment records, V.G. Berezhnoy (All-Union Lumbering Office of the USSR Ministry of Forestry - "Lesoproyekt") draws the following preliminary conclusions: "...it has been shown that at the time of the catastrophe the stand of trees in the area had, to some extent, been weakened by the fire at the end of the last century. For example, the great fire that produced the so-called 'western flattening' occurred in 1896. Larger diametral accretions are found in the area over which this fire had passed. The northern and eastern parts of this area (and quite possibly also the center) had been subjected to a fire during the 1880's... There are stretches of practically 'unburnable' forest within this area. These sections did not burn during the fire." At the same time, it is obvious that an estimate of the force of the shock wave that is based on the number of flattened trees must necessarily take into consideration the condition of the forest at that time. The wind resistance of a comparatively recent stand of dead timber is greatly increased as a result of reduced area catching the wind, particularly if the root system is still strong; later it diminishes to zero as the trees and their roots decay. Dynamometry studies of the flattening (wind resistance of the trees) in this area by means of a winch and a dynamometer (Fig. 1) (K.A. Lyubarskiy, I.T. Zotkin) yielded the following preliminary results (95 trees were studied): "There is no relationship between the felling moment and the species and age of the tree. There is a distinct relationship between the moment and the tree diameter, analytically nicely described by a parabola (Fig.2). These parabolas are completely identical for fine (melkozem) and rocky soils. For moist riverside soil the parabola takes a noticeably flatter course (the felling moments are significantly smaller). The relative scatter diminishes in inverse proportion to the diameter of the tree. It is not related to the azimuth of the felling or to the direction of the slope (upward, downward, to the side). From the standpoint of force there is no difference between snapping and uprooting, i.e., both cases array themselves along the same parabola. The parabolic relationship is retained for dead-timber logs, but the parabola in this case is extremely flat, the felling moments are minimal, and the scattering is therefore very wide" (the dead-timber data pertain to timber killed in 1908, Table 1). TABLE 1 Average Felling Moments for Trees in the Area of the Tunguska Catastrophe (Pines, Larches) (Preliminary Data) Tree diameter, cm Area no.

Nature of area 15

20

25 Felling moment, ton-m

30

1 and 2

Dry soil

1.1

2.3

3.7

5.5

3

Marshy soil

0.7

1.5

2.8

4.2

4

Brush dead 53 years

0.4

0.8

1.3

1.9

Unfortunately, we were unable to study the relationship between log strength and age - a matter of unquestionable interest - because of the difficulties which we encountered in determining the time at which this stand of timber was killed off.

Fig. 2. Felling moment as a function of tree diameter. 1) Trees in fine and rocky soil; 2) dead-timber stand of 1908.

That there is no relationship between the strength of a tree and its species would seem at first glance to be a rather bold conclusion: a definite distinction is made in forestry between "wind-susceptible" and "wind-resistant" species. Apparently this classification is not applicable to regions of cold and frozen soils, where deep root systems ("tap roots") cannot develop and where the roots of virtually all species develop in similar fashion, along the surface of the ground ("shield" or lateral root system), in virtual independence of the nature of the soil, i.e., the slow thawing of the soils in the summer limits the depth of root penetration. The soil and soil-temperature variation studies conducted in the area by soil scientist A.A. Yerokhina (Dokuchayev Soil Institute of the USSR Academy of Sciences) demonstrated that there is virtually no permafrost to a depth of 1.5 to 2 meters in the dry forest soils of this area, but that the seasonal frost thaws out only toward the beginning of August. The moist and marshy soils have permafrost base layers. The general characteristics of the felling were studied in a number of ways.

Fig. 3. Distribution of flattened trees by direction in various sample areas. A histogram of this type, including about 100 trees, corresponds to each of the arrows in Fig. 4.

To provide an over-all description of the flattening effect, we used a graphic method (V.G. Fast and D.V. Demin) which involved taking the azimuths of all of the fallen trunks in a sampling area containing some100 flattened trees (generally 0.25 hectare) and plotting their variation diagram (Fig. 3) with indication of the trunk thicknesses. The numbers of dead-timber and old living trees were also noted. As a result of the work carried out in 1960 (Plekhanov et al.) and 1961, approximately 200 such areas were investigated to obtain a reliable profile of the entire area of flattened forest. Both the mean direction of the flattening, which reflects the direction of the wave front, as well as the directional dispersion of the flattened trees, which is a function of shock-wave force, can be used to describe the motion of the wave. The evaluation yielded a somewhat exaggerated value, since areas with the most clearly defined flattening were selected as controls and, moreover, it was impossible to take into consideration the relationship between the trees that had been felled live and those that were dead. The total area of flattened forest covers approximately 2000 square kilometers and generally coincides with the boundaries established by the1958 expedition. However, it has now been established that the flattening extended farther to the northeast, along the Sil'gami Range to the summer trail leading to Strelka, a fact which had also been noted in 1960. Thus the general contour of the felled forest takes the form of a triangle, apex forward, symmetrical about the meteorite trajectory determined by Krinov. It is characteristic that compilation of a large volume of data shows no significant deviations from the radial in the directions of the fallen trees. The arrows obtained by this method are more or less uniformly distributed over the entire felled area (Fig. 4).

