L. Sprague de Camp delivered a devastating verdict on Fessenden in his Lost Continents, calling it “dubious geology, bad mythology, impossible linguistics, and Aryan-race nonsense.”
Fessenden has an undeserved reputation for scholarship since his cranky ideas captured the fancy of Flinders Petrie in 1924, then laboring under the false idea that the Solutrean stone culture of the Ice Age was the antecedent of both Egypt and Caucasian culture. Unbeknownst to Petrie, the Solutrean dates back to 19,000 BCE, and only in Western Europe, far too early to posit a significant cultural relationship between the Caucasus and Egypt.
But what interested me was Fessenden’s misuse of ancient texts. The clearest example comes in his 1933 set of chapters. There he quotes Sanchuniathon and Berossus and attempts to make them support his views. Fessenden, whose use of primary sources extended little farther than his copy of Cory’s Ancient Fragments (his acknowledged source), showed no familiarity with the Babylonian texts Berossus used as his sources and which available in English since the 1870s. This was quite odd since in another chapter he discusses the names of the Babylonian gods and tries to make them into Armenian mountains. No matter. This is what Fessenden wrote of Berossus:
Here’s what I think Fessenden saw. He read about Oannes, the being described as one “whose whole body (according to the account of Apollodorus) was that of a fish; that under the fish's head he had another head, with feet also below, similar to those of a man, subjoined to the fish's tail.” and then saw this passage: “After this there appeared other animals like Oannes, of which Berossus proposes to give an account when he comes to the history of the kings.”
From this, I think he read into it the idea that a “fish-man” was a reasonable description of a seal—ignoring the fact that Oannes not only talked but also taught agriculture, architecture, and science. Thus, the appearance of many Oannes-like creatures became for him seals populating the sea. But the sea in which Oannes appeared was the “Erythræan Sea,” a term used variously to refer to the Red Sea, Persian Gulf, Arabian Sea, or Indian Ocean in ancient times.
At any rate, no one needs to take my word for it. All of Berossus is online, and you can buy your own copy in my edition of Cory’s Ancient Fragments. It’s one of the wonders of the internet: now everyone can check references to see just how wrong alternative authors are.