On Saturday, September 9th, an impressive crew of musicians converged on the Mountain Theater in Marin County, CA’s Mount Tamalpais State Park for the 2018 edition of Sound Summit: A Benefit For The Mountain. This year, jazz-funk icon Herbie Hancock led an artist roster including Grace Potter, Nikki Lane, and Con Brio. In addition, the event saw Bob Weir reunite with his former RatDog rhythm section (drummer Jay Lane and bassist Robin Sylvester) as Bobby & The Chew Toys.With so much talent on deck for the evening, many fans held out hope for some onstage collaborations. Their prayers were answered during Herbie Hancock’s headlining set when Herbie emerged from behind his keyboards during “Chameleon” with his keytar in hand and some special news to announce:I’m gonna bring up a guest. A friend. Friendly face. Friendly sound. You’ve heard it, but every night…is different. Every tune…is different. Every time…is new. Here’s…Bob Weir!Weir joined in and augmented the already-grooving “Chameleon” improvisation, trading harmonic and rhythmic ideas with Hancock for the better part of ten minutes before the band brought the classic composition back home with its closing coda.You can watch full fan-shot footage of Bob Weir’s sit-in with Herbie Hancock below:Herbie Hancock w/ Bob Weir – “Chameleon”[Video: Steve Virshup]You can also view a partial video of the sit-in from a closer vantage point in the crowd here:Herbie Hancock w/ Bob Weir – “Chameleon” (partial)[Video: Dr. Randy’s channel]Sound Summit is building a reputation as a breeding ground for incredible collaborations. Last year, Weir sat in with Jim James at the event. Later in the evening, both Weir and James joined in with Phil Lesh & Friends. We can’t wait to see what magic iSound Summit cooks up for next year.Sound Summit is presented by Roots & Branches Conservancy, a group dedicated to raising funds for natural resource protection and conservation of Mount Tamalpais State Park and the surrounding areas. For more information or to find out how to donate, head to the group’s website.