What Lawrence does, really, is employ geography as a metaphor for the psyche—when his characters go south, they are really digging deep into their subconscious, delving into that region of darkest fears and desires.
Lawrence's physical journey---moving from one place to another, a change in geography---also represented his mental, emotional journey of facing his fears and wants. The change in location, both concretely and tangibly is definitely a cool metaphor a skilled author would employ.
