In the late '60s, both the Groundhogs and Peter Green's Fleetwood Mac emerged from the U.K.'s blues revival. Not only were these the scene's two best groups, they were its most adventurous. Split, from 1971, is a song cycle about schizophrenia. The theme is driven home by the trio's manic jams. Sure, this is blues rock, but it's a long way from home. The Groundhogs snarl with jagged teeth; they don't ride grooves so much as utterly obliterate them. The wailing feedback of "Junkman" will melt your face.