As search of the web turns up 58 hits for the Nacaal Tablets and 222 hits for Nacaal. Some say the tablets were lost in the 1920's after Churchward died, some say their are still supposed Nacaal language tablets extant in Tibetan Monasteries. I haven't referenced the books yet.

Another gentleman, Harold Handley Copeland, a respected Cambridge University archaeologist known for his Pacific Studies also cites a study of tablets in the Nacaal language he calls the Zanthu Tablets (after the name of the scribe who wrote them):
http://www.disorganization.com/Library/ZanthuTablets.html

These examinations of the Lemuria (Mu) are, of course, theoretical archaeology with, like Atlantis, just enough credible evidence to keep the books open.

As a paleontogy buff I am well-enamored of the work of the Leaky clan in Africa, and support the fossil record of that evolutionary theory, which probably points to the "Eve" link on that continent in the evolutionary process several million years ago. But I'm not so sure, from arcaheological and historical evidence I have see (including the writings of Plato) that there weren't some lost civilization(s) circa 50-100,000 B.C. before the dawn of 'recorded' history. (Oh, if only that damn Roman general didn't burn the Library of Alexandria just to piss-off Cleopatra!) Many common myths, symbols, artwork, ceremonies, and practices by disparate peoples of antiquity across all continents (Asia, South and Central America, Europe) who could not possibly have communicated in that far dawn of history point to a common source. The myth or story of the "Great Flood or Deluge" being one of the most obvious. The Jungian theory of mutual myth arising from the Collective Unconscious can account for some of it, I believe, but not all of it.