At the Earth's Core 1976

4,000 miles to the center of the Earth to a world within a world

Directed by Kevin Connor

A huge burrowing machine tunnels out of control at ferocious speed, cutting clean through to the center of the earth, to the twilight world of pellucidar. Once there, Dr. Perry and David Innes are threatened by half human creatures, lizard-like birds, and man-eating plants.