How do McCarthy's techniques convey the impact of the experience on the main character in The Crossing?

Cormac McCarthy uses a variety of techniques to convey the impact of Billy Parham's experience in The Crossing.  In the scenes when Billy kills the wolf and later carries her through the mountains to bury it, McCarthy employs vivid imagery to describe the scenes.  Billy is aware of every move the wolf makes, and these instances are detailed in imagery.

Further, McCarthy manipulates the syntax of the lines while Billy travels through the mountains.  At the beginning of the second part of the novel, the first paragraph is one single run-on sentence.  The speed of the line suggests the enormous impact that this experience has had on Billy.

This question is the basic premise of the prose rhetorical analysis prompt (Question #2) from the Advanced Placement English Literature and Composition Exam (1999).  The College Board compiles a variety of student sample essays after each test and posts them on their website to help students prepare for the exam.  View these essays for alternative perspectives on McCarthy's techniques.