Fig. 4. Flattening of timber on the basis of 1961 data. 1) Sampling areas encompassing 100 trees; 2) directions based on several trees; 3) 1960 routes; 4) stretches with limited or poorly defined flattening; 5) stretches in which there was no flattening at all; 6) positions of the forestry-assessment plots; 7) huts; 8) boundaries of the 1908 fire where its natural propagation is seen distinctly; 9) general boundary of flattening; 10) southeastward variant of the meteorite trajectory, after Krinov.

Figs. 5. Present appearance of felled timber.

For purposes of evaluating the information from the control areas and in order to establish a detailed picture of the forest destruction, special forestry-assessment plots were surveyed and both the living and dead tree son these areas described (Fig. 5). Over a number of years, beginning with 1958, the methods employed for this part of the operation were gradually improved and in 1961, in its final form, the work came under the direction of V.I. Nekrasov (Main Botanical Garden of the USSR Academy of Sciences), V.G. Berezhnoy and G.I. Drapkina (All-Union Forest Aerial Photographic Survey Association of the Main Administration of Forestry of the USSR Ministry of Agriculture). Some of the forestry-assessment plots were staked out and partly described in 1960 (V.I. Nekrasov, Kolesnikov); they were distributed in the form of a cross passing through the epicenter of the destruction to the boundaries of the flattened forest (55 plots), with an additional 40 plots located in the intervening quadrants. The relationship between the percentage of fallen trees and their directional distribution can be established on the basis of the control areas, which can also be used to describe the general condition of the forest in 1908 and at the present time. A special investigation was undertaken (Zotkinetal.) to detail the felling in the center of the area covered by the chart prepared by the Moscow Institute of Geodetic, Aerial Survey, and Cartographic Engineers. This study involved the plotting of arrows indicating the direction of the fallen trees at points not examined by aerial photography, and surveys of special control areas to ascertain the effect of local relief on the action of destructive wave. This results in rather convincing evidence that there is a pronounced increase in directional flattening on reverse slopes (with respect to the epicenter) near the epicenter-an indication of an "explosion" at altitude. As we have noted, the "zone of indifference," also known as the "chaotic flattening" or "telegraph pole" zone, occupies an area somewhat smaller than that indicated by the 1958 chart. This may indicate a somewhat lower center of wave origin than had earlier been supposed (Fig. 6). Thus the collected material on the flattening of the timber permits us to draw the following conclusions: 1. The total area of flattened forest is in rather good agreement with the map prepared in 1958. An exception is the extension of the flattened area to the northeast, as can be seen from the map showing the propagation of new forest. 2. The collected material is quite complete and there would be little gained from further field refinements prior to complete evaluation of the data obtained. 3. Nowhere in the directional studies of the fallen trees were any significant deviations from radial flattening noted. 4. By 1908 the forest consisted to a considerable degree of standing dead timber, and computation of both the over-all force of the shock wave and its isobars must be accomplished with consideration of this factor. Areas of forest that had not burned by 1908 survived to a significant extent and were not flattened. 5. The influence of local relief on timber flattening in the vicinity of the epicenter is of a nature such as to confirm that the explosion took place at some height. 6. The slightly smaller central zone of random dead-stand flattening as compared with the 1958 data speaks against an excessively high explosion center. 7. The data collected must be subjected to careful evaluation.

THE FOREST FIRE OF 1908 AND FLASH BURNING OF THE TREES As had been pointed out in 1958, a forest fire originated at the point of meteorite impact and spread in the usual manner. Thus the boundaries of the fire do not coincide with the boundaries of a possible flash fire, as Zolotov sought to prove (1959). [* A report on the work of A.V. Zolotov during his 1959 expedition.] While no one has dismissed the possibility of a flash fire, it has not been definitely established either. The 1961 investigations of the injuries inflicted on live trees in the vicinity of the epicenter (Zenkin et al.) revealed a large number of still surviving trees and the fact that the injuries to these trees were oriented in nature.

Fig. 6. Schematic map show in a distribution of flattening, dead timber and live trees at the epicenter. 1) Flattened trees; 2) dead timber; 3) surviving trees; 4) expedition shelters.

