I believe that Admiral Byrd, being a Freemason, is either lying or exaggerating about the extra land across the "South Pole." What if the extra territory are uncharted continents/islands in the Pacific, Atlantic and/or Indian Oceans. Shipping lanes and air lanes could hide this land.

Also, we don't know for sure that Mount Everest existed before the Flood as we know it now at 34,000 feet above sea level. What if it was much smaller before the Flood?

Also, after God confounded the languages after the Tower of Babel, there was a fellow named Peleg (Gen 10:25 Peleg means earthquake) who was born when God divided the one land mass into the several continents we know of today.