The first stanza of "Roe-Deer" works like a stage curtain rising to reveal a mysterious scene. Take a look at the anaphora in the first line:
In the dawn-dirty light, in the biggest snow of the year
That repeated "in the" creates anticipation: what is it that the speaker will see "in the" early light and the snow? The second line reveals all:
Two blue-dark deer stood in the road, alerted.
The imagery of those "blue-dark" deer in "dawn-dirty light" draws readers right into the scene: this is the early, early morning, with heavy snow-clouds letting only dim, shadowless light through. The speaker, presumably out for a walk (or perhaps a drive), has come across two deer in the middle of the road. The single word "alerted" paints a vivid picture of the deer's turned heads and pricked ears, suddenly aware of the speaker's presence. And all on their own, these sights also conjure sounds—or the lack of them: the muffled quiet of a snowy dawn.
The speaker's encounter with those two deer in this silent landscape already feels more like a first contact with aliens than a picturesque moment in the countryside. These deer, the speaker goes on in the second stanza, seem as if they've come from another "dimension" at exactly "the moment I was arriving just there," a phrasing that insists on how unexpected and fortuitous this meeting feels. If the speaker or the deer had turned up just a few seconds later, their "dimensions" couldn't have overlapped this way. Through this chance meeting, the speaker will catch a glimpse of a whole different world.
This free verse poem's shape will mirror the speaker's vision of nature's strangeness. Readers may already have noticed that most of the stanzas here are unrhymed couplets: they arrive two by two, like the two deer themselves. (One notable exception will appear later on—keep an eye out!)
And while the poem doesn't use rhyme, it does use intense patterns of sound to create music and atmosphere. Listen again to those first two lines:
In the dawn-dirty light, in the biggest snow of the year
Two blue-dark deer stood in the road, alerted.
Here, /d/ and /b/ alliteration sounds like muffled footsteps in snow; /oh/ and /oo/ assonance evokes a faint winter wind, the only sound in a silent world.