N.P. Kurbatskiy, a member of the 1961 expedition, describes the features of the fire in this area as follows: "...distinct signs of the spreading of the 1908 treetop fire were found in the form of arcuate strips and surviving older forest to the north of the Kimchu River, at a distance of 1 to 2 km from the bank, in the stretch from Lake Cheko to the extensive marshes on the left side of the river. In this area the fire spread from south to north. Indications of the fire's spread were found on heights to the north of Lake Cheko, as well as on the western slopes of hills 373.6, 491.0 and 476.0. From here the boundary of the fire area can be traced easily along an arc from the mouth of the Chavidokon River to Mount Shakharma. The surviving traces of the fire-line advance indicate that it spread toward the west and southwest, i.e., as if from a central depression. The treetop fire here gradually changed into a ground fire, with some damage to the old forest. On the northeastern slopes of the heights where the headwaters of the Churgim River rise there are arcuate strips of old forest, convex toward the south. We find identical signs of the spreading fire on Mount Shakharma, but facing east... The old forest remained intact only in narrow strips along the banks of rivers with highly developed valleys and in the form of solitary trees in the midst of swamps and rock streams." "The rounded shape of the fire site and the complete destruction by fire of the old forest over an extremely great area are outstanding features of the area; it differs in these respects from ordinary forest burnouts after the passage of treetop fires in the presence of a strong wind... Of the surviving areas of primeval taiga, we inspected only two, 2 to 5 hectares in area, situated on the flat saddle slopes of the northwestern heights surrounding the central depression... During the course of this inspection on 28 June 1961, the sixth day after a heavy rainfall, the ground vegetation in these areas was extremely wet and would not burn, although flammable material on the ground ignited easily throughout the rest of the impact area. It is obvious that these areas differ from the remaining territory in having an elevated resistance to fire. In the past (apparently, in 1908) a ground fire penetrated these sections from the fringe growth of that time, but did not spread through them." "The 1908 fire flared up at several points: in the central basin, on the territory adjacent to the Khushmo River between the Churgim and Ukagitrivers, as well as on the northeastern slopes of the Khladnyy Range. The fire was preceded by a dry spell, which was responsible for the widespread and uniform burning of the forest and the spreading of the fire to the marshes. Such a set of circumstances is possible for this area in the month of June, but not altogether usual. The 1908 fire spread rapidly through the treetops of the meteorite area, before a wind moving at a speed of 6 to 10 m/sec. At this velocity, the wind was a local phenomenon and a result of powerful rising currents of combustion products and heated air. The fire lasted for at least five days. During this time the direction and velocity of the wind varied with the diurnal variations in temperature and with changes in the intensity of the fire front as it enveloped various elements of the terrain relief. The fire died out during the first ten days of the month of July in 1908 as a result of unfavorable weather conditions. The trunks of live trees did not burn during the fire; only needles and small twigs were scorched." As we are well aware, forest fires generally start on ignition of floor litter, which is the most highly combustible material. To determine the fire hazard in this area and the quantity of heat required to start a fire, a series of experiments were carried out to ascertain the moisture content of the various types of ground litter as a function of the length of a dry spell (N.P. Kurbatskiy, T.M. Sleta). Evaluation of these data by the Forest Fire Prevention Laboratory at the Forestry and Lumber Institute of the Siberian Branch of the Academy of Sciences should make it possible to establish a numerical scale for the minimum quantity of radiant energy required to start the 1908 fire. The maximum quantity of energy can be found on the basis of the fact that various species of trees (larches, pines, and cedars) survived in the area of the epicenter, in some cases even retaining live branches.

Fig. 7. Physiological scorching of larch twig near epicenter by light. The oriented cambium injury of 1908 can be seen; the twig at that time was no more than 8 mm thick. The injury was subsequently completely invested.

Studies of live branches (older than 53 years) on trees growing in open areas were undertaken to seek out evidence of a flash fire, to evaluate its intensity and direction (G.M. Zenkin, A.G. Il'in, L.F. Shikalov et al.); in part, this is a continuation of work started in 1960 (Plekhanov et al.). It was established in these investigations that branches (primarily of larches) which in 1908 did not exceed 8 to 15 mm in thickness often show traces of injuries that date from 1908, and have subsequently been invested by bark (Fig. 7). The damage is noticeable on the upper portions of the branches, thus making it impossible to associate these injuries with ordinary fires. Moreover, they are oriented toward the supposed center of the meteorite explosion. The severity of these injuries diminishes significantly with increasing distance from the epicenter. The damage indicates a fungus disease that affected the injured parts of the cambium. We thus have a serious basis for assuming that these injuries are a result of physiological scorching of cambium cells during the fall of the meteorite. Statistical reduction of the collected material will assist us in establishing the factors responsible for the appearance of these injuries, and, if they are associated with a flashfire, will be helpful in determining its intensity and direction. The latter is of interest from the standpoint of determining the spatial position of the meteorite at the instant of maximum brightness. [* G.M. Zenkin places the emission center at 1.5 km to the southeast of the epicenter of destruction, at a height of about 5 km.] TABLE 2 Injury Distribution (Flash Fire?) at Various Distances from Epicenter* Distance from epicenter, km Direction 3

4

5

6

7

8

9

North ……………….

-

+ (2)

-

-

-

-

- (3)

East ……………….

-

+ (2)

-

+ (2)

-

- (1)

-

South ……………….

+ (1)

+ (1)

+ (2)

-

+ (1)

-

-

West ……………….

+ (1)

-

-

+ (1)

-

-

- (1)

The + sign indicates injury observed; the - sign indicates no injury observed; (3) represents the number of trees inspected.

The distribution of the above injuries as a function of distance from the epicenter, after the data of Zenkin and Il'in, is presented in Table 2. Shikalov and Ivanova submit data indicating that analogous instances of injury were observed in less pronounced form at distances up to 9 km to the north and west of the epicenter, and as far as 10 km to the south. Extremely rough and approximate calculations of the energy required to produce physiological scorching and local mortification of the cambium on a branch approximately 1 cm thick yield a value of 5 to 15 calories per square centimeter. The illumination value cannot be significantly higher (more than double this figure), since this would lead to marked charring of the bark, and no such phenomenon was observed. Approximately the same energy is required to ignite dry forest debris, and this could lead to a forest fire. According to a preliminary evaluation, this result for the energy of the light pulse (at a distance of up to 9 km from the epicenter) is smaller by approximately

half an order than the result obtained by Zolotov. For purposes of comparison we cite certain data (Table 3) on flash burns suffered in atomic explosions (see "The Effects of Nuclear Weapons," [Deystviya yadernogo oruzhiya], translated from the English, Voyengiz,1960) TABLE 3 Luminous Irradiation Resulting in Injury, for Two Explosion Forces

