Emerging in the wake of Miles Davis’ initial experiments in fusion, jazz rock has spawned so many divergent artists that it’s nigh impossible to wrap the movement in a single, tidy package. On the one hand, there’s Joni Mitchell and Steely Dan, both of whom craft songs that, while deeply idiosyncratic, possess enough hooks for radio airplay. But there are also bands like early Chicago and Mahavishnu Orchestra whose jams explode with mind-expanding solos. Though jazz rock peaked commercially in the ’70s, the later arrival of Medeski, Martin & Wood and Morphine continued the movement’s wonderfully unique sounds.