A rugged, snow-covered mountain range, a rocky crag illuminated against sparse pines, a pristine river rushing over huge boulders: this is a visual anthem to one of America’s scenic splendors, the Grand Teton range near Yellowstone. What gives this painting its power? The grand scale, for one, but also a prismatic use of color. Notice the subtle shading at the edge of the hillside, where it meets the mountains, and the brilliance with which the sandy-colored rock anchors the image, at right. Moran specialized in this kind of sweeping, dramatic landscape, and paintings like this one helped persuade Congress to designate Yellowstone as the first national park.