On the subject of what type of magic site can be found in which types of terrain, I found an extra column I'd missed on the Excel spreadsheet complete list of sites which is at
http://www.freewebs.com/dominions2/, which gives the terrain the site can be found on. Which is very interesting. Actually I see the list was compiled by your good self, Edi, thanks for that.
Anyway, I can now see that there was little point casting Haruspex on mountain provinces, as there are precisely 0 Nature sites which only appear on mountains. Forests, swamps and water provinces appear to be the places to be. Which I guess kind of makes sense, but I hadn't realised there was _such_ a low chance of finding a Nature site in other provinces. I wasted a lot of turns doing that, but never mind, all part of the learning experience I guess.