Thursday, May 7, 2015

Himalayan rivers and snow from the space station

(Source: NASA)

As the International Space Station flew 418 kilometres above the Himalaya Mountains, the crew snapped this photograph of the snow-capped panorama unfolding near the China-India border.

This image taken on April 8, 2015 - just over two weeks before the magnitude 7.9 earthquake hit nearby Nepal - shows the foothills of one of the main ranges of the Himalayas, where peaks cast strong evening shadows on the snow.

The mountains in this image reach altitudes of 5200 metres. Other peaks just beyond the upper edge of the image reach even higher altitudes of more than 6500 metres.

The flat areas at the base of the mountains are ancient alluvial fans, filled with sediment eroded from the high mountains over millions of years.

Snow cover highlights these strikingly smooth surfaces, which are cut through by a trellis-like network of gullies casting sinuous shadows.

The large river on the right of this scene has cut a 500-metre-deep canyon.

Although the rivers in this image drain northward from the Himalayas, they ultimately flow back to the south, accumulating in the Sutlej River (out of shot) which passes through the mountains toward the lowlands of Pakistan and, finally, empties out into the Arabian Sea.

The Himalayan Mountains are among the youngest mountain ranges on the planet, and were formed by the collision of the Indian and Eurasian tectonic plates along a 2400 kilometre arc which reaches its greatest elevation of 8848 metres at Mount Everest.

The Indian plate is continuing to drive horizontally beneath the Tibetan Plateau at a rate of about 67 millimetres per year, creating uplift in the Himalayas of about five millimetres every year and causing occasional large earthquakes such as the recent Nepalese quake.

EARTH IMAGE by Stuart Gary
ABC

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