I've been trying to look online for a word for this. What I mean is, for example, say a composition begins with drums, then some other instrument gets added (say, violin), then another, then yet another.
So, say, the main theme of 3:10 to Yuma (2007). The closest I could get on the web was "intensify" or "heighten" but that's not what I think accurately describes it. In fact, even the use of the word 'layered' in the question might be entirely wrong. Any help is appreciated. Thank you.