I never did dissect a frog in school. I remember feeling decidedly squeamish about poking about inside something that is better off appreciated as a whole. The same might well be said of terroir: at best it is a slippery subject to pin down (much like a frog), and can be easier to understand in general terms than under close scrutiny.
Because the concepts that make up terroir are so varied (soil, weather, topography and so on) and the results so extremely subjective (taste), the risk of dissecting terroir is that the deeper you probe, the more confusing it becomes...