Martin B. Sweatman is a geochemist at the University of Edinburgh who gained wider recognition with the publication of PreHistory Decoded  in 2019. In it, he discusses many subjects dealt with in this compilation, such as Göbekli Tepe, Younger Dryas, and the Sphinx offering what the book’s subtitle describes as “a science odyssey unifying astronomy, geochemistry and archaeology.”
Building on the work of Clube & Napier he believes that around 10,900 BC an encounter with a fragment of Comet Encke led to catastrophic climate change of the Younger Dryas and kick-started the Neolithic Revolution. After an in-depth study of the carvings at Göbekli Tepe, he believes that they record astronomical events and in a 2017 joint paper with Dimitrios Tsikritsis, published in Mediterranean Archaeology and Archaeometry, (Vol.. 17, No 1) they offer an illustrated outline of this theory(a)
Sweatman had previously used his scientific training to decode an early zodiacal system found across western Eurasia, from European Palaeolithic caves to sites in Turkey, Egypt and Mesopotamia. He has now gone one step further by linking Pictish symbols to this system.(b)
For balance, I offer a link to a critical review of Sweatman’s theories(c).
The Younger Dryas Impact Hypothesis (YDIH) is based on the claim that around 12,800 years ago the Earth had an encounter with a very large asteroid or comet that broke up in an airburst over North America and of which some fragments possibly hit the ground directly(a).
Many effects have been linked with this event with varying levels of enthusiasm including a suggested association with the demise of Atlantis. Elsewhere, megafaunal extinctions, cataclysmic floods, the disappearance of the Clovis people and the creation of the Carolina Bays(g), have all been proposed as consequences of this episode.
In 2006, Richard Firestone, Allen West & Simon Warwick-Smith published the foundations of the YDIH in The Cycle of Cosmic Catastrophes . A year later the hypothesis had a more public airing at the American Geophysical Union Press Conference, Acapulco, Mexico, May 23(d). This was followed the same year by the publication of a formal paper in the Proceedings of the National Academy of Sciences of the United States of America(f).
Since then volumes have been written on the subject, both pro and con(c).
A 2014 paper(h) entitled Nanodiamond-Rich Layer Across Three Continents Consistent with Major Cosmic Impact at 12,800 Cal BP by Charles R. Kinzie et al., has developed further the idea of this event being associated with the Younger Dryas. In a similar vein is an article(f) from Megan Gannon.
December 2014 saw Graham Hancock raising the issue of a cometary cause for the Younger Dryas and its possible association with ancient Egypt(e).
Martin Sweatman brought further evidence to bear on this debate in an article(i) on the Graham Hancock website. This focuses on the investigations at Hall’s Cave in Texas described in a paper by Sun et al, where the team concluded that the trace elements found there could indicate a volcanic rather than an impact as the cause of the Younger Dryas cooling! Sweatman disagrees with their conclusions claiming that there seems to be an element of selectivity in choosing data, leading to a wrong conclusion.
>2019 also gave us a paper that included an extensive bibliography and overview of the YDIH debate(k).<
In 2020, the eminent geologist James Lawrence Powell published Deadly Voyager , which offered further support to the YDIH. This book was instrumental in changing the negative stance of a number of ardent sceptics including Michael Shermer(j).
Archaeoastronomy is a relatively new scientific discipline, which as the name implies combines archaeology and astronomy, particularly in the study of ancient megalithic monuments and their possible alignment with various celestial bodies.
Arguably the most famous example is Stonehenge, but our globe is littered with ancient monuments incorporating solar, lunar or astral alignments. Not all are as impressive or accessible as Stonehenge, Callanish or Newgrange but in remote places such as Nabta Playa or Fajada Butte (see Hadingham[1308.152]).
The subject was initially considered by some to be a ‘fringe’ topic, but in 1999 Clive Ruggles was appointed Professor of Archaeoastronomy at the University of Leicester(a) and is the author of the encyclopedic Ancient Astronomy.
The University of Maryland has had a Center for Archaeoastronomy since 1978(c).
