Tom Brevoort starts a series of posts about comic book covers on his blog:
The earliest comic book covers were a pretty straightforward outgrowth of the lurid Pulp Magazines of the 1930s, much as the content of the comics took its cues from the sorts of adventure stories persented in such magazines. In the really early days, your cover scene would almost always have nothing directly to do with the contents of your magazine–right down to the characters depicted. If you were publishing ACTION COMICS, you’d just show some pulpy scene depicting action, maybe a guy parachuting out of a plane headed for a fiery crash, or a guy stalking or being stalked by a lion in the veldt. Nevermind what characters might be on the inside of the magazine–the cover in this earliest period was about selling a tone, a style, a sensibility.
