What is the author's style in The Diamond Mine by Willa Cather?

"The Diamond Mine" is a little confusing, because it does not follow a straight chronological pattern. The story starts out on a ship, when the narrator notes, "I first became aware that Cressida Garnet was on board when I saw young men with cameras going up to the boat deck." This opening immediately gives the setting of the story, or so the reader believes. But after the first paragraph, the narrator jumps back to "a few days before, when I was lunching with some friends at Sherry's." The narrator refers to this lunch so that she can get the "diamond mine" reference in there that she has overheard, but then she wanders in her thoughts about Jerome Brown.