I'm sorry, but an "alternative" station that regards Jimi Hendrix, The Who, Pink Floyd, The Beatles, The Rolling Stones, or Steely Dan as "core alternative" ain't an alternative station. Black Crowes, Bob Marley and Earth Wind & Fire aren't "core alternative" either.
Did those bands influence alternative acts? Surely. Have they got songs that fit in an alternative format? Absolutely. But "core alternative"? Nuh-uh.
Alternative begins with The Ramones, Television, Richard Hell, Jim Carroll, Blondie, Talking Heads and the NYC scene in 1975-76.
The Ramones ignited The Sex Pistols (and Siouxsie, their most prominent fan), The Clash and Generation X in London and the London punk explosion, which ignited Manchester punk/post-punk explosion (and in doing so transformed a lot of glam and pub rockers into punk/new wave acts, like The Damned.)
Before that, it was all "rock".
Meanwhile, Bob Marley was only the most prominent example of island influence, which included Desmond Dekker & The Aces, Toots & The Maytals, and never forget Millie Small, all informing the Two-Tone movement (and giving Eric Clapton a hit record, of course.)
Precursors include The Stooges, The Velvet Underground/Lou Reed, The Doors, The Modern Lovers, The Kinks, The Animals, pub rockers like Graham Parker, Rockpile and Bruce Springsteen (a Patti Smith collaborator, among many other things), glam rockers like Roxy Music, Brian Eno and The New York Dolls...
...not to mention what was happening in (West) Germany with Can, Neu and Kraftwerk.
And don't underestimate the role of BBC Radio, John Peel especially, and Tony Wilson on ITV in granting all aspects of the underground a nationwide UK audience, and informing the import scene that drove alternative back here in the states through college radio record pools like Rockpool.
I haven't even started on the DC, Athens GA, LA, Chicago, Minneapolis or SF scenes...
I'm singling out Black Crowes for exclusion especially, though. They're a blues/roots informed rock band, and there's nothing alternative about 'em. And don't go telling me "but alternative stations played them, therefore they're alternative", because alternative stations played Wham! too...