This big band disc from 1974 featured an ensemble of 15 players: three trumpets, two trombones, tuba, five reeds (including Rivers), two basses, and two drummers. The compositions have structure, but they’re also very open and give a lot of space for solos, which are bracketed by group fanfares in the manner of John Coltrane’s Ascension. One of the most fascinating aspects of it is its extremely wide sonic field — it was originally issued in a quadraphonic mix, and horns seem to come at you from all parts of the room.