I have been clearing some of my land, and have been cutting and splitting the wood, about 30 cords so far. Anyway; this one tree is some of the hardest to split wood I have ever seen, bar none, elm, hickory, black Oak, etc. The outer one inch of the wood has a twist in the grain where's the center is straight grained. When you split it, the outer cracks at a point at the top and ends a third of the way around the perimeter, by the time it reaches the bottom of a sixteen inch piece of wood. Now imagine what is going on throughout the length of the tree, a barber pole... remember those. The outer inch is like a sheath, and tends to bust off the inner when split, crazy hard stuff to split, wedge loser, almost stops the hydaulic too.
I saved a couple of pieces, what could have possibly caused this internal growth deformity? Looked normal on the outside as far as I remember.