It’s been 12 years since Gurganus last published a full-length work — but if there remains any doubt of his literary greatness, his fifth book, “Local Souls,” should put it to rest forever. A triptych of novellas set on the banks of the River Lithium in the same fictional town of Falls, N.C., where most of his work has taken place, “Local Souls” is a tour de force in the tradition of Hawthorne. It shows that Gurganus’s vast creative and imaginative powers, still rooted in the local, are increasingly universal in scope and effect. The book is an expansive work of love with not a sentence that (as Gurganus once said regarding Hannah) “hasn’t first been sung aloud at 3 a.m. beside some river at a hunting camp.” The prose is taut with the electric charge of internal rhyme, assonance and alliteration. Each touch yields an invigorating shock: “Numbers numbed the male ache, offered some sort of splint. They spared men the slack wet press of full female Emotion.” Or: “Student adolescence keeps walls infused with a sebaceous sweetness akin to curry.” Or: “Even to herself she seemed overdetermined, annealed, fused too early by some smelter’s blast into being one thing only.”