Effect

Energy of irradiation by light, cal/cm2 for TNT equivalent of 20 kilotons

10 megatons

Burns, human skin:

-

-

First degree

2

3.5

Second degree

5

7

Third degree

7

11

Charring of fir, pine and maple bark

10

15

Kindling:

-

-

Dry rotten wood

4

9

Fine grasses

5

10

Fallen leaves

6

12

White-pine needles

6

14

STUDY OF THE EFFECT OF THE METEORITE ON THE SWAMPS The observations of the 1958 expedition indicated that there was no meteor crater in the south morass and that there was no relationship between the formation of the thermokarstic funnels and the fall of the meteorite; however, these observations were not sufficiently reliable. Yu.A. L'vov, Kovalevskiy et al. undertook a rather detailed inspection of the swamps in 1960. They established that "all of the structural features of the basin's marshes are readily explained by terrestrial factors. No interbedding of peat and soil in the south morass was observed, Kulik's data not withstanding... The fall (B.I. Vronskiy) of small meteoritic fragments cannot be used to explain the thermokarsts...a four-to-six-centimeter peat layer in which the 1908 stratum was deposited is easily identified... Even in the event of negative results, the search for meteoritic matter in the peat must be repeated" (taken from a letter by L'vov to Florenskiy, dated 28 December 1960). The section of the helology team from the Forestry and Lumber Institute of the Siberian Branch of the Academy of Sciences, headed by Doctor of Biological Sciences N.I. P'yavchenko, worked from 22 June through 6 July 1961, while the main unit of the helological section headed by S.P. Yefremov remained on the job to study the surrounding marshes throughout the entire summer.

Fig. 8. A view of the south morass.

I cannot dwell here on a discussion of the extensive work program undertaken by this unit, even though it is of considerable interest to the helologist. N.I. P'yavchenko formulates his replies to questions concerning study of the Tunguska fall in the following manner. "Differentiation of the south and north morass surfaces into hillocks and 'mochazhina' [land permanently wet from outflow of underground water] is a result of thermokarstic processes and, possibly, a result of phenomena related to ancient water erosion... The formation of funnels in the swamps is not associated with the fall of the meteorite or fragments of it. No embankments of ejected peat have been built up around the funnels, the peat layer is not intermixed with the soil and it is of rather along the line of contact with the peat hillocks are steep and frozen... Numerous core samples of the peat deposit uniform depth throughout the entire area of the funnel, the mineral base is flat, and the walls in the south and north morasses fail to reveal any mixing of the peat with the 'ooze' or subsoil. The peat deposit exhibited rather clearly oriented stratification throughout... The 'embankments' on the surface of the south morass, which extend, with slight separation from one another, in the direction perpendicular to the runoff, are ordinary ridges 20 to 30 centimeters in height covered with dwarf arctic birch, bog underbrush, hypnum and sphagnum, and quite often with woody vegetation (Fig. 8). These ridges are formed in wet marshes because of surface cracking due to frost and raising of the peat around the edges of the cracks, which improves the drainage of the area adjacent to the crack, thus favoring the growth of vegetation requiring less moisture... Traces of fire stand out clearly in the peat deposits of the hummock areas in the north and south morasses. In the majority of cases two fire levels stand out clearly: an upper level approximately 20 and in spots 30 years old; a lower level, about 50 years old... The lower level is quite thick, ranging from 3 to 5 cm, and occasionally more. This level contains much charcoal, ashes and plant residue... All of the old trees that survived on the peat hillocks show searing only on the lower parts of their trunks, which indicates that the fire moved along the ground; this is natural in view of the high degree of thinning of woody growth in peat bogs... No regular intensification in the growth of trees, dwarf arctic birches, bog underbrush, and mosses in the marshes after 1908 was observed. Among the old larches, the increment during the past 2 to 3 decades has been insignificant. Young larches and pines appearing on the peat hummocks after 1908 are characterized by growth satisfactory for frozen peat bogs and rather uniform height and diameter increments. In addition, severely stunted trees are encountered. These differences are associated with the ecological conditions of vegetation growth... The increment in sphagnum in the permanently wet ground and thermokarsts amounts to 2.4-2.5 cm annually, which is quite normal for this zone. Under extremely dry conditions Sphagnum fuscum increases at a rate of about 1 cm per year on the peat hummocks." There were no clearly defined changes in the hydrological regime of the marshes that were associated with the events of 1908. The gradual aggrandizement of the morass at its boundaries and the partial submergence of dead growth is typical of many of the marshy areas of this region, bearing absolutely no relation to the fall of the meteorite. The age of the south morass runs to many thousands of years, and determination of the absolute age at which swamp formation began is a matter of considerable interest, since it represents information totally unknown with respect to the marshes of Central Siberia. This determination can be accomplished by using the radiocarbon method on specimens of wood raised from the very bottom of the south morass. Thus as a result of detailed helological investigations in 1960 and 1961 we may regard as quite reliable the conclusion that there is no relationship between the fall of the meteorite in 1908 and the manner in which the south and north morasses were formed. THE BIOLOGICAL EFFECT OF THE FALL The 1958 expedition drew attention to the pronounced change in the rate of growth of a number of trees subsequent to 1908, and pointed up the possibility of using "biological indicators to ascertain features dating from 1908, as well as general changes in conditions brought about by the fall of the meteorite." Yemel'yanov and Nekrasov showed in their subsequent work that accelerated growth is characteristic of a wide region around the center of the meteorite fall. A number of biological indicators suggested the probability that this phenomenon was in some manner associated with meteoritic matter and should be studied. In 1960, together with a number of other colleagues, they began laying out the forestry-assessment plots which made it possible to bring to light the unusual nature of this phenomenon. A group of biologists joined the 1961 expedition of the Committee on Meteorites to establish the boundaries and causes of the accelerated growth of forest in this area. Because the problem of accelerated forest growth and increased timber harvests in the areas of the north is of prime practical importance, the AllUnion Forest Aerial Photographic Survey Association of the Main Administration of Forestry of the USSR Ministry of Agriculture participated in the project by dispatching a forestry-assessment section to work together with the expedition. This work was performed by Candidate of Biological Sciences Nekrasov, a forestry specialist; by Berezhnoy, Drapkina, and a number of others. A number of important details incidental to this work were brought to light in connection with the nature of the meteorite-connected injuries sustained by the forest. As a result of the work carried out in 1960 and 1961, a total of 95 forestry-assessment areas were laid out, and all of the biological aspects of the phenomenon were studied here. The change in the rate of forest growth can be associated either with a change from the normal ecological conditions of growth due to the tremendous forest fire

