Then your warm hands hummed over and shoveled themselves full of the ice and the snow. I would darken and spill all night running, until at last morning broke the cold earth and I carried you home, a river shaking in the sun.
Whereas the majority of the poem to this point has been end-stopped, the enjambment in this last stanza creates a sense of breathless urgency before culminating in the final image of the "river shaking in the sun." With the exception of the penultimate (or second to last) line this entire stanza is enjambed.
Here we have a powerful metaphoras our final image, this image of a river in the sun. What could this metaphor symbolize? Perhaps the river was once frozen, and is now thawed, exposed to the warmth of the sun.
Could this refer back to the version of the Windigo story Erdrich shares in the introduction, ending in the vanquishing of the Windigo? The image, ultimately, is ambiguous. We're not sure whether to be somewhat hopeful for the abducted child, or just totally skeeved out.