The southern wall of Westfold was formed by the White Mountains, and in a part of that range was a broad vale, several miles across: the Westfold Vale. On the western side of this bight, a narrower valley led on into the Mountains. This was the Deeping-coomb, the entrance to Helm's Deep where the Rohirrim sought shelter when Dunlendings overran their land. Centuries later, the armies of Saruman marched through the Vale and into the Deeping-coomb, only to be defeated at the Battle of the Hornburg.

Earlier editions of The Two Towers contain a slight but significant error regarding the Westfold Vale. Whereas Tolkien's original manuscript makes it clear that the Vale was itself a 'great bay in the mountains', the text was garbled in reproduction, so that the 'great bay' appeared to be a reference to the Deeping-coomb, rather than the entire Vale. This confusion has been corrected in later editions of the book.