Yesterday I was exposing lava that flowed here 4,000 years ago (more or less; that's the USGS estimate for the Mauna Loa flow that underlies most of Pi'ihonua). There are parts of the yard that are boring grass when they could be nicely-varied with exposed lava, so that's what I'm doing. What's interesting here are the color variations (the top was an inch or two below the surface, and thus enough sunlight got in to blacken it; the front face was deeper in the soil and has the ruddy color expected of old lava). And notice the grass roots, how they have managed to attach to the lava surface -- and are beginning the process of turning lava into soil. Beginning is the key word. Even if I'd left it alone, it wouldn't have completed for centuries.