The Guardian newspaper put together an excellent collection nature photographs for auction for an Earth Day charity. I particularly like the pictures from the Franklin River, south-west Tasmania, Australia and Stone Canyon, Arizona/Utah, U.S.A.. Apart from the wonderful composition and spectacular lighting, I like the effort and meaning behind these images.
According to the Guardian, the Franklin River image was instrumental in preventing the flooding of the river for an hydroelectric dam. The Stone Canyon picture was used to try to have the area declared a national monument. I particularly appreciate the effort of Jack Dykinga, who took the Stone Canyon photo. He hiked up the slot canyon at 3:30 am in order to get the photograph at dawn; with their softer light and reddish tints, sunrise and sunset are the best times for photography.