Letters I've Written, Never Meaning to Send

So I'm sitting here in a coffee shop trying to get some writing done. Or more accurately, I'm really just trying to plan some writing, and even that's not happening. See, the work I've been doing for the past while has to do a few different things. I might end up turning some of it into a job talk, and part of it'll certainly be its own essay at some point. But right now, I'm getting set to write this stuff up as a chapter of my dissertation.

The problem is, it's the chapter that's really nothing but a random salad of background material for later chapters. I can't leave parts out just because they don't fit into any nice, compelling narrative thread that could tie the chapter together. It's all got to be in there to set up the next two chapters.

So here's where I'm stuck. How do I transition from one part of the chapter to a completely unrelated part of the chapter? "Meanwhile, back in the Fortress of Solitude. . . ." Or maybe I should just make the key section heading, "Segue!" I'm getting desperate here. Seriously.