Sons of Mercury (1968-1975) (1991)

The musical chasm separating San Francisco and Los Angeles was never more evident than in the late '60s. The Bay Area became world headquarters for acid rock, as groups like Quicksilver Messenger Service worked their blues and folk roots into elongated soundtracks meant to reflect and accompany psychedelic experiences. The two-CD Sons of Mercurychronicles Quicksilver's unique development from searing guitar solos to refined piano work, in a career marked by tautly focused improvisations. While many of Quicksilver's peers wrapped their music in the mystique of the drug culture, Sons of Mercury has an appealingly alert, aboveground sound best heard in such sturdy singles as ''Pride of Man'' and ''Fresh Air.'' B