Tell us where you saw it--what's the title of the book--and give us a few sentences before and after it. My suspicion is that this could well be the result of OCR (optical character recognition) errors on text that was scanned into a computer as an image. Either that or it is some kind of weird stream-of-consciousness nonsense. "Craggie" with an "i" could be a Scottish surname. "Craggle" with an "l" is neither a word nor a common surname. "Stalk" is a word, it is the tough vertical part of a plant, but "steep stalk" doesn't make sense.

In this case the stalk would mean like a place where there's is a spooky looking tree without any leafs while for Craggle I believe that is their names.