Quarries are big holes dug in the ground. Its rare theres any "Transition" at all, except the line where the Machine Made Hole in the Ground stops, and the vegetation starts again. Usually this is further dilineated with a fence to keep trespassers out, but not always, depends on how close the hole is to civilization and how active the digging is.
After that, for Green Textures, I can only suggest to follow Mjolnir's advice. I will add though, that just like Object assets, Textures really just take some time to get to know them. Find a spot on your route you don't care about (Or make a spot, add 2-3 Baseboards in a straight line away from the RoW and use the last as a Pallete) and just go looking through your Textures. Check ones with names that sound like what you're looking for. Check ones that have a thumb that looks like what you're looking for.... Check them randomly.... Doesn't really matter how you do it, just start tossing Paint until you find one you like. Just don't forget the Ctrl Z key to undo.
Finally, something I found that helps alot, is find the Veggies you want to use first (If you're going to use 2/3D veggies), and plop some of those down so that you can get an idea for which texture might match your veggies.
Falcus