Final answer:
The imagery used in 'It Sifts from Leaden Sieves' with 'Alabaster Wool' creates an image of the snow as soft, fluffy, and transformative, covering the road in a gentle and serene manner similar to a soft blanket.
Step-by-step explanation:
The imagery in the excerpt from "It Sifts from Leaden Sieves" that describes "It fills with Alabaster Wool The Wrinkles of the Road" serves to beautifully convey the gentleness and softness with which snow covers and transforms the landscape. The use of the word 'Alabaster' suggests a smooth, soft and white substance, much like wool, which gives texture to the otherwise hard surface of the road. Therefore, this imagery is not about the heaviness or the speed of the snowfall but rather involves a comparison with wool to highlight the softness and calmness of the scene, much like the gentle laying of a blanket.