Linear with Flashbacks, Colloquial
Let's talk first about the overall structure of the story. Georgie takes us from Agatha's funeral on June 7 through the end of October in 1871. However, she also has to tell us how a body everyone else believes to be Agatha's ends up in that coffin, and in order to do that, she flashes back to the winter and spring of 1871. But the flashbacks generally come in linear order, so we're not jumping around all over the place like Long Ears when he sees a cougar.
In terms of sentence-by-sentence writing style, we would say that Georgie is not a fancy talker. She peppers her speech with euphemistic swear words like "Dadgum mule" (8.1), and overall, seems almost like she's trying to sound less polished than she really is, which is perhaps part of her tomboy character. Her description of Mr. Olmstead's first courting of Agatha supports that idea. She says:
It was the kind of thing you might read in Godey's Lady's Book: "I wondered if you'd go for a stroll with me, Miss Burkhardt." "It would be my pleasure."
It was like that. I do not mind telling you that I did not care for hearing that sort of language in my own home. I nearly laughed out loud when Grandfather Bolte called the night "fine." It certainly was not! April rain had mucked up the road, and there was enough bite in the air to make your nose run. But out went Agatha and Mr. Olmstead into that "fine" evening. (7.32-33)
Nope, Georgie does not care for the pleasantries. She likes her language like her ammunition: shot straight out of the barrel.