Atlanteans vs Roman Technology
The ditch surrounding the Plain of Atlantis was found to be ‘incredible’ by Plato (Crit.118c), it is worth comparing it with one of the most extensive ancient ditch systems still visible to day.
While the length of the ditch is remarkable, but being a stade (600ft) in width and a plethrum (100ft) deep, it amounts to a cross section of an astounding 60,000 sq ft. It brought to my mind the Fossatum Africae, which was a defensive ditch over 600 km long delineating the southern limit of the Roman Empire in what is now Algeria and Tunisia. This feature was rediscovered in 1947 by Jean Baradez, a retired French Air Force pilot and described in great detail in his 1949 book, Fossatum Africae. While the depth and width of the fossatum varies considerably, they are approximately 10ft x 10ft, which would give an average cross section of just 100 sq ft.
This means that the Atlantean ditch described by Plato would have been 600 times greater in cross section than the best produced by the might of the Roman Empire. A rough graphical depiction is given in the paragraph above, where the initial letter ‘W’ represents the cross section of the Roman fossatum, while the entire paragraph represents the presumed dimensions of the perimeter ditch surrounding the plain of Atlantis. Also keep in mind that the effort required to raise earth from a depth of ten feet becomes exponentially greater the deeper you go, so that the manpower required excavating the Atlantean ditch would be many thousands of times greater than that required for the fossatum. No wonder Plato found the dimensions passed to him by Solon ‘incredible’.
The illustration above should convince any reasonable person that Plato’s numerical data, at least in this instance, is greatly exaggerated.
Henri-Paul Eydoux has also written a chapter on this African feature [927.171].
The Plethrum is a Greek measurement of 100 Greek feet in length (101 English feet) as well as 10,000 sq.ft. in area. It and its plural, plethra, is used in four instances in Critias (115d, 116a, 116d and 118c).
It is interesting to note that in one case (118c) Plato found the dimensions of 10,000 stade ditch surrounding the plain of Atlantis as very hard to believe but felt obliged to record it out of deference to the reputation of his source, Solon. The text states that this ditch was dug by hand to a depth of a plethrum and a stade in width.
He was forced to make this suggestion because he recognised that the dimensions for the plain of Atlantis as recorded by Plato must have been exaggerated. However, when it came to the ditch which surrounded the plain he was also contented to accept that the stade width of the ditch was excessive but that the plethrum depth was acceptable because the clay banks would have been continually subject to slippage! Feasible, but for me, not totally convincing.