How does Mary Karr use imagery in The Liars' Club?

Although Karr often uses vulgar expressions that are part and parcel of the way many of the local people speak, she also on many occasions uses highly poetic imagery. This creates quite a contrast for the reader. In one of the milder examples of local slang, for example, a girl emerging from a coma after contracting encephalitis is "half-a-bubble off plumb." But on the next page, Karr uses a more literary form of expression, a simile, to describe the effect of her father's voice on the neighborhood children: "the kids all startled a little the way a herd of antelope on one of those African documentaries will lift their heads from the water hole at the first scent of a lion."