How does the author use imagery in the story, The Moorchild?

The author uses detailed imagery to describe the cavernous Mound that glitters with a greenish light, its walls and ceilings studded with jewels to the eyes of a human. In the Gathering, the tables are laden with pheasant and fruits and elegant wines, while the wild dance goes on and the Folk, their pale hair fluttering, float up and down the winding golden stair in careless play and abandon.