The Grateful Dead’s Jerry Garcia was known for his affection for bluegrass, which led him to form side bands like Old & in the Way, but his reputation as an acid rock guitarist always stood in the way of wide acceptance in the bluegrass community. The Yonder Mountain String Band, representing a new generation of bluegrass pickers, not only seems ready to admit Garcia to the bluegrass pantheon, but also wants to adapt the Dead’s taste for meandering improvisation to what was previously a form of music devoted to speed and economy. The group is thus evolving a new form of bluegrass that has earned it kudos in the jam band category, and this tendency is nowhere more evident than in their two live albums. This second one, recorded in the fall of 2001, gives a good sense of the band’s proclivities and talents. They’re not afraid to take off on extended excursions, stretching a medley of mandolinist Jeff Austin’s “Peace of Mind” and “Follow Me Down to the Riverside” past 26 minutes, and their choice of covers is revealing. The Rolling Stones’ faux country “No Expectations” is played for real and extended to ten minutes; outlaws Waylon Jennings and Willie Nelson are recalled on “Good Hearted Woman”; and John Hartford’s “Two Hits and the Joint Turned Brown” reeks of reggae and ganja. The Yonder Mountain String Band is becoming to bluegrass what the Kronos Quartet is to chamber music; just as that classical outfit shakes things up by performing Jimi Hendrix’s “Purple Haze” as an encore, so this bluegrass group does the unexpected by gathering around a single microphone on the album’s hidden track, a soulful rendition of Pink Floyd’s “Goodbye Blue Sky.” Bill Monroe may be spinning in his grave, but the audience has a great time. – William Ruhlmann