Rediscovering AmericaThe New World may be 20,000 years older than experts thought BY CHARLES W. PETIT Late in the afternoon last May 17, a tired archaeological team neared the end of a 14-hour day winching muck to the deck of a Canadian Coast Guard vessel. It was in water 170 feet deep in Juan Perez Sound, half a mile offshore among British Columbia's Queen Charlotte Islands. For four days, team members had fruitlessly sieved undersea mud and gravel. Then, in the slanting light of sunset, a deckhand drew from the goop a triangular blade of dark basalt. Its sharp edge...