The art of making mountains

The “shattered” doesn’t seem to fit. “Crumbled” perhaps, but the connotation of shattering is noise, violence, obviousness; and these don't fit with “before we realized”, which connotes something sneaking up, growing unobtrusively.
The rest of the write works well, and I especially like the last 2 strophes. They are full of good images, they are simple and direct, yet effective. One small error: I think that “heldfast” should be two words.
Alcuin