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 Dibartolo/UNEP/Topham |
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 Fritz Polking/Still Pictures |
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| Once they were an ocean reef; now the Guadalupe Mountains rise out of the Texas and New Mexico regions of the Chihuahuan desert. The limestone range bears witness to marine life from an inland sea 240 to 280 million years old. The reef was buried for tens of millions of years before being pushed up by movement of the Earth's crust. As it rose, sulphuric acid in the water table dissolved the limestone from the bottom up, creating some of the world's longest caves. Scientists believe that the caves - the summer home for the migratory Mexican free-tailed bat - contain microbes with medicinal qualities. |
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| For most of the year the Rann of Kutch in India is a searingly hot, inhospitable lowland desert. But for four months this part of the Thar desert - spanning over 20,000 square kilometres of the Arabian Sea coast along the Indo-Pakistan border - floods about half a metre deep, thanks to the summer monsoon rains and the seawater driven into the area by wind and high tides. Then it teems with wildlife, serving as an important habitat for over 200 species of birds, including large migrating flocks of the greater and lesser flamingo, and 50 species of mammal, such as the endangered Indian wild ass - the last in Asia. |
 Ashok Jain/naturepl.com |
 Klein/Still Pictures |
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| It is quite an achievement to earn a nasty name in both a living and a dead language, but the thorny devil has achieved it; its Latin name, Moloch horridus, comes from a malevolent god or king. But its dragon-like appearance is offset by its size - only 15 centimetres long - and its behaviour. This lizard only attacks ants, eating them one at a time at a rate of up to 45 a minute. It has adapted to the desert by developing thousands of tiny grooves in its skin that collect dew and rainwater and channel the moisture to the corners of its mouth. |
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| There could hardly be a less promising place to find life: for 25 million years Lake Vostok has been buried under 4 kilometres of ice at the coldest recorded spot in the white desert of Antarctica. The size of Lake Ontario - and thus one of the world's largest freshwater lakes - it is thought to be kept liquid by geothermal heat. Biologists believe prehistoric microbes 500,000 to 1 million years old, left over from the time when the frozen continent's climate was temperate, may still be living in its waters. Studying them could shed light on the evolution of life on Earth. |
 V. Chistyakov/TopFoto |
 Martin Harvey/Still Pictures |
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| Crocodiles and the Sahara don't seem to go together - but they do. Tara Shine, a student at the University of Ulster, was told about them by local people while studying in Mauritania. She investigated, and there they were. The area can go without rainfall for eight months of the year, and so the crocodiles survive by crawling into burrows and caves and entering a dormant state called estivation - the warm-weather equivalent to hibernation - until rain creates wetlands for them. Scientists think they are remnants from when the Sahara was greener and wetter, thousands of years ago. |
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| Deep in the desert of Jordan, the lost city of Petra has been carved into the living rock. Homes, banqueting halls and great temples were chiselled by hand into sandstone cliffs by the Nabataeans, one of the most civilized peoples of antiquity. They harnessed natural springs to grow crops, tend lush gardens and sustain a population of 20,000 people. But the trade routes that supported the city changed, and Petra became deserted and forgotten, only to be rediscovered in the early 19th century by Johann Ludwig Burckhardt, a Swiss explorer who was the first outsider to see it for 500 years. |
 Ullstein-Klar/Still Pictures |
 N. Vignola/UNEP/Topham |
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| Where the world's driest desert meets its longest mountain range lies one of the most extraordinary places on Earth. The Valle de la Luna, squeezed between the Atacama desert and 6,000-metre Andean peaks, really does look like a piece of the moon. Created 22 million years ago by the folding of the Earth's crust, it is absolutely lifeless, so arid that not even insects can live there. Ancient volcanoes deposited rock and ash on the folds, and wind has carved the sedimentary rock - containing salt, gypsum, chlorate, borate and clay - into strange shapes, including gnarled and twisted sculptures, small sharply crested hills and massive dunes. |