Originally Posted by: MglamboI determined that it resolved to D just by ear - playing a D note as it landed on that chord at the end of a verse.[/quote]

Got it. Good thinking!

[quote=Mglambo]The song is by The Grateful Dead.

Thanks!

That's definitely a modal tune in mostly D mixolydian.

D (I) - C (bVII) - G (IV)

There's a little guitar motif that is played occasionally that outlines:

d-c-d, c-b-c, b-a-d-b-a-d

That's clearly referencing D mixolydian. There are times when other guitars & the bass use D pentatonic minor with the note F. And that's a way to add a sort of a bluesy element.

Also, there is an F major in the "turnaround" or "chorus"

F (bIII) - C (bVII) - Em (ii) - D (I)

The F is a modulation. You'd have to adjust the mixolydian mode to dorian briefly to stay strictly with the chord changes. But 2 things are important to keep in mind here.

1. That F happens very quickly compared to the other chords. And it's a bluesy element you can add at will.

2. This is the Dead & they are a very loose, free-form jam band. Especially in this tune, they weren't as concerned with staying precisely within the key or chords. There are place in which you can hear several instruments colliding with different modes & licks.

Another important point about this kind of playing. It's not as if they are constantly using every note from any given mode. Just a touch of D mixolydian here. A touch of pentatonic major here & minor there.

Have fun with it!