Jose D.C. Hernandez wrote an extensive article for the world-mysteries website in 2013, entitled A Celestial Impact and Atlantis(a). In this fully illustrated paper he outlines his belief that an impact around 12,000 years ago was responsible for the biblical Deluge, the creation of Australia and the destruction of Atlantis. He specifies the Richat Structure in Mauritania as the remains of Atlantis.
Antoine Gigal is a French researcher, probably best known for her work on the pyramids of Sicily described on her multilingual and well illustrated website(a). Her first love is clearly ancient Egypt, a passion that is evident throughout her website. She includes an interesting article on the method used to build the Great Pyramid proposed by Hasan Sayid Ahmad, which involves the use of sledges in the internal ascending passage(d).
She has only touched on the subject of Atlantis, apparently accepting its existence without involving herself in discussing any specific aspects of the story. An example of this is to be seen in her article on the Richat Structure(b).
Gigal was also a founder of the Giza for Humanity website(c).
George S. Alexander and Natalis Rosen have established a website(a) promoting the Richat Structure, in Mauritania, as the location of the city of Atlantis. They are not the first to make this suggestion but have at least visited the site in 2008 to gather evidence to support their contention. Their expedition formed the basis for a free one hour video(b). Like supporters of various other locations theories, Alexander and Rosen have managed to match some of the details in Plato’s description with features in the Richat area.
The Richat Structure is around 35 km in diameter yet no evidence whatsoever of buildings whatsoever was found. In my opinion Alexander & Rosen have not satisfactorily explained this absence. Apart from that, a city with a diameter of 35 km is not credible in the timeframe proposed by them.
Salt Domes are the result of large deposits of salts laid down millions of years ago and subsequently covered by layers of sediment that in time became stratified rock. Over time the deposits push upwards, as they are usually less dense than the overlying rock, creating domes. Erosion of these domes can produce a feature that has the appearance of a series of concentric circles. These domes can be many kilometres in diameter and in Kazakhstan have been numbered at 1,200.
Salt domes have been recently put forward as an explanation for the circular waterways of Atlantis, as described by Plato. Ulf Richter has proposed(a) that if one such dome had originally been overlaid with strata of varying hardness the effects of erosion could have produced a number of concentric depressions that could have been adapted as canals. Richter provides a diagram demonstrating the process and gave the Richat Structure in Mauretania as a good example of the process.
The Sahara Desert and in particular its northern regions have attracted its share of attention from Atlantis investigators. However unlikely it may appear as a possible location for Atlantis it must be kept in mind that the Sahara of prehistory was very different from what we see today. Not only was it wetter at various periods in the past, but also there is clear evidence for the existence of a large inland sea extending across the borders of modern Algeria and Tunisia. This evidence is in the form of the chottsor salt flats in both countries. This proposed sea is considered by some to have been the Lake Tritonis referred to by classical writers. It is suggested that some form of tectonic/seismic activity, common in the region, was responsible for isolating this body of seawater from the Mediterranean and eventually turning it into the salt flats we see today.
An even more extensive inland sea, further south, was proposed by Ali Bey el Abbassi and based on his theory a map was published in 1802 which can be viewed online(c).
More recently, Riaan Booysen has published an illustrated paper on the ancient inland Saharan seas as indicated on the 16th century maps of Mercator and Ortelius(i). King’s College London runs The Sahara Megalakes Project which studies the Megalakes and the Saharan Palaeoclimate record(m).
A 2013 report in New Scientist magazine(d) revealed that 100,000 years ago the Sahara had been home to three large rivers that flowed northward, which probably provided migration routes for our ancestors.
Other studies(h) have shown the previous existence of a huge river system in the Western Sahara, which flowed into the Atlantic on the Mauritanian coast.
An article in the Sept. 2008 edition of National Geographic pointed out that the Saharan climate has been similar for the past 70,000 years except for a period beginning 12,000 years ago when a number of factors combined to alter this fact. A northerly shift by seasonal monsoons brought additional rain to an area the size of contiguous USA. This period of a greener Sahara lasted until around 4,500 years ago. Henri Lhote contributed an article to the Reader’s Digest’s, The World’s Last Mysteries , regarding the ‘green’ Sahara that existed prior to 2500 BC.