and flattening of the forest which took place in 1908, or with the action of stimulants that appeared in the soil on disintegration of an extraterrestrial body of unknown composition. Although literature sources indicate that the aftereffects of ordinary forest fires and forest uprooting with which we are familiar from European silviculture should not last longer than 15 to 20 years, they persist, occasionally without noticeable abatement, for a period of 40 to 50 years, in the area of the meteorite fall. Nekrasov has expressed doubt as to the possibility of explaining this phenomenon in terms of purely ecological factors (more sunlight as a result of thinning, the effect of ash fertilizers, a change in the heat and moisture regime of the soil, soil aeration, etc.). The study of the soil heat regime which was conducted by Soil Scientist A.A. Yerokhina to shed light on the influence exerted by frost phenomena demonstrated that there was no evidence of permafrost in the dry forest soils to a depth of at least 1.5 to 2.0 meters, and that it is difficult to detect any change in the thermal regime of the soils with the methods available to the soil scientist. To supplement the silvicultural work, the growth rates of oats in the soils of various sections of the region were determined (A.B. Osharov, a plant physiologistat Tomsk State University); soil microflora were identified (N. V. Vasil'yev, a microbiologist from the Tomsk Medical Institute), and a study of the root systems of trees and their changes subsequent to 1908 was carried out (Osharov). The possibility of detecting a change in the thermal regime of the soil and the related possible deeper penetration of the root systems after 1908 prompted this last project. Particular attention was devoted to the growth pattern of bog vegetation communities during the helological studies. The office evaluation of the secured data, which should supply the answers to these questions, has not been completed, and thus the expedition has not as yet formed any final conclusion regarding the results of the project. However, we can make the following preliminary comments. 1. Where we have a similar combination of fire and forest flattening due to ordinary causes outside the environs of the epicenter of meteorite impact ("the western flattening" of 1896, the fire in the vicinity of the Chamba in 1937), an equally persistent acceleration of forest growth is encountered. 2. There is no indication whatever of any change in the growth rate of bog communities beyond the moss layer which grew directly on the mineral-rich 1908 layer over which the fire had passed. 3. Although acceleration of forest growth after 1908 was observed in areas bearing no traces of the fire or flattening of the forest, these areas are situated in the immediate vicinity of extensively destroyed areas and are spatially limited, and thus subject to the over-all regime of a much wider region. 4. No clear differences corresponding to boundaries of accelerated forest growth were ascertained as a result of cultivation of oats in various soil areas of the region in which the meteorite fell. 5. The boundaries of accelerated forest growth follow the boundaries of the fire and flattening of the forest quite closely, but they do not correspond to the distribution of meteoritic matter as obtained by other methods. All of the above compels us to express grave doubt as to the possible participation of meteoritic matter (in one form or another) in the stimulation of tree growth in this region, and suggests that the prolonged aftereffects are associated with features of the ecological conditions of forest growth in this zone of Central Siberia. Forestry experts Berezhnoy and Drapkina (All-Union Forest Aerial Photographic Survey Association of the Main Administration of Forestry of the USSR Ministry of Agriculture) came to the same conclusion. This has no bearing on the possible practical application of the features studied to the promotion of silviculture in the northern regions of Siberia.

