Snow Angels Library Edition

"Milliken and Mae Mae have never left The Trench--it's all they've ever known. ... The two girls, eight and eleven, are a part of the Trenchfolk, a sprawling settlement of people living inside the massive ice walls of a vast, seemingly endless frozen trench carved into the surface of an otherwise icy wasteland. ... On Milliken's twelfth birthday, their father takes the two girls on an overnight skate down the trench--a coming-of-age ritual to teach them how to fish the frozen river, how to hunt the wild Trenchdogs that wander its frigid banks, and how to give proper thanks to their frozen Gods--the Colden Ones. It's the trip of a lifetime until the girls push beyond the borders of their humble land and awaken the Trench's deadly defender"--