Every so often, a band comes along that by all rights should be awful but turns out to be awesome. Arbouretum is a Baltimore quartet that plays a brand of melodic, progressive hard rock with sludgy riffing, stately vocals, overdriven bass and extensive but somehow nonindulgent soloing. It gets better/worse: According to Arbouretum's bio, its fourth album, "The Gathering," "was to a large extent inspired by 'The Red Book' by Carl Jung, or more specifically, Jung's pursuit of the inner images that led to the book's writing." In other words, this album sounds like it was recorded in 1972 and should be packaged in a heavy gatefold sleeve with a big photo of the longhaired band standing in some bucolic woodland setting. For sure, Sabbath, Zeppelin and more obscure bands of the era like Wishbone Ash loom large over the proceedings, but Arbouretum breathes new life into a long-dormant genre with its melodic flair, the freshness of its approach and the tastefulness of its playing-and to call a band whose average song length is six to seven minutes "tasteful" is no faint praise.