II THE SEARCH FOR METEORITIC MATTER Various dispersion states must have been present during the flight and disintegration of the Tunguska meteoric body in the atmosphere, differing in the nature of their scattering over the surface of the earth in accordance with time of formation and degree of dispersion. At the very least, we may assume the presence of the following forms to have been probable. 1. The dust-and-gas tail of a comet, torn away in the uppermost layers of the atmosphere and dispersing over the entire surface of the earth to produce bright nights. 2. The dissipation of ionized gas in the atmosphere along the flight path of the meteorite, without any settling of meteoritic matter. 3. Liquid and vapor condensation products swept from the heated substance of the meteorite to form its train. Coarse fractions of the train may have reached the surface of the earth in the form of molten droplets that froze into meteoritic spheres, settling along a more or less clearly defined strip, the finer droplets scattering uniformly or settling out over a great distance. 4. The "explosion" products of the meteorite. Their state depends primarily on the composition of the meteoroid. Volatile cometary components dissipate without leaving a trace; the remaining components form local conglomerations depending on the nature of the explosion and the degree of dispersion. Individual large meteoritic fragments may reach the surface of the earth along the line of the meteorite's flight path, beneath its train, or at a point beyond the epicenter of the "explosion." There cannot be many such fragments, and in the absence of precise data on the trajectory of the meteorite the discovery of such fragments 50 years after the fall is a matter of pure chance. Fine meteoritic dust in solid form is scattered and it is difficult to distinguish it from ground formations unless it is composed of pure unoxidized iron. The atomized fused meteoritic material should have frozen into spheroidal particles that could be carried for great distances by the wind to form local accumulations. The gaseous products and their derivatives do not form distinct local accretions and any search for these would be virtually hopeless. The deposits of these various product types need not in principle coincide with one another. Of all of the enumerated forms of meteoritic matter, the 1958 expedition (Florenskiy et al.) identified only magnetite and silicate spheres, and these in negligible

concentrations. Additional specimens were collected by B.I. Vronskiy in 1959 and 1960. All attempts (magnetometry, metallometry, radiometry) to ascertain the presence of cosmic matter in some other form (1958, 1959, 1960) remained entirely without result. At the same time, however, the limited concentration of such particles precluded definite classification as fragments of the Tunguska meteorite, since they are indistinguishable from the ubiquitous meteoric dust. The question of meteoric (cosmic) dust is important and repeatedly raised in the literature. However, it had not been the subject of an adequately serious study until recently, and quantitative estimates of meteoric dust varied over a very wide range: the estimates of various authors sometimes differed by many orders of magnitude. The properties of this dust are generally studied by astronomical methods, with only the magnetic component being determined from ground deposits. Thus the problem of studying the material composition of the Tunguska meteorite is inseparably interwoven with the general study of meteoric dust, and part and parcel thereof.

Fig. 9. A concentration installation at the Khushmo River.

Attempts to isolate material from the Tunguska meteorite were carried out in the following manner. 1. Isolation of dust from the surfaces of tall stumps ("telegraph poles") snapped by the 1908 explosion (Yu M. Yemel'yanov). The method called for removal of the trunk surface, grinding it up, and boiling it to a pulp in water. Large wood particles were removed from the resulting mass by filtration, and the minute fractions were collected. This concentrate was dried for subsequent separation in gravity solution. The extremely laborious operation of collecting enough dust that had settled in the cracks of the trunk surfaces failed to produce any large number of specimens of adequate size. The upshot was a single specimen, collected from a surface of approximately one square meter in the vicinity of the Churgim falls, 3 km to the south of the "explosion" epicenter. Preliminary study of some of the material showed a clear preponderance of terrestrial quartz dust in the presence of minute particles possibly associated with wood residues. The specimen is of interest since it provides a characteristic of the average dust fall in this region over a period of 53 years, including possible residues of the Tunguska meteorite and other meteor particles. 2. Identification of strata in peat-bog and lake deposits. The identification of the1908 peat layer was accomplished in two ways: a) in the north morass and in the vicinity of Khoy Brook, about 20 square meters of a scorched layer containing a large quantity of ash associated with the 1908 fire was identified; the ash, together with the peat residue, was concentrated by the customary method for soil samples; b) successive layers of peat from the west morass in the bend of the Khushmo River (which had not burned) were identified and set afire for subsequent analysis of ash composition. Silt specimens from Lake Chekoand the lake in the bend of the River in the west morass were collected for subsequent stratigraphic study (P.N. Paley et al.) with a grab dredge and a swamp drill designed by N.I. P'yavchenko. The various samplings from the bottom of Lake Cheko (P'yavchenko, Kozlovskaya) revealed extensive development of silt up to 7 meters deep, indicating an ancient origin for the lake (tentatively estimated at 5000 to 10,000 years), thus completely contradicting the hypothesis of the formation of the lake as a result of the Tunguska meteorite fall (V. Koshelev, 1960). 3. The search for meteoritic matter in the soils. The observations made by Soil Scientist Yerokhina confirmed the validity of the soil sampling method which we used in 1958; it was possible with this method to remove a layer 2 to 3 cm thick, including the lower section of the litter and the upper layer (1.5 cm) of the subsoil. With this sampling method, the weight taken from an area of one square meter usually ranges up to 10 kg.

Fig. 10. Spheres of cosmic origin found in the area of the Tunguska meteorite fall.

