Falls at Toltec Gorge, Thomas Moran
Link is to zoomable version on Google Art Project; 1000 Museums has version online that you can download here; original is in the Oklahoma City Museum (no collections online).
When Moran turns his Turner-influenced eye to the rough textures of the American landscape, the results are usually amazing. I love Hudson River school landscapes like this that incorporate strong foregrounds, making them simultaneously grand and intimate.