What is the importance of White Sulphur Springs in the memoir, This House of Sky: Landscapes of a Western Mind?

White Sulphur Springs was the name of a major area within the state of Montana where the author's father and grandmother spent a great deal of time working. It is in Montana and is named in an incredibly straightforward manner.

There are white sulphur springs in the area which serve to give it a definitive quality to people who travel through or live in the region. This sets it apart from other areas within Montana which have been given other names to prevent confusion.