Music festival

The audience received the bizarreness typical of Little Dragon’s performances with happy dancing — they bopped and bobbed perkily in time to the beat.

What became clear as the band launched into its closer “Breezeblocks” is the way in which alt-J has grown into its image.

But oddly, given the band’s reliance on heavy bass and a machine-gun drumline, there was no drummer or bassist to be found onstage, the two critical parts instead left on the shoulders of a backing track.

Every year since 2007, the Treasure Island Music Festival has set up shop on the man-made island of the same name between Oakland and San Francisco, offering two days of music, food and activities.