Under These Rocks and Stones

In Under These Rocks and Stones, Canadian newcomer Chantal Kreviazuk comes across as an agreeable mediator between the angst-laden beltings of Alanis Morissette and the old-fashioned pop of Linda Ronstadt. She snarls like a smart woman scorned on ''Boot'' and coos like a post-Nyro balladeer on ''Imaginary Friend.'' Somehow, it all hangs together, in a friendly, just tough-enough package. B