Okay okay. In case
Urwen's is
not correct, I got one more idea - prompted by
Gal's advice regarding the problematic verses.
At least this:
Are they coming? No more going.
You can't watch the water flowing!
If the only reason I can't watch the water flowing is that it is still, then... that brings to my mind the dammed Sirannon by the gates of Moria (with the lovely Watcher and all that belongs to it). The sentence
are they coming? would then be much more literal reference to the famous last words in the Book of Mazarbul. (And why there can't be any more going when they are coming, is obvious: the Western side is blocked by the non-flowing water, the Orcs are coming, nowhere to go.)
Now it would be the rest of the riddle, on the other hand, which would prove more tricky to decipher. Of course many of the things can be taken as a general referrence to e.g. Moria as a whole. What puzzles me is
Galadriel's insisting on the past/present explanation of the two parts of the riddle. Because to me, I have been taking note of this, but it does not seem to be such a big deal. Unless...
Unless it's the Book of Mazarbul itself (and I should facepalm myself for writing two paraghraphs of thinking aloud since mentioning it the first time). Then the "taking" and all (taking the book to carry it along, certainly not being a "happy" read; nor is it any beauty - it's been pretty much damaged in the battle, pages torn, bloodied, "skin" - possibly even the literal leather in which it's bound, huh? - also damaged...) would be very much plausible. Ah yes. That might be it. And, of course, what else does a book like that do than to
list events - then, the past/present division would really be important in the riddle...
So? Is it the Book of Mazarbul?
