A "rock blues" in a major key uses dominant seventh chords at up to 120 beats-per-minute. The harmony stays on the I-chord for bars one through four, then in bars five and six switches to the IV-chord, before going back for two more bars of I-chords in bars seven and eight. Then it descends from a V7-chord in bar nine, to a bar of IV-chord in bar ten, to a I-chord in bars eleven and twelve.
