The initial discovery was in March 1924 by Emile and Claude Fradin on their farm in the hamlet of Glozel near Vichy, France. When the cow pulling the plow got it's foot stuck, Emile and Claude extracted the cow's leg which lead them to an underground chamber where they found some ceramic fragments and human bones.
A subsequent excavation in April of 1924 revealed tablets, idols, bone and flint tools and engraved stones. In September 1925, the amateur archaeologist Antonin Morlet published his findings as "Nouvelle Station Néolithique" and declared that the site was Neolithic (7000 BCE - 1800 BCE). Controversy soon followed when the 'powers that be' dismissed Morlet's findings. Subsequent excavations have produced further artifacts and controversy.
Dating the pottery using modern methods has indicated that the artifacts fall into three age-groups. The oldest is 300BCE to 300CE, the second grouping was the 13th century, and the last group was found to be recent (20th century).
The 100 or so tablets have yet to be deciphered, but different experts have seen similarities between the characters and Phoenician or Basque or Chaldean or...(the list goes on).
Now the similarities between the writing on the Glozel tablets and writing discovered in Okinawa at or near the Yonaguni 'monument' is where the Glozel tablets intersect with James Churchward's theories on a lost Pacific Ocean continent. Actually, the phrase they use is 'common cultural origin' because they link the characters found at Yonaguni with the Glozel Tablets, the Phoenicians and writings discovered near Tiahuanacu in South America.
Fortunately, James Churchward's thoughts about the Glozel Tablets are known. As shown in the following page excerpted from one of James' scrapbooks, he wrote the word "Fake" and initialed it. A note of significance is that this image features reproductions from Morlet's "Nouvelle Station Néolithique". Click for larger size.
Here is another of article from James' scrapbook from September 11, 1926 on the "Glozel Discoveries". Click for larger size.
This is not to say that the tablets were fake, only that James Churchward's opinion of them was that they were fakes.
Further information:
Wikipedia
Dramatic story of the Glozel Tablets Controversy
Have a great day,
Jack Churchward
Clearwater, Florida