The Lavalite World by Philip José Farmer

1983

The fifth book in the World of Tiers series

The Lavalite world is a world of slow but constant change. Here mountains rise from plains, or sink into rifts; new oceans form as vast hollows collapse and seas rush in. There is only one escape from this world where the very landscape moves. The one gateway to other universes is in the palace of the Lord Urthona. Paul Janus Finnegan - also known as Kickaha - must reach it if he is to survive. And he must do so despite the Lords Urthone and Red Orc, the hired thug McKay, flesh-eating vegetation on the run, beasts of prey and planetary pseudopods