Art identification based on how the rocket and smoke on this cover is consistent with how they’re drawn on Stoner’s signed cover for Rocket Kelly #5 (October, 1946).
Rocket and his friends discover the prehistoric Lost Sky-World in the Andes mountains. Stranded explorer Evanson says the inhabitants plan to take over the Earth with their fantastic inventions, including "atomships" and giant insects. Rocket destroys them all.
Rocket Kelly; Punchy; Diana; Professor Kelly; Professor Marco
Synopsis
Rocket and his friends aid his father and Professor Marco in a project to reclaim the desert of Egypt. However, Professor Marco tries to sabotage the project and kill Rocket and the others, because there is valuable uranium under the desert. Marco dies and "the desert shall bloom" (or at least glow with radioactivity).
Kit wants to win a prize silver saddle for performing a deed of valor. He eventually gets it by rescuing young Marybelle from drowning, after an eagle drops her in a river.