Lines 10-16 Summary

Lines 10-12

Soon the sun's warmth makes them shed crystal shells
Shattering and avalanching on the snow crust—
Such heaps of broken glass to sweep away

• When the sun gets hotter during the day, the ice covering the trees starts to melt.
• It doesn't just melt like snow though. The ice is "cracked and crazed," so when it starts to melt, the bits of ice between those cracks break and fall off the trees.
• The speaker is using dramatic language to get you into the feeling of experience. He compares the breaking ice to shattering crystal and glass that falls like an avalanche.
• The snow is crusty, because the sun has melted the top layer of snow the day before and the cold night made it freeze hard again.
• The shattered ice collects below the tree as if it were a pile of glass being swept into a dustpan.

Line 13

You'd think the inner dome of heaven had fallen.

• There are a couple of important things going on in this line.
• "Dome" calls up a number of interesting connotations.
• Early Judeo-Christian thinkers believed that the sky was a dome that separated heaven and earth.
• The idea of a dome also brings to mind the ceilings of some cathedrals and churches.
• Emily Dickinson took this idea and combined it with nature. In her poem "Some keep the Sabbath going to church," she writes how Nature is her church and she has exchanged an "Orchard, for a Dome."
• This falling dome business is another allusion. This time we can trace it to Samuel Taylor Coleridge's "Kubla Khan." Check out lines 45-49:
  
  That with music loud and long,
  I would build that dome in air,
  That sunny dome! those caves of ice!
  And all who heard should see them there,
  And all should cry, Beware! Beware!
  
  The emperor Kubla Khan had this icy, heavenly pleasure-dome built. Like all good things, however, it didn't last.
• By connecting "Birches" to "Kubla Khan," we might expect "Birches" to be a bittersweet poem, perhaps about other things that don't last.

Lines 14-16

They are dragged to the withered bracken by the load,
And they seem not to break; though once they are bowed
So low for long, they never right themselves:

• The trees are bent down under the weight of ice and snow until they reach the shrubs and ferns (a.k.a. "bracken") on the ground below.
• To the speaker, the birches don't crack or craze like the ice. They bend, rather than break.
• However, the word "seem" should tip you off that this might not be the case.
• When the trees are bent down for the entirety of a New England winter, they don't straighten out afterwards. So, in a sense, they're broken.