UNLIKE SOME OF THE "FACTS" I'VE HEARD ON P B S, I KNOW FOR A FACT IT DOES NOT TAKE 10s OF THOUSANDS OF YEARS TO PETRIFY. OUR HOME WAS BUILT IN 1960. WE BOUGHT THE HOME IN JUNE 2010. AROUND OCTOBER WE FOUND A PIECE OF FORMING LUMBER ALONG SIDE OUR DRIVEWAY ALONG WITH A PIECE OF NEARLY DETERIORATED LUMBER. THE PIECE THAT HELD TOGETHER WAS HEAVY, VERY HARD (PETRIFIED) AND HAD HAD A METAL RING TO IT WHEN STRUCK. METAL RING SOUND. IT HAD BEEN SAWED PERFECTLY TO BUTT UP NEXT TO THE OTHER PIECE. 2010-1960=50.
SO I GUESS MY ANSWER WOULD BE 50 YEARS OR LESS. WHY THE PIECE NEXT TO IT WAS DETERIORATED?????I DON'T KNOW. GOD BLESS. HOPE THIS ANSWERS YOUR ?

Over 1000 years :o