The GCD is down right now, so I can't check the artist, but it's a beautiful cover with terrific inking and dynamic perspective. This is a classic DC "puzzle" cover, where the goal was to get the kid to pick up the comic and find out how exactly the earth managed to get sliced in half like an orange.
Update: As pointed out by my old buddy Snard in the comments, the cover is by Gil Kane, one of the more prolific artists of the Silver Age.
