What is the author's style in Green Hills of Africa by Ernest Hemingway?

By the time this book was written (in the early 1930s, when the author was in his mid thirties), Ernest Hemingway was a successful writer, a known personality, and well traveled. He hadn't yet published his most famous works (such as The Old Man and the Sea, A Farewell to Arms) and hadn't yet acquired the celebrity that came with the publication of those books and the associated revelations of his lifestyle, but he had already lived according to the dictates of a deep seated personal, cultural and artistic restlessness.