How does Gjertrud Schnackenberg use imagery in Darwin in 1881?

In the conclusion, the poet ends the poem, Darwin in 1881, with imagery of the geological phenomena that became the basis of his scientific theory. Fossils found on ocean floors and cliffs, in ice, canyons, and so forth, support the idea of evolution, and at the end of his life, Darwin himself is like a "fabulous-headed / Fossil," ready to lie down for a final time.