Narnia discussion

It is the name for all the land under the fictional world of Narnia. The top is called the Marches, the Deep Realm is much further underground, and Bism is another six thousand feet below them. Underland is inhabited by the Earthmen who are from Bism, a land of molten rocks. They call the Marches and the Deep Realm the "Shallow Lands". All outlets from Underland to the Overworld lie across the Sunless Sea (except for the tunnel dug by the Earthmen under the spell of the Lady of the Green Kirtle).This is again in the Silver Chair.