Gemsbok A gemsbok gallops through the loose sand of Namibia’s Namib Desert. Considered one of the world’s oldest deserts, the Namib contains sand dunes that reach some 1,000 feet (305 meters) in height.

Stonehenge Stonehenge, on Salisbury Plain, is arguably England’s greatest archaeological treasure. Though weathered and broken, its ruins are a window on a prehistoric world, guarding secrets after more than 4,500 years. Here, lights from the nearby town of Amesbury lend a lavender glow to the sky above the enigmatic monument. Photograph: Richard Nowitz

Oregon Sea Stacks Sea stacks, like this one shaped like the prow of a ship in Cape Kiwanda State Park, Oregon, are chunks of isolated rock resistant to erosion. They start as part of a headland or sea cliff connected to land. Smashing waves erode the softer rock, leaving harder rock behind in the form of sea stacks. Photograph: Tyrone Turner

Australian Sea Lions The threatened Australian sea lion is found only in the Great Australian Bight, which arcs around the southern shore of the continent. The mammal is distinguished by an unusual breeding cycle that occurs every 18 months and has pups suckle for a year and a half. Photograph: David Doubilet