Bailey is a metallurgist who posits that there was not enough tin in the Old World to make all the bronze made during the Bronze Age, and that it was aquired from mines in the Andes and in Michigan (?) by ancient seafarers, who, by virtue of their wealth and power, were viewed as gods, all this 9,000 - 13,000 BC.
It would be interesting to see if technology is now able to "fingerprint" different metal samples and determine their origin, something that Bailey could not.
Other lines of "evidence" are the similarities of pyramids in the Near East and in South America; the relative ease of transoceanic travel compared to the dangers of navigating the Mediterranean; and the presence of Chinese junks in what is now Monterey Bay when Magellan arrived.
I don't think Bailey is taken seriously by historians, and some of his ideas may have been completely discredited by now, but the logic of his case is excellent reading, and a wonderful tour of what the ancient world may have been like. I'd like to know what other metallurgists and historians think of this book.