ac- cident-lack of cornice, dynamite grooves, burns and hatchet strokes, […]
We get more emphasis here on the "physical features" of the edifice-cliff that get a little more specific in the seventh stanza. And all the details sure sound very human-like and man-made, like a missing "cornice" (a fancy word for molding), "dynamite grooves," and "hatchet strokes." All of this damage would be made or caused by people, not the ocean, right?
Okay, so until the ocean starts learning how to use a hatchet, we can assume the speaker is focusing on human abuse. So now that cliff-edifice is getting beat up by both sides: nature (ocean) and man (dynamite). We guess that, as something that's both natural (cliff) and man-made (edifice) itself, that stands to reason.
But what did that cliff ever do to anyone? Well, the same could be said about any number of people who suffer abuse, especially during wartime. So it's not so much about why this is happening, but rather the focus is that it is happening, whether we like it or not.
You're probably wondering about the funny break up of the word "ac-/cident." The purpose here looks to be more about keeping with Moore's initial stanza pattern rather than some deep meaning. "Ac" rhymes with "lack," nice and simple, and keeps the rhyme scheme intact.
Notice too that this list of damage look a bit like that catalogue of sea creatures we saw earlier. The only difference is there's nothing peaceful and nice about these words. So yet again, Moore is establishing a sense of connection: life and death, earth and sea, resistance and damage, humanity and nature.
[…] these things stand out on it; the chasm-side is
What's more, there's no hiding all the marks of abuse on that edifice-cliff. They "stand out."
It's almost as if we can't even appreciate what beauty it might have had because of all of the damage. Notice we only get the perspective of the damage, rather than the parts that are still intact.
Fancy word alert: "chasm" is just a deep hole or cut of some sort. In this case, the chasm is caused by both nature and humanity.