I'd like to ask you to help me identify a sci-fi/fantasy book that I read probably sometime in the 90s though I don't know when it was written. Here are the plot points that I remember:
- the story starts with a human on contemporary Earth being turned to stone (or probably something much more exotic) by some sort of experiment gone wrong,
- he is turned back to his original form millions of years later by a lightning or some similar phenomenon,
- the local population considers him a god or a prophet since his "stone form" was a center of a cult before he was awaken,
- the population is not human but consists of creatures evolved from various contemporary animals,
- one of the most important locations is a huge tree which is so ridiculously big that it contains multiple settlements.