Tarzan at the Earth’s Core

Tarzan at the Earth’s Core was published in 1930 and is the major crossover novel that links the Tarzan series with Burroughs’s other big franchise, the Pellucidar sequence of novels set inside a hollow Earth. Tarzan is recruited by a German explorer named Zuppner to take a giant airship into the polar opening that leads down to the inner-Earth country of Pellucidar, where Burroughs had previously sent his adventurer David Innes in earlier books.

Inside Pellucidar Tarzan finds the world without time, a country of perpetual noon, dinosaurs, intelligent primitive humans, and a slave-trading Mahar reptilian intelligence. The airship is wrecked. Tarzan must work his way across the unfamiliar environment to find and rescue the original expedition. Some readers consider the crossover gimmicky. Others love the way it expands the Burroughs universe. The Pellucidar sections give Tarzan a chance to be the unfamiliar one in an environment he cannot easily dominate, which is rare in the series and welcome.