An interesting question might be; what happened circa 2500 BC to cause this reversal? Some have suggested a connection between the aridification of the Sahara and the destruction of Atlantis!
More recently, human activity has been blamed as a major contributory factor for the desertification of the Sahara region less than 10,000 years ago.(n)
Related to the above is a recent study of sediments off the west coast of Africa, which resulted in the discovery of what was “primarily a new “beat,” in which the Sahara vacillated between wet and dry climates every 20,000 years, in sync with the region’s monsoon activity and the periodic tilting of the Earth.” (o)
In 1868, it was proposed by D.A. Godron, the French botanist, that the Sahara was the location of Atlantis. In 2003, the non-existent archaeologist Dr.Carla Sage announced that she was hoping to lead an international expedition to the Sahara in search of Atlantis. Her contention was that “Atlantis was the capital of a vast North African empire with ports on the Gulf of Sidra”. This report is now confirmed to have been a hoax! I am indebted to Stel Pavlou for uncovering the origin of this story(e).
Gary Gilligan, the well-known catastrophist, wrote a thought-provoking article(k) on the origin of the Saharan sands, which he claims are extraterrestrial in origin and expands on the idea in his 2016 book Extraterrestrial Sands .
David Mattingly, an archaeologist at Leicester University has found that an ancient people known as the Garamantes had an extensive civilisation in the Sahara(l). He has evidence of at least three cities and twenty other settlements. The Garamantes reached their peak around 100 BC and then gradually diminished in influence as fossil water supplies reduced until in the 7th century AD they were subjected to Islamic domination. Some researchers such as Frank Joseph have identified the Garamantes as being linked with the Sea Peoples. Bob Idjennaden has published short but informative Kindle books about both the Garamantes  and the Sea Peoples , without a suggestion of any connection between the two.
The discovery of the megalithic structures discovered at Nabta Playa (Nabta Lake) in the Egyptian Sahara has provided evidence for the existence of a sophisticated society in that area around 5000 BC. In the same region, near the Dakhleh Oasis, archaeologists have produced data that supports the idea that pre-Pharaonic Egypt had Desert Origins rather than being an importation from Mesopotamia or elsewhere(a).
Nabta Playa is not unique, in fact the largest megalithic ellipse in the world is to be found at Mzorah, 27 km from Lixus in Morocco(b). It appears that the construction methods employed at both Mezorah and Nabta Playa are both similar to that used in the British Isles. An even more impressive site is Adam’s Calendar in South Africa which has been claimed as 75,000-250,000 years old.
West of Cairo near the border with Libya is the Siwa Oasis, where it has now been demonstrated that “it is in fact home to one of Ancient Egypt’s astounding solar-calendar technologies– the solar equinox alignment between the Timasirayn Temple and the Temple of Amun Oracle in Aghurmi.”(j).
I think we can expect further exciting discoveries in the Sahara leading to a clearer picture of the prehistoric cultures of the region and what connections there are, if any, with Plato’s Atlantis. In the meanwhile in the Eastern Egyptian Desert, Douglas Brewer, a professor of archaeology at the University of Illinois, has discovered over 1,000 examples of rock art, including numerous depictions of boats although the sites, so far undisclosed, are remote from water.
Even more remarkable is the report(e) of March 2015 that a survey of the Messak Settafet escarpment in the central Sahara revealed that there were enough discarded stone tools in the region “to build more than one Great Pyramid for every square kilometre of land on the continent”! Coincidentally, around the same time it was reported that over a thousand stone tools had been found in the Northern Utah Desert(g). What the Utah discovery lacked in quantity was made up for in quality with the finding of the largest known Haskett point spear head, measuring around nine inches in length.
(a) Saudi Aramco World (2006, Vol. 57, No.5 p.2-11)
(d) NewScientist.com, 16 September 2013, http://tinyurl.com/mg9vcoz
(l) See: Archive 3268