The Hollow Earth

Description for THE HOLLOW EARTH by Rudy Rucker: 

Interweaving history with science fiction, this adventure--set in the pre-Civil War South--features Edgar Allan Poe and two cohorts exploring the exotic lands of Earth's core and discovering a parallel universe.

In 1836, Mason Algiers Reynolds leaves his family's Virginia farm with his father's slave, a dog, and a mule. Branded a murderer, he finds sanctuary with his hero, Edgar Allan Poe, and together they embark on an expedition to the South Pole. It is there where strange people, and stranger creatures abound, that their bizarre adventures truly begin.