 In "Ragnarok", Donnelly argued that an enormous comet struck the Earth approximately 12,000 years ago, destroying an advanced civilization on the "lost continent" of Atlantis.Donnelly, following Halley and Whiston, attributed the Biblical Flood to this event, which he hypothesized had also resulted in catastrophic fires and significant climate change.Shortly after the publication of "Ragnarok", one commenter noted, "Whiston ascertained that the deluge of Noah came from a comet's tail; but Donnelly has outdone Whiston, for he has shown that our planet has suffered not only from a cometary flood, but from cometary fire, and a cometary rain of stones."