What is the author's style in Prodigal Summer: A Novel by Barbara Kingsolver?

The author extensively uses the language and dialect of those who live in this part of the Appalachian mountains. To assist the reader in recognizing this specific dialect, she puts words in italics and mentions how the character's phrasing would compare to "regular" English. She also uses language to enhance the differences between Eddie Bondo, from Wyoming, and Lusa Landowski, from Lexington.