It struck me, while I was reading it, how much influence the modernist movement has had - much more than we probably realise day-to-day. At one point, when they first hear the sounds of approaching Indians, the two women are described thus:
Cora set the example of compliance, with a steadiness that taught the more timid Alice the necessity of obedience.
It's hard to imagine a more bloodless way of describing two young women trying to remain composed in the presence of looming danger. But that's to our modern ears. We're used to getting into the heads of characters, even in omniscient narration, and even if sensationalism is not being called for.
And partly, perhaps, this is because we have become so used to the Uncle Charles principle in fiction, in which we're taken into the head and thoughts of the character through the omniscient narration adopting the tone and mood of the character in question. In the original Uncle Charles example, from Joyce's Portrait of the Artist as a Young Man, we are told that Uncle Charles "repaired" to the outhouse. The pompous and overblown verb "repair" gives a sense of the character and so we view what's happening partly from his point of view.
In Cooper's prose, that cannot happen. We are told absolutely from the outside, from the objective view of someone who wasn't there. That feels almost alien in today's literature, where we would expect, without falling into didacticism or sensationalism, to nonetheless be given an impression of the reaction of the characters.
The flatness of the style takes some getting into.