Description: Africa, the second largest continent, is a mix of steamy rainforests, vast grasslands, and arid deserts. It has no long mountain ranges, but is home to the world's largest hot desert, the Sahara, and its longest river, the Nile. The featured area is the central South Atlantic coastal region of Namibia, including the cities of Walvis Bay and Windhoek.
Description: A vast alluvial fan blossoms across the desolate landscape between the Kunlun and Altun mountain ranges that form the southern border of the Taklimakan Desert in China’s XinJiang Province.
Description: Vivid colors belie the arid landscape of northern Chile where the Atacama Desert, one of the world's driest, meets the foothills of the Andes. Here salt pans and gorges choked with mineral-streaked sediments give way to white-capped volcanoes.
Description: Australia is the smallest, and flattest, of all the continents. Its surface details are largely the result of erosion. Many rivers drain into the continent's harsh, arid interior, where they terminate in salt lakes that are dry for most of the year. Australia's coastal regions, however, are famous for astounding biodiversity, from the Great Barrier Reef in the northeast to Shark Bay in the west.
Description: Rising unexpectedly from the heart of the Namib Desert in northern Namibia, the Brandberg Massif is an exhumed granite intrusion. Unique plant and animal communities thrive in its high-altitude environment, and prehistoric cave paintings decorate walls hidden in its steep cliffs.
Description: Named after the ancient Mayan Province of Kimpech, the state of Campeche comprises much of the western half of Mexico's Yucatan Peninsula. Rivers in southern Campeche drain into the immense Terminos Lagoon, the entrance to which is protected by a long barrier island, Isla Del Carmen.
Description: Known for its beaches and resort hotels, Cancun lies at the tip of Mexico's Yucatan Peninsula. Inland from this tourist mecca, however, lies a sparsely populated tropical scrub forest that shelters the ruins of ancient Mayan cities.
Description: Snow-capped Colima Volcano, the most active volcano in Mexico, rises abruptly from the surrounding landscape in the state of Jalisco. Colima is actually a melding of two volcanoes, the older Nevado de Colima to the north and the younger, historically active Volcan de Colima to the south. Legend has it that gods sit atop the volcano on thrones of fire and ice.
Description: Along the southern coast of the Netherlands, sediment-laden rivers have created a massive delta of islands and waterways in the gaps between coastal dunes. After unusually severe spring tides devastated this region in 1953, the Dutch built an elaborate system of dikes, canals, dams, bridges, and locks to hold back the North Sea.
Description: Utah’s Green River flows south across the Tavaputs Plateau (top) before entering Desolation Canyon (center). The Canyon slices through the Roan and Book Cliff--two long, staircase-like escarpments. Nearly as deep as the Grand Canyon, Desolation Canyon is one of the largest unprotected wilderness areas in the American West.
Description: 142 million years ago, an asteroid or comet slammed into what is now the Missionary Plains in Australia's Northern Territory, forming a crater 24 kilometers in diameter and 5 kilometers deep. Today, like a bull's eye, the circular ring of hills that defines Gosses Bluff stands as a stark reminder of the event.
Description: Dark-colored volcanic cones sprout from an ancient lava field known as Harrat Al Birk along Saudi Arabia's Red Sea coastline. Many such lava fields dot the Arabian Peninsula and range in age from 2 million to 30 million years old.
Description: Soaring, snow-capped peaks and ridges of the eastern Himalaya Mountains create an irregular white-on-red patchwork between major rivers in southwestern China. The Himalayas are made up of three parallel mountain ranges that together extend more than 2,900 kilometers.
Description: Fed by multiple waterways, Brazil's Negro River is the Amazon River's largest tributary. The mosaic of partially-submerged islands visible in the channel disappears when rainy season downpours raise the water level.
Description: Meandering wadis combine to form dense, branching networks across the stark, arid landscape of southeastern Jordan. The Arabic word "wadi" means a gulley or streambed that typically remains dry except after drenching, seasonal rains.
Description: The eastern side of Russia's Kamchatka Peninsula juts into the Pacific Ocean west of Alaska. In this winter image, a volcanic terrain is hidden under snow-covered peaks and valley glaciers feed blue ice into coastal waters.
Description: Like frantic brushstrokes, fire scars cover the arid landscape near Lake Amadeus (upper right) in Australia's Northern Territory. Lake Amadeus is rich in salts that have been leached out of underlying sediments. When dry, its lake bed is transformed into a glistening sheet of white salt crystals.
