Just got back from Lanzarote and was walking through a recent (300yr old Timenfaya) lava field. Very little rain in 300 years so it's more or less like it started, I guess. A great landscape to investigate the way volcanic landscapes develop. What I couldn't understand was the structure of the surface in places. It looked as if a giant JCB had been breaking up turning over a layer of concrete - or possibly a plough in a clay field. The surface consisted of large broken fragments (many, at least a metre diameter), with lots of air gaps underneath. I couldn't figure out what mechanism lifted the lumps so far above the mean ground level. The field was more or less horizontal so it wasn't as if they had rolled downhill or been carried like the lumps of granite in Snowdonia etc. Also, there seemed to be dunes of fine stones - a la Sahara but the wind would need to have been v. strong to form them with such large particles. Someone must have worked it out. . . . .