This is a much better, and better organised, book than other reviews suggest. It may look, at the start, as if it's a Victorian pastiche fantasy involving the sudden replacement of an entire continent with new fauna/flora, suggesting a novel explanation for fossil evidence of earlier seemingly alien systems (not necessarily a theistic explanation). The real explanation, signalled early on, is a lot spookier and provoking. It wouldn't be fair to say what it is - but maybe a glance at [...] would help (or worry) once you've read the book! The author doesn't 'lose his way', and his characterization adds interest to what is already a good myth.