Oh, joy, a rationalist's adventure novel. (Two novels, originally; The Steerswoman and The Outskirter's Secret.) It has paladin researchers, and a great deal of ecology, and a central friendship, and a fundamentally anti-aristocratic political stance, and a tragedy that doesn't turn out better than it ought to. The heroines are good at things because they've spent years, decades, practicing them with the best people they can find, not because they were chosen by fate. There are goats, doing what goats do best. All my buttons neatly pushed.
The world has a small and seemingly beleaguered human settlement, with barbarian outlands and troublesome wizards; the main character belongs to a very open college of mapmakers and inquirers who travel all the time to find out and share information. She gets hold of a thread that turns out to be a World-Shattering Plot.
She might be too smart to be realistic, though Kirstein does a pretty good job of tracing out leaps of plausible inference. Kirstein doesn't try the bravura trick of writing that mental experience from the inside, although she does describe the elation of having it.
This is the novel I wish Forge of Heaven had been, in that the whole problem isn't explained at the beginning, and the central characters are interesting ones. There's still a central villain to be met, too; there are two more novels in the series. Oh, joy.
Find in a Library
So wrote clew in SF&F.