Violin and viola improviser Mary Oliver is the newest member of the ICP and, like Michael Moore, she's another California expat, living in Amsterdam since the late '90s. She showcases her extemporaneous playing on her solo album Witchfiddle (ICP), which is comprised of 11 bracing instant works. Oliver has a dual background, premiering works by important contemporary composers like Iannis Xenakis and John Cage, and playing side by side with top-flight improvisers like Evan Parker, Tristan Honsinger and Joelle Leandre. The varied experiences come through in her music. The music on Witchfiddle reflects the extended technique required by much contemporary composition-precise thwacks, snaps and taps, and unison vocal effects among them-but there's an unpredictable flow of ideas that's straight out of the free-improv tradition. It's heady, challenging stuff, but Oliver maintains a certain lightness and dexterity; even at its most abstract the music sometimes appears to float away. She reveals a stunning range of color, her brittle scrapes suggesting fingernails dragged across slate and her arco sawing drawing images of huge, billowing puffs of gray smoke. She also included a superb improvisation on Scandinavian Hardanger fiddle, a deeply resonant cousin to her main axes.