The subject has never been central to Atlantis studies but has hovered in the background, with writers such as Egerton Sykes(b) and Graham Hancock who employed aspects of the discipline in their publications.
Giulio Magli (1964- ) is an Italian archaeaostronomer with a website in English(e) dedicated to the application of the discipline in Egypt. In 2013, Magli proposed that aspects of the Göbleki Tepe site are related to the recent appearance of Sirius in the night sky around 9300 BC(f). Andrew Collins and Rodney Hale argue against this interpretation(g), which is perhaps understandable as they support a linkage with the Cygnus constellation. A 2004 paper by Magli, on precessional effects in ancient astronomy(h), has recently been applied by Lenie Reedijk to her contention that the Maltese temples were oriented to Sirius.
A further application of the discipline was employed by Martin Sweatman and Dimitrios Tsikritsis who used it to interpret the carved symbols at Göbekli Tepe. In a 2017 paper(d) they concluded that the pillars there were used to record meteor showers and cometary encounters. They believe that one such encounter involved the explosion or impact of part of Encke’s Comet around 13,000 years ago, which triggered the Younger Dryas Event that kick-started the Neolithic Revolution. Scientists who have worked on the site responded critically(i), which in turn evoked further comments from Sweatman and Tsikritsis(j).
Sweatman later expanded their theory in his book Prehistory Decoded .
The Sixth Oxford International Conference on Archaeoastronomy and the Seventh Annual Meeting of the Société Européenne pour I’Astronom~e dans la Culture (SEAC, European Society for Astronomy in Culture) was held jointly on the days around the summer solstice of 1999 at the Museo de la Ciencia y el Cosmos, in the historical city of La Laguna, in the island of Tenerife. One hundred participants from more than 20 countries of the five continents and almost 60 talks indicate undoubtedly the relevance of this meeting. The Proceedings of that Conference are available online(l) offering a global view of the subject.
Noah Brosch of Tel Aviv University offers a wide-ranging paper on the ancient sites and artefacts around the world that clearly had astronomical functions(k).
Archaeoastronomy is one of only a few dozen words with four consecutive vowels.
(j) https://www.academia.edu/33931844/MORE_THAN_A_VULTURE_A_RESPONSE_TO_SWEATMAN_AND_TSIKRITSIS (See the end of the paper)
Younger Dryas is also known as Dryas III was a mini Ice Age that lasted from around 10,700 BC until around 9600 BC. It is named after a wildflower called Dryas octopetala that flourished during this relatively short period. In Ireland, the period is known as the Nahanagan Stadial and in Britain as the Loch Lomond Stadial. For about thirteen hundred years the glaciers had been slowly retreating until within a short timespan temperature dropped and they began to advance again. The cause of this cooling is not entirely clear. One view is that a sudden release into the North Atlantic of vast quantities of freshwater that had been contained by huge ice dams is assumed to have closed down the Gulf Stream, resulting in a twelve hundred year lowering of global temperatures. There is evidence that the change only took one or two decades. The same threat is said to exist today with the possibility of the melting of the Greenland ice cap. It also seems that this YD cooling ended with the same rapidity.
A recent application of archaeoastronomy by Martin Sweatman and Dimitrios Tsikritsis led them to conclude that the carved symbols at Göbekli Tepe recorded an encounter involving the explosion or impact of part of Encke’s Comet around 13,000 years ago, which triggered the Younger Dryas Event that provided the impetus for the Neolithic Revolution. Sweatman later expanded their work in his book Prehistory Decoded  and an article on the Ancient Origins website(k). In June 2021, Sweatman had a paper entitled ‘The Younger Dryas impact hypothesis: review of the impact evidence’ published in the journal ‘Earth Science Review’ of the University of Edinburgh(u).
Kevin A. & Patrick J. Casey maintain that a globally catastrophic event occurred 13,000 years ago(j). The kernel of their theory is that originally the Earth had two moons that at some later point collided, producing our current Moon, while the remnant of the second one eventually exploded over North America kick-starting what we refer to as the cooler Younger Dryas period. They are adamant that it was not a comet or asteroid that caused the devastation, and so clash with the conclusions of Richard Firestone and his colleagues.
