And presumably, with a large enough team, the "track" could be lifted once the stone has gone over it, and relaid at the front JIT. I also think that the peopl

And presumably, with a large enough team, the "track" could be lifted once the stone has gone over it, and relaid at the front JIT. I also think that the people of the time were very adept at working with large tree trunks. Many late stone-age structures used them extensively, eg large round houses, platforms on lakes, etc. Fashioning smooth round rollers would have been relatively straight-forward for them IMO.