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Archive for November 27th, 2009

Steppe-like Plains of Argentine Patagonia

38.6S 68W

November 27th, 2009 Category: Lakes, Rivers

Argentina - October 6th, 2009

Argentina - October 6th, 2009

The landscape of Argentine Patagonia appears mostly tan and brown in color, as it is for the most part a region of vast steppe-like plains. These plains rise in a succession of abrupt terraces about 100 metres (330 ft) at a time. In the hollows of the plains are ponds or lakes of brackish and fresh water.

Several such lakes can be seen in the upper left quadrant, near the Neuquén River (above) and the Limay River (below). All of these are artificial: the reservoir to the south was created by the El Chocón Dam, the two to the north are part of the Cerros Colorados Complex, and the final one to the east is Pellegrini Lake.

Sandstone Buttes in Northern Arizona, USA

35.3N 110.3W

November 27th, 2009 Category: Snapshots

USA - November 15th, 2009

USA - November 15th, 2009

Clusters of high sandstone buttes characterize this part of the Colorado Plateau in Navajo County, in the state of Arizona, USA. The largest buttes in this orthorectified image reach 6400 feet above the valley floor.

A butte is a conspicuous isolated hill with steep, often vertical sides and a small, relatively flat top; it is smaller than mesas, plateaus, and tables. In some regions the word is used for any hill; however, in differentiating mesas and buttes, geographers use the rule that a mesa has a top wider than its height, while a butte’s top is narrower.

The buttes here are located in Navajo County, in the northern part of Arizona. The county contains parts of the Hopi Indian reservation, the Navajo Indian Reservation and Fort Apache Indian Reservation.

According to the U.S. Census Bureau, the county has a total area of 9,959 square miles (25,795 km²), of which, 9,953 square miles (25,779 km²) of it is land and 6 square miles (16 km²) of it (0.06%) is water.

Green Fields of the Gezira Scheme in Sudan – November 27th, 2009

14.5N 33.1E

November 27th, 2009 Category: Image of the day, Rivers

Sudan - October 7th, 2009

Sudan - October 7th, 2009

The green irrigated fields of the Gezira Scheme in Sudan’s Al Jazirah state fill the land between the Blue (right) and White Nile (left) Rivers. The Gezira Scheme, begun by the British in 1925 to foster cotton farming, distributes water from the Blue Nile through canals and ditches to tenant farms lying between the two rivers.

Since the start of the scheme, Al Jazirah has become Sudan’s major agricultural region, with more than 2.5 million acres (10,000 km²) under cultivation. The initial development project was semi-private, but the government nationalized it in 1950. Cotton production increased in the 1970s but by the 1990s increased wheat production has supplanted a third of the land formerly seeded with cotton.

Volcanoes Near Lake Taupo, New Zealand

38.7S 175.8E

November 27th, 2009 Category: Lakes, Rivers, Volcanoes

New Zealand - November 13th, 2009

New Zealand - November 13th, 2009

Several volcanoes are visible near Lake Taupo, the large lake at the upper right, in this orthorectified image of New Zealand’s North Island. Following the Tongariro River, one of the lake’s main tributaries, upstream from the lower end of the lake, one comes to a smaller lake known as Lake Rotoaira.

Between these two lakes is Mount Pihanga, a 1325m volcanic peak on the North Island Volcanic Plateau. Another smaller body of water, Lake Rotopounamu, is at the north-west foot of the mountain. Mt. Pihanga and Lake Rotopounamu are part of the 5,129ha Pihanga Scenic Reserve, which in 1975 was added to the Tongariro National Park.

South of Mount Pihanga is Mount Tongariro, a volcanic complex located 20 kilometres to the southwest of Lake Taupo. It is the northernmost of the three active volcanoes that dominate the landscape of the central North Island. This volcanic massif, often simply referred to as Tongariro, has a height of 1,978 metres.

The volcano consists of at least 12 cones; Ngauruhoe, while often regarded as a separate mountain, is geologically a vent of Tongariro. It is also the most active, having erupted more than 70 times since 1839.

Continuing south of Ngauruhoe is Mount Ruapehu, an active stratovolcano at the southern end of the Taupo Volcanic Zone. It is 23 kilometres northeast of Ohakune and 40 kilometres southwest of the southern shore of Lake Taupo, within Tongariro National Park.  Ruapehu is one of the world’s most active volcanoes and the largest active volcano in New Zealand. It is the highest point in the North Island and includes three major peaks: Tahurangi (2,797 m), Te Heuheu (2,755 m) and Paretetaitonga (2,751 m).