A completely different view is expressed in Rod (Carl) Martin’s latest book , where he proposes that the Younger Dryas ended as a result of a catastrophic event. Is it possible that there were two cataclysmic episodes? John Ackerman, a keen follower of Immanuel Velikovsky claims that there were two such events related to “the capture of the Moon into its current orbit,” marking the beginning and the end of the Younger Dryas period(q).
A somewhat technical paper, published in July 2020, challenges the comet impact theory because of geochemical anomalies, Instead, they argue that the YD event was a consequence of volcanic activity(s), rather than an impact! Martin Sweatman refutes this in a paper on Graham Hancock’s website(i).
In 2015, a paper constraining the impact date to within 100 years using Bayesian statistical analyses, now proposed as 12,835 -12,735 years ago(h).
Coincidentally, Emilio Spedicato independently concluded that it was a cometary impact in the North Atlantic that was responsible for the Younger Dryas. Subsequently, when temperatures rose again it resulted in the flooding of vast areas of low-lying landmasses that in Spedicato’s opinion included Atlantis, which he locates in Hispaniola.
Conflicting evidence regarding the possibility of the Younger Dryas being caused by such an impact is impartially outlined on the internet(a).
The November 2013 issue of the BBC Focus magazine (p.30) had a brief article on the impact theory, noting that the northern hemisphere saw a drop of as much as 15°C around 11,000BC. In the absence of a suitable impact crater of the right age, there is still much scientific scepticism(b).
However, in early 2017, further possible evidence of an impact at the start of the Younger Dryas was offered by a team led by Christopher Moore of the University of South Carolina, when they identified a distinct layer of platinum in the soil that coincided with the start of YD. Commenting on this anomaly Moore noted that “Platinum is very rare in the Earth’s crust, but it is common in asteroids and comets.”(e) In 2019, Moore published further data(m) supporting the extraterrestrial impact theory, based on studies carried out on sediments, which date back 20,000 years, from White Pond Lake, situated in southern Kershaw County, South Carolina. “Other examples of excessive platinum grains have been found across Europe, western Asia, Chile, South Africa(r) and North America.” (n)
In early 2018, two papers were published online(i), reinforcing the YD impact theory and adding evidence that the event resulted in a conflagration that “may have consumed ~10 million km2, or ~9% of Earth’s terrestrial biomass.” Related to this is a paper by Andrew Collins that draws attention to the ‘Usselo horizon’, a charcoal-rich layer of between 1 and 8 inches, found on all continents, indicating widespread fires, now dated to 12,900 years ago(l).
Ice cores from Greenland indicate a further cooling period circa 6200 BC that may be related to the abandonment of many Neolithic settlements during this period. Other periods of abrupt climate change have been identified from 3800 BC to 3500 BC and 2800 BC to 2000 BC.
The fact that Plato’s apparent date for the demise of Atlantis, circa 9600 BC, roughly corresponds with the current, best estimate for the date of the Younger Dryas is interesting but unfortunately not conclusive proof of any direct connection. In the absence of any supportive archaeological evidence, a linkage between Atlantis and the Younger Dryas will have to remain a matter of faith rather than fact. Interesting but inconclusive.
In 2017, Graham Hancock reviewed the Younger Dryas debate over the previous decade in a lengthy essay(v). This was prior to the publication of America Before. He finished with the following comment. “Perhaps the lost civilization that I have spent the last quarter of a century trying to track down had its most significant outpost, possibly even its heartland, in North America in the period BEFORE the Younger Dryas cataclysms of 12,800 to 11,600 years ago?” Hancock is inferring here that there was a single global civilisation, a hyperdiffusionist stance that I consider indefensible.
