I can't post pictures right now, but you know the kind of cover I mean - one where the characters are talking about what's happening ("We'll all be crushed!"). In most of its covers in the 1960s, Marvel avoided that kind of cover and had a silent drawing depicting what happened in the book, plus some text hyping the story or just giving the title.
That changed around 1970, I think, when most of Marvel's covers switched to having dialogue on them. And that continued to be the case for most Marvel covers until Jim Shooter took over as editor-in-chief; after that, dialogue covers were mostly phased out.
Does anyone know why Marvel changed its policy on cover dialogue around 1970? I think, in general, it made the covers less interesting and special; covers from that era are sometimes good but they have a factory feel about them - partly due to the art department designing most of them (the artist usually wasn't allowed to come up with his own ideas for the cover) but partly due to all that dialogue. I'm glad Shooter went back to the silent cover with text, which works better for me.