I'm reading a book and it's showing different examples of modulation or changing keys. At the bottom of the diagram where it shows some sheet music is a little chord thing that I'm having trouble figuring out. Here's what it is:

[CI (=GIV), GII*), GV6/4, GV, | GI]

Here's a picture of it so you can see:

http://img841.imageshack.us/img841/8784/modpic.jpg

Also I think at the bottom it's saying that whenever you see a chord with an underline II that it means 1st inversion. However, underneath that it says that when you see a double-underlined chord it's the 2nd inversion. That's funny because there isn't a single chord in the entire book that has a double-underlined chord, and the only thing resembling that that I see on this page is the = sign, and I was thinking that means equals.

I think that when it says GIV, it means that C is the 4th chord in G. I don't understand the GII thing at all, even though I think the underline part means 1st inversion. GV6/4 seems to be the 2nd inversion of the 5th chord in C, but there aren't those two lines as mentioned, only 6/4. Maybe the book made a typo? I also understand GV to be the 5th chord in C, and GI to be the new tonic. I think...

But I don't really understand the sequence of them either. GIV, GII, GV6/4, GV, then GI. Not sure what this entire mess is about but I hope someone can help me decipher it.
I've never seen that formatting style for roman numeral analysis, but CI (=GIV)is telling you that the I chord in C is equivalent to the IV chord in G. The underlined II with an asterisk is an alternate analysis of the chord, taking the A on beat to as a chord tone as opposed to the G on beat 1. This type of re-interpretation of a chord from old key to new key is called a pivot chord modulation.

The letter before each roman numeral is just a reference to the key I think...

The GV6/4 is actually still an extension of the dominant that it precedes. You could re-write beats 3 and 4 as simply V6-5/4-3, as in the 6th scale degree (in G) moves down to the 5th scale degree and the 4th moves down to the 3rd.

One reason you aren't seeing 2nd inversion chords is that they can often be explained as something else, and therefore aren't truly function 2nd inversion chords. They are usually a result of suspensions or passing motion.

Hard to hit all the points in your post, but hope this helped some.
I wasn't really putting together both the bass and treble clef, but now I see what's going on. The chords on beats 1-3 match up with what's going on in the little chord list below, except for the chord that's on beat 4. There's an A in the bass clef, and an F# in the treble clef. For the 4th chord in the chord list, it says GV. Well if G were the V chord (in C), there definitely wouldn't be an A in it, and definitely not an F#.

That leads me to believe that when it says GV there, it's talking about the 5th chord in -G-, which is a D Major chord, and that does have an A and an F# in it (and a tied D as you can see). It's just confusing since it's not telling you exactly which key it's taking the chords from for every chord listed, but I got it figured out now I think:

CI (key of C), GII (key of G), GV6/4 (key of C), GV (key of G), then of course, GI (key of G). I wish it would note that for you.

Only thing I can't figure out is where it says "=", like a double underlined chord is supposed to be somewhere but it isn't, I only see 6/4. Maybe there was a typo and they meant to put 6/4 at the bottom instead of =, because that would make sense.
Last edited by thared33 at Mar 26, 2011,
In the first example, in the key of C you have chord I, you then go to a second inversion G chord (Vc) which usually would resolve to a first inversion C chord (Ib). Instead, it is treated as a cadential 6/4 in G major and the soprano and tenor line fall by step to a D major chord, the V of G.

The second example, you basically have a C major chord followed by a iib Ic V I progression in D.

Both of these are examples of Pivot chords , which use chords common to both keys to lead to a modulation.
Last edited by griffRG7321 at Mar 26, 2011,