A short paper by John Patrick Hill offers a theory that requires more than faith to accept it; he wrote “Just over 12 thousand years ago, the world was struck by an immense meteor group. It destroyed all of North America and much of Europe and went weIl beyond……… I found proof to support that the creators of the Giza Three and Stonehenge used the Barringer Crater in Arizona as part of the geometry for their massive structures.” Later he reveals that at “Giza, when one takes the distance between the outside corners of the three large pyramids there, that distance is equal to 0.72 miles, the exact distance (diameter) at Barringer.” An expanded version of his paper is available online.(t)
Recent discoveries in northern Sudan of dozens of skeletons, the majority of whom were killed by flint-tipped arrows, have led to the suggestion(c) they were the result of food shortages resulting from the Younger Dryas that in turn led to warfare over diminished food availability.
I note that Robert Schoch claims that there is no evidence to support the Younger Dryas impact theory, instead, he believes that “it was most likely due to reduced solar activity at that time, a solar shut-down.”(o) Schoch’s wide-ranging critique has been refuted by the Comet Research Group.(p)
In 2020, James Lawrence Powell (1936- ), a noted geologist, author, former college president and museum director entered the Younger Dryas debate with the publication of Deadly Voyager . In it, Powell offers wholehearted support to the Younger Dryas Impact Hypothesis (YDIH), understandably generating a favourable review from Graham Hancock(w).
>Even more important, is that Powell’s book induced a number of heavy-duty critics of YDIH, including Michael Shermer to change their opinion(x).<
Encke’s Comet has the shortest orbital period of just over three years and was the second comet after Halley’s to have its period determined. It is named after the German astronomer Johann Franz Encke (1792-1865) who announced its periodicity in 1819. More information about Encke’s Comet is available on Kevin Curran’s website(f), which promotes his book, Fall of a Thousand Suns, in which he analyses the effects that cometary encounters have had on religious beliefs.
One website(c) suggests that Encke was only part of an even larger comet, proto-Encke, sometimes identified as Tiamat in Babylonian mythology and that Encke gave birth to the Taurid meteor shower.
Victor Clube and Bill Napier published their groundbreaking book in 1982 in which they identify Encke’s Comet or more correctly its larger progenitor as having had catastrophic close encounters with the earth in the past. They expanded their book in 1990.
Martin Sweatman is a University of Edinburgh scientist and the author of Prehistory Decoded . Building on the work of Clube & Napier he believes that around 10,900 BC an encounter with a fragment of Encke that led to catastrophic climate change of the Younger Dryas and kick-started the Neolithic Revolution. After an in-depth study of the carvings at Göbekli Tepe he believes that they record astronomical events and in a 2017 joint paper with Dimitrios Tsikritsis, published in Mediterranean Archaeology and Archaeometry, (Vol. 17, No 1) offers an illustrated outline of this theory.(g)
A number of investigators, including Frank Joseph have adopted their findings and have attributed the destruction of Atlantis, among other disasters, such as the eruption of Thera, to the repeated near misses by proto-Encke. In his latest literary recycling Joseph claims that Comet Encke in 1198 BC “scores a number of meteoric hits along the Mid-Atlantic Ridge and possibly on Atlantis itself, which perishes ‘in a single day and night’, according to Plato. The catastrophe is global, encompassing the destruction of the biblical Sodom and Gomorrah.” Joseph bases this claim on the conclusions of two Swedish geologists, Thomas B. Larsson and Lars Franzén.
Another writer, Martin Gray, claimed that in 3113 BC proto-Encke collided with asteroids in the asteroid belt between Mars and Jupiter causing extensive meteor showers that punctuated the Bronze Age, including the partial destruction of Atlantis(a) . Without hard evidence we must treat this as nothing more than interesting conjecture.
A fully illustrated article detailing an encounter with Comet Encke is offered by Stuart Harris(b) who dates this event to 8366 BC and which led to catastrophic destruction across Europe. Harris also offered the possibility of a return visit during August-September 2012, if the Cluster still exists. He added further data in 2013(d).
Graham Hancock has gone further and suggested that 2030 will possibly have another catastrophic encounter with Encke, hidden in the Taurid meteor shower. This ‘prediction’ in his Magician of the Gods(e) will do no harm to sales figures!