Description: Surrounded by sand dunes, Lake Disappointment is an ephemeral salt lake in one of the most remote areas of Western Australia. An early explorer supposedly named the lake in 1897 after following a number of creeks that he thought would lead to a large lake; they did, but the lake's extremely salty water was not drinkable.
Description: Mexico and Central America together form the southern half of the North American continent. From the rugged deserts of the Baja Peninsula to the steamy rain forests of Panama, the region is a land of great contrasts.
Description: Turbid waters spill out into the Gulf of Mexico where their suspended sediment is deposited to form the Mississippi River Delta. Like the webbing on a duck's foot, marshes and mudflats prevail between the shipping channels that have been cut into the delta.
Description: Located on the Italian island of Sicily, Mt. Etna is one of the world's most active volcanoes. In this image of the volcano in 2001, a plume of steam and smoke rising from the crater drifts over some of the many dark lava flows that cover its slopes.
Description: Coursing through parched, landlocked Mali in Western Africa, the Niger River flows north through an ancient sand sea before turning sharply east to skirt the edge of the dune-striped Sahara. At the confluence of the Bani and Niger Rivers is an island delta complete with narrows, twisting waterways, lagoons, and tiny islands.
Description: Like dark fingers, cold ocean waters reach deeply into the mountainous coastline of northern Norway, defining the fjords for which the country is famous. Flanked by snow-capped peaks, some of these ice-sculpted fjords are hundreds of meters deep.
Description: The pockmarked terrain of Pinacate National Park in Mexico's Sonora Province is evidence of a violent past. Among hundreds of volcanic vents and cinder cones are rare maar craters, formed when rising magma met underground water to create pockets of steam that blew nearly circular holes in the overlying crust.
Description: The mountainous outcrops of Jebel Auenat rise 6000 feet above the barren, uninhabited plains of the Libyan Desert. The frontiers of Libya, Egypt and Sudan meet amidst the rugged granite of Jebel Auenat. The mountains are remnants of an ancient granitic dome. Rivers of sand meander around them, swept across the desert pavement by northeasterly winds.
Description: Like a many-faceted jewel fashioned in an indigo setting, the Shetland Islands lie 210 kilometers north of the Scottish mainland in the North Atlantic Ocean. Despite their 60 degree north latitude, the Shetlands enjoy a relatively temperate climate thanks to the warming influence of the Gulf Stream.
Description: Resembling splotches of yellow and green paint, salt-encrusted seasonal lakes dot the floor of Western Australia's Shoemaker impact structure. The structure was formed about 1.7 billion years ago and is currently the oldest known impact site in Australia.
Description: South America stretches more than 7,500 kilometers from the warm Caribbean Sea almost to Antarctica. Waters from the eastern slopes of the Andes Mountains drain into mighty rivers, such as the Amazon, that traverse rain forests, grassy plains, and dry plateaus to eventually reach the Atlantic Ocean.
Description: France's famed Provence region meets the Mediterranean as a gentle curve intricately sculpted into sheltered bays and fringing peninsulas. The ancient port of Marseilles, the country’s second largest city, nestles in the large bay at the lower left corner of the image.
Description: Elusive, but ecologically vital, Namibia's Ugab River only flows above ground for a few days each year. The subterranean waters underlying this ephemeral river, however, are shallow enough in places to fill hollows and sustain a wildlife population that includes the rare desert elephant.
Description: Valley glaciers appear as fingers of blue ice reaching out from the Vatnajokull Glacier in Iceland's Skaftafell National Park. The park lies on southern edge of Vatnajokull, Europe's largest ice cap.
Description: As air flows over and around objects in its path, spiraling eddies, known as Von Karman vortices, may form. The vortices in this image were created when prevailing winds sweeping east across the northern Pacific Ocean encountered Alaska's Aleutian Islands.
Description: Western Asia, the world's largest continent, occupies one-third of the Earth's landmass. Although divisions are somewhat arbitrary, Western Asia encompasses the Middle East and countries that surround the Caspian Sea, including Kazakhstan and Russia.
Description: An intricate maze of small lakes and waterways define the Yukon Delta at the confluence of Alaska's Yukon and Kuskokwim Rivers with the frigid Bering Sea. Wildlife abounds on the delta and offshore where sheets of sea ice form during the coldest months of the year.