Rich's poem is an extended meditation on the way moonlight reveals a landscape. The problem of the poem has to do with the word "amends"—what amends need to be made, and who needs to make them?
The poem is made up of a series of delicate images of objects illuminated by the moonlight. The moonlight is personified as a kind of force whose light brings these things into being; it "picks" at small stones, or "lays its cheek" on the sand. In another sense, however, the poet's vision is the controlling intelligence of the poem. There is a cinematic quality to the progression of things the moonlight sees, as if the poem was a kind of movie camera tracking across the landscape.
This progression of the camera/eye of the poet moving with the moonlight across the landscape reveals another kind of progression, from the natural to the manmade; the imagery moves from the surf to the tracks to the "gash" of the quarry, ending finally on the "eyelids of the sleepers" in their trailer, the adjective "tremulous" suggesting perhaps the movement of their closed eyes, as if they are dreaming.
The animating power of the moonlight "dwells" on these sleepers "as if to make amends"—a phrase that is extremely ambiguous. What does the moonlight need to make amends for, if not for making visible things that ordinarily would be left in the dark? And even this is conditional: it is "as if" the light is making amends. In other words, one might think the light was making amends, but that might not be the case.
It's possible that the moonlight's apparent gentleness is not gentle at all. It "flicks," "pours," "leans" and "soaks," these verbs suggesting a kind of unstoppable power. Perhaps it is the "sleepers" who need to make amends, or the poet, who, in presenting this vision, is asking for (or demanding?) a kind of forgiveness.