Much pop/rock music draws not (only) on the classical major/minor system, but also on diatonic modes. These are not the modes as used in the Medieval Christian church, but the diatonic modes common in Western (especially English and Celtic) folk music.

The most common modes used in this “tonal system” of pop/rock music are:

• Dorian: do re me fa sol la te do
• Mixolydian: do re mi fa sol la te do
• Aeolian: do re me fa sol le te do

(Lydian is also possible, but rare. Locrian is rarer still, given its lowered fifth scale-degree. Phrygian is common, but typically as part of Everett’s “System 5.”)

The characteristic harmonies in modal pop/rock include a heavy emphasis on flat-VII as the primary “dominant” chord (rather than V or even v), as these four common modes all contain te. Flat-VI is also common in Aeolian, and Flat-III in Dorian and Aeolian.

An obvious example would be “Scarborough Fair,” by Simon & Garfunkel. This is based on a Dorian folk melody, and the harmony reflects this folk origin, emphasizing i, III, and flat-VII.

This harmonic language can be found in Simon & Garfunkel’s original compositions, as well, such as their Aeolian-based song, “The Sound of Silence.”

Irish band U2 uses modally based tonality frequently. For example, the intro and verse of “In God’s Country” is built on an alternation of I and v (Mixolydian). The chorus modulates up a step, switching to Aeolian/Dorian (there is no la or le present to distinguish between the two).

“Sunday, Bloody Sunday” is another prime Aeolian-based example from U2, with harmony built on i, III, and flat-VI. (Note the occasional tag in the parallel major, built on the “double-plagal” progression, flat-VII IV I.)