As I understand it, the wood from years ago, grown during the last little ice age, is so compact that it give great tonal qualities.
http://andrewolson.com/Neil_Peart/drums/drumkits/r40.htm
Neil Peart’s drums (RUSH) on their last tour were from a single log that fell in the year 500 into a bog and was buried by centuries of silt.
In another article about them when he went to test out another small kit made from the wood that they had set up in the factory. After 2+ hours of playing it was closing time - they told him to lock up when he was done.