Major speculative locales as Atlantis, Mu, and Lemuria are covered in depth, with the origins of lesser-known ones such as Thule, Hyperborea, and Rutas also treated.

The work shows how the misinterpretation of Mayan writings created the Mu myth, and how the name Lemuria originated from the geological hypothesis about a land bridge between India and South Africa.

The 1970 edition was updated to reflect the rehabilitation of Alfred Wegener's continental drift theory and investigation of the ancient volcanic eruption of the Aegean island of Thera.

Lost continents or ancient civilizations sunk by a deluge are a common theme in the scriptures of doctrines of many modern pseudoreligions or cults.

Well-known instances include James Churchward's books on Mu, the Theosophical portrayals of Hyperborea, Lemuria and Atlantis, and even the Nazi mythologizing about Thule.