The average weight of a sampling collected by the two-man teams on foot amounted approximately to 20 kg from a sampling area of two square meters. Wherever possible, the samples were taken from unflooded dry level areas without heavy vegetation cover. The collected specimens were sent to the concentration section (Kozlov, Vronskiy, Malinkin, Gorbunova), where the concentration was accomplished on a vibration table (Fig. 9) and the heavy fraction consisting of particles smaller than 0.25 mm was separated; the specimens were subsequently subjected to magnetic separation and then they underwent preliminary inspection through a binocular magnifier (N.I. Zaslavskaya, G.M. Ivanova, N.P Rodionova). The silicate portion was not studied in the field, and the concentrated specimens were brought back to Moscow for further evaluation. We worked on the assumption that the earlier samples (1958), which had been more crudely concentrated, contained both magnetic (magnetite) and silicate spheres (Fig. 10).With the old concentration method, in which a significant portion of the silicate spheres were lost, these spheres were found to be present in proportions of 3:1. It is not out of the question that the samples include polyhedral particles of cosmic origin; however, a method has yet to be developed for their identification. Under field conditions it is precisely the magnetic spheres that most readily lend themselves to concentration and identification. If we assume that the number of these spheres bears some relation to the total number of cosmic particles, they represent the most convenient indices to the presence of meteoritic matter. Based on these spherical particles, preliminary field analysis of their composition becomes possible, as does a purposive search for the scattering ellipse of the meteorite on the basis of even a slight increase in the concentration of meteoritic matter. All of the previous samples that were collected in the vicinity of the epicenter (as well as the 1961 samples) exhibited an altogether negligible concentration of spheres. Since the average number of such particles had not been established for the soils, they can easily be attributed to the back ground concentration of meteoritic dust of this type. At the same time, the general pattern of the physical process involved in the scattering of these particles appears completely clear to us. We have already mentioned the dissipation of the meteorite train. In addition, the scattering of the meteoritic matter is governed by the explosive disintegration of the meteorite, accompanied by the liberation of a large quantity of thermal energy. This inevitably led to the formation of a powerful ascending current of hot air the analog of the radioactive cloud that rises from a nuclear explosion. Unlike the nuclear explosion of the pure air-burst type, which is virtually free of any dust particles ,the cloud resulting from the Tunguska explosion may have contained a significant quantity of dust and liquid particles, although it was on a considerably lower energy level. From this standpoint, it would more nearly resemble the cloud which results from an atomic explosion at or very near the ground, which draws up a substantial quantity of dust particles. Without insisting on absolute consistency between the explosions, which involve markedly different levels of energy, we are nevertheless obliged to seek an analogy to the Tunguska fall in nuclear explosions, since they most nearly approximate the fall in terms of force. The base of the mushroom cap of an atomic cloud rises to a height of 8 to 16 km, while the height to which the top of the cloud rises is a function of the force of the explosion and ranges between 20 and 40 km. The cloud produced by the eruption of Mount Bezymyannyy on Kamchatka in 1956 reached a height of 36 km. The dust particles picked up by the thermal currents settle out at a comparatively slow rate and may be scattered far and wide by the wind. Following Stokes' law, the fall velocity of particles ranging in size from 5 to 300 microns is given as v = 0.11d2p m/hr in air, where p is the particle density in grams per cubic centimeter and d is the particle diameter in microns.

Fig. 11. Map showing the distribution of phenomena accompanying the Tunguska meteorite fall. The circles are drawn at 20-km intervals. 1) Approximate boundary of area with trees subject to physiological light scorching- 2) boundaries of felled-timber area and directions of fall- 3) sites of samplings rich (x > 8) in magnetite spheres. The areas of the small circles are proportional to the concentrations of particles; 4) samplings with few magnetite spheres; 5) hypothetical scattering ellipse of the meteorite.

Quartz particles descend from a height of 24,000 meters at the following fall velocities: Particle diameter, microns . .250 150 75 33 Fall time, hours . . . . . . .1.4 3.9 16 80

Thus, on the basis of particles 150 microns in diameter, which correspond to the largest sizes found earlier, and assuming that these particles had risen to a height of 12km, the time for their descent would be 2 hours. TABLE 4 Mean Concentration of Magnetite Spheres as a Function of Distance from the Center of the Explosion of the Tunguska Meteorite (Preliminary Data, with the Concentration Given for an Arbitrary Unit of Area)

Average content Distance from epicenter, km

Number of particles

Average of samples

0-10

1.5

6

20-30

4

16

40

8

11

60-80

21

6

TABLE 5 Mean Concentration of Magnetite Spheres for the Southern and Northern Halves of the Investigated Area as a Function of Distance from the Epicenter Southern part Distance from epicenter, km

Northern part

Number of particles

Average of samples

Number of particles

Average of samples

20-30

5

8

2.5

8

40

3

6

15

5

60-80

10

2

26

4

Following accepted practice, assuming the average wind velocity to be 24 km/hr, we find that particles will be carried 50 km from the center of the explosion before settling to earth. TABLE 6 Mean Concentration of Magnetite Spheres of Cosmic Origin as a Function of Distance from the Epicenter for Averaging over Quadrants (Preliminary Data Concentrations given for an Arbitrary Unit of Area) Northwest Distance from epicenter, km

Southeast

Northeast

Southwest

Number of particles

Average of samples

Number of particles

Average of samples

Number of particles

Average of samples

Number of particles

Average of samples

20-30

1

4

7

5

4

4

2

3

40

14

3

3

4

17

2

3

2

60-80

33

3

10

2

5

1

_

_

Fig. 12. Concentration of magnetite spheres in the soil as a function of distance from the epicenter: a) Averaging over quadrants from the southeast to the northwest; b) averaging over quadrants from the southwest to the northeast; c) averaging over all samplings, without consideration of direction.

