In this passage, the author uses personification. Personification occurs when an author gives human qualities to animals, objects, forces of nature, or any other element that is not human. The author of this passage presents the mountains in a way that resembles humans, as he tells us that they stood shoulder to shoulder and that they glared down at the pastures and dared anyone to come. The effect of these words is to provide a vivid image of how intimidating the mountains were and how powerful they seemed to others.