The Watchers — Jane Louise Curry

At war with his stepmother, in trouble at school, and desperately unhappy, thirteen-year-old Ray finds himself shipped off to distant family in the high mountain hollows of Western Virginia. There Ray encounters a strange world of mystery, where nothing quite makes sense. The mystery deepens when he discovers a great stone snake carved on the wall of an old coal mine high in the hollow. A piece of that stone draws Ray into a conflict that echoes an ancient tragedy played out over sixteen hundred years before.