We have now hit ice so thick I cannot drill through it with an 8 inch long wood bit. The first 4 inches are the refrozen junk, below that is the solid stuff. Interestingly no cracks in the surface due to the junk full of air vs. Last year's black ice with gaping maws that ate ice skates. So while the ice is soft and digs up easily while skating, it doesn't eat your skate.
