Hello! I need a little help understanding this line in the poem Spring And Fall, by Gerard Manley Hopkins. I will share the full poem first. to a young child

Margaret, are you grieving
Over Goldengrove unleaving?
Leaves like the things of man, you
With your fresh thoughts care for, can you?
Ah! as the heart grows older
It will come to such sights colder
By and by, nor spare a sigh
Though worlds of wanwood leafmeal lie;
And yet you will weep and know why.
Now no matter, child, the name:
Sorrow’s springs are the same.
Nor mouth had, no nor mind, expressed
What heart heard of, ghost guessed:
It is the blight man was born for,
It is Margaret you mourn for.

Got it? So, the line I am struggling with is "Though worlds of wanwood leafmeal lie". Based on the meaning of the poem I think this line is supposed to mean extrodinary things. Would you agree? And if not, can you explain to me what it means?