Darwinia
From the back cover:

In 1912, history was changed by the Miracle, when the old world of Europe was replaced by Darwinia, a strange land of nightmarish jungle and antediluvian monsters.  To some, the Miracle is an act of divine retribution; to others, it is an opportunity to carve out a new empire.

Leaving an America now ruled by religious fundamentalists, young Guilford Law travels to Darwinia on a mission of discovery that will take him further than he can possibly imagine... to a shattering revelation about mankind's destiny in the universe.
Imaginary histories, Science fiction, Fiction, Fiction, science fiction, general, Fiction, alternative history
Robert Charles Wilson