One of the "purest" riff songs ever is Fleetwood Mac's "Tusk". Built around a repeating three note riff - -and two other short riffs. For me, this is about as primal as music gets. It does bounce around -guitar/bass/accordian/marching band - whatever's on hand, so I'm not sure it technically qualifies here. Still, this is great riff rock IMO.
Marty
Gasm, good to see Matthew Sweet get a shout out here.
Marty
Gasm, good to see Matthew Sweet get a shout out here.