The author is Molly Gloss. Her best book, IMHO, is The Jump-off Creek. Inspired by the life of the author's grandmother, it tells of a woman setting up a homestead, solo, in western Oregon. It's short and terse, with not much plot line, but really gives you a feel for what it was like.
The Hearts of Horses deals with a young woman who, during WWI, when able-bodied men are scarce, gets a job in a small Oregon town breaking horses. She has a good feel for what horses need, and how to handle them. It's a really good job of capturing the feel of the time.
Gloss also wrote a well-regarded science fiction novel The Dazzle of Day--a colonizing a new world story.