In response to an inquiry from the Committee on Meteorites, the Central Weather Forecasting Institute provided the following description of the day on which the Tunguska meteorite fell (from a letter dated 11 May 1961, Ref. No. K-573): "On the basis of data available to the Institute, on 30 June 1908 the site of the meteorite fall was under the influence of a zero-gradient pressure field, with weak southeasterly winds at 2 to 5 meters per second."

Fig. 13. Recurrence of samples with a specific number of magnetite spheres.

The synoptic situation provides a basis for the contention that there were no strong air currents at heights of 3 to 4 km. The air currents were moving from the southeast and south to the northwest and north. The velocity of the wind ranged approximately between 30 and 40 km/hr. The direction of the air currents remained constant from the site of the meteorite fall to 65-70ø North Latitude. The air currents then deflected eastward, becoming almost westerly, assuming a northwesterly direction over the basin of the Lena River and the Far East." In view of the rather indeterminate nature of the hypothetical initial data (and in view of completely contradictory data based on a synoptic analysis of the same situation, as obtained through G.F. Plekhanov from Tomsk) it was decided to break the sampling network up into circles with a distance of 20 km separating them and with the sampling areas in checkerboard array (Fig. 11). Had there been a helicopter at our disposal, we would have been able to complete the entire program of work and to obtain background concentrations as well as the increase in these concentrations at the hypothetical scattering ellipse, of which various versions have been computed. For reasons beyond our control, the entire sampling operation had to be carried out on foot, with the consequence that the results lacked the necessary statistical buttressing and we were able only to discern the probable direction of the scattering ellipse, without any opportunity of describing the contours of the area. Figure 11 shows the actual sites at which the soil samples were taken. The areas of the stippled circles are proportional to the concentrations of magnetite spheres per arbitrary area unit (Table 4). If we average all of the data over the various distances from the epicenter, we obtain in complete agreement with theory the distribution shown in Table 5, which clearly characterizes the comparative sparsity of particles in the central section and their concentration at the periphery (see also Fig. 12c). This qualitative relationship fully explains the unsuccessful attempts on the part of previous expeditions to detect a noticeable concentration of meteoritic matter at the epicenter. A comparison of the northern and southern halves of the investigated area clearly shows the difference in the nature of particle distribution. The clearest results are given by averaging over quadrants (Fig. 12a, b).

As many as 90 magnetite spheres were found per unit area in the richest specimen - indeed, the only one - taken on the unflooded bank of the Chunya River (10 km above the mouth of the Kimchu River, 80 km north northwest of the epicenter). It is our opinion that the above relationship is not accidental, although it may be of inadequate statistical certainty. The meteorite's flight path from the southeast in the presence of a south-southeast wind might serve as an explanation, and it would also clarify the slight drift of matter from the meteorite train to the northeastern quadrant (Table 6), with the main mass of the explosion products falling farther to the north and northwest. The scarcity of meteoritic matter in the southwestern quadrant is characteristic. The indicated distribution pattern for meteoritic matter corresponds to the meteorite trajectory projected by Krinov and to the synoptic conditions of 30 June 1908 as per the data provided by the Central Weather Forecasting Institute. Zotkin accomplished the preliminary statistical evaluation of these materials. The histogram (Fig. 13) shows the distribution of 36 samples (n) as a function of the number (x) of spheres contained in the sample. If the fractional values of x are combined with the next-lower whole numbers for greater clarity, we obtain the following distribution of n with respect to x from the 28 poor samples (7 spheres or fewer): Number of spheres, x

0

1

2

3

4

5

6

7

Number of samples, n

4

13

5

3

0

2

0

1

Frequency, w

0.14

0.46

0.18

0.11

0.00

0.07

0.00

0.04

Probability, p

0.17

0.31

0.27

0.15

0.07

0.02

0.01

0.00

4.9

8.5

7.4

4.3

1.9

0.7

0.2

0.05

Number of samples expected from formula. n

s

It may be concluded that the poor samples pertain to the background. In this case, the fluctuations in the number of spheres in the sample must be subject to the Poisson distribution: p(x) = a(x) e

-a

........x!

where a is the average number (mathematical expectation) of spheres in the sample and p(x) is the probability of x spheres being present in the sample. The Poisson distribution gives the probability that a given number of events will occur in a given interval, provided that they are randomly distributed in the area being studied. The number of meteors noted during the course of a specific interval of time, for example, satisfies the distribution almost exactly. In our case we can assume that the cosmic spheres falling to the earth over an extended period of time will, in general, be uniformly and randomly distributed over its entire territory. From the preceding conclusion we find that the average a = 1.7 and that the dispersion d2 = 2.6. For this volume of statistical data a = d2 is a satisfactory test. This derivation uses probabilities p calculated from the Poisson distribution, and the theoretical number n of samples. Agreement with the empirical frequency s

w and the actual number of samples is also quite good. The probability of eight or more spheres appearing in the background samples is extremely small, i.e., p (x>8)