51 Photos - Oct 1, 2015
Photo: Photo: Photo: Photo: 09-4-4533. The Anavilhanas, the name given to around 350 forested islands in Brazilís Rio Negro, form the worldís largest inland archipelago. Covering 1,000 square kilometers of Amazonia, they start 80 kilometers north-west of Manaus and stretch some 400 kilometers up the Rio Negro as far as Barcelos.  Their formation dates back to the last Ice Age when changes in the flows of rivers entering the Rio Negro produced accumulations of sediment which, over time, resulted in sandbars and islands. Since water levels change with the seasons by as much as 20 meters, the Anavilhanas are themselves ever-changing, with channels, sandbars and lagoons appearing during the dry season and some small islands vanishing when waters rise. Many of the larger islands, though, are self-contained parcels of rain forest. Brazil. May 2009.Photo: The Arctic National Wildlife Refuge (ANWR) in north-eastern Alaska is the largest wildlife refuge in the United States, covering no fewer than six ecozones and stretching some 200 miles (300 kilometers) from north to south. Along its northern coast, barrier islands, coastal lagoons, salt marshes and river deltas of the Arctic coastal tundra provide a marvelous habitat for migratory water birds. Coastal land and sea ice are sought by caribou seeking relief from insects during the summer and by Arctic bears for hunt-ing seals and breeding during winter.This photograph was taken in the eastern part of the Brooks Range, which rises to over 9,800 feet (3,000 meters); the rugged stretch of mountains is sliced by deep river valleys and numerous glaciers. The immense variety of microclimates results from the collision of cold air from the Arctic and hot air coming from the Yukon River region of central Alaska. Alaska. USA. June and July 2009Photo: Photo: Photo: Big Horn Creek in Kluane National Park and Reserve, located in a nearly inaccessible region of Canada’s Yukon Territory, near the border with Alaska.Photo: Photo: Photo: Photo: Photo: Photo: 05-1-450/43.  Iceberg between Paulet Island and the South Shetland Islands on the Antarctic Channel.  At sea level, earlier flotation levels are clearly visible where the ice has been polished by the ocean’s constant movement. High above, a shape resembling a castle tower has been carved by wind erosion and detached pieces of ice.  The Antarctic Peninsula. January and February 2005.Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Ethiopia, 1984Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: The first day of installation of the camp of Benako for the Rwandan Tutsi and Hutu Refugees, Tanzania, 1994Photo: Tigray, Ethiopia, 1985Photo: Marine iguana (Amblyrhynchus cristatus). This animal is a perfect example of adaptation and evolution. The first marine iguanas apparently came to the archipelago from the American mainland, almost 620 miles (1,000 kilometers) to the east. They were probably transported by sea currents atop tree trunks, pieces of land with foliage and other objects floating on the water and, once here, they were forced to adapt to local conditions. A smaller number of these migrants remained land iguanas and can be found on only a few islands, but the majority evolved into ma-rine animals: they learned to swim, to feed on seaweed, to dive and to remain submerged for long stretches; they even developed special glands to excrete excess salt from their food intake. It is the only type of iguana in the world able to live in salty waters. Galápagos. Ecuador. January, February and March 2004Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: