The speaker walks through a wooded hollow and records what he sees in short, separate glimpses. A hemlock is almost dead from adelgids, the insects that attack these trees. Its branches are bare, "unfeathered," a nice word that makes the tree sound like a stripped bird. Then come quiet signs of change: more rain every year, train noise sinking into the ferns, and an ice avalanche that seems to stick in memory.
The poem then turns personal. A mark a brother once left on a tree has vanished under moss, so the natural world is slowly covering over a human trace. The last image is the strangest: two faces on a beech, one without a mouth. Judging by the imagery, the poem suggests silence, absence, and things that can no longer speak.
The mood is watchful and elegiac. The speaker never complains outright. The gaps between the lines leave room for quiet grief about a landscape, and perhaps a family, slipping away.