How to describe this kind of harmony

[AngelCityOutlaw]

Okay, so I never thought about it until recently really:

I notice that it is most common in rock and metal music; there isn't really a simple sequence of chords, instead most would call it "riffs" right? Well, you can usually still find a way that you could break it down into a simple sequence because of chord tones within that phrase. In metal music, it's often done by changing up the pedal tone on the lower strings.

http://youtu.be/yRXk98QtjWA?t=2m22s

Consider the solo section there in that link at 2:22. This is what I'm talking about, it's not a simple sequence of chords, in fact it's only fifths, but you can still hear the rise and fall as if it were.

I always thought I understood the concept and I've done similar things in my own music, but I don't really know what it is called. It's more like an implication of chord progression is it not? Is it similar to when you do have a simpler sequence of chords and the bass plays various different chord tones and non-chord tones? What is all the theory behind that? Is there more I can read up about it?

Here's another example:

[DarkeSword]

There are still chords. The chord progressions are just very simple and spread out over a lot of measures.

A riff doesn't replace a chord. A riff is just a small chunk of melodic line. There is still a chord progression, even if all of the notes in the chord are not necessarily represented in the bass or accompaniment or whatever.

You're jumbling up a lot of different things here but there's nothing special about it. It's just really simple chord progressions.

[AngelCityOutlaw]

I thought I was probably just over-thinking things.

Thanks for the help!