My supply for maybe 10 years from 2009 is the stumps of grubbed out old olive trees. There is no straight grain in these old roots and boles and they start off weighing anything up to about a ton and a half. Embedded stones and dirt make chainsawing dangerous, slow and expensive. Fortunately, although I am growing older (my three score years and ten are up next year)I am also growing bigger by the day swinging a big block splitter and using several steel wedges. Eventually brute force breaks everything - maybe even me someday.