There are many different poetic devices used in Seamus Heaney's poem, "Bogland." First, there is allusion, for example, in the reference to the Cyclops' eye. Although the poem does not have a regular pattern of rhyme or meter, the four line stanza creates the figure of parallelism and, at certain places, isocolon. There are several places in the poem where Heaney uses alliteration (sights/sun, melting/missing/millions). Heaney uses simile in several places (soft as pulp) and metaphor (e.g. bottomless, black butter). He also uses praeteritio, e.g. in his description of not digging coal. he also uses climax in the way he invokes increasingly important images.
The main themes are the contrast between bog and prarie and the notion of the layering of history in the bogs.