Deserts are dry – very dry! Deserts are vast areas of dry sand, dry rocks and mountains. This is because deserts do not get enough rainfall for plants and grasses to live. About one eighth of the world’s land surface is desert. Only specially adapted plants such as cactuses and certain lizards can survive in those places. Great dust storms can be frequent as there is no water to hold down the sand. The fertile top soil is blown away and the land becomes useless. Deserts form due to many reasons – including due to the work of men. One cause is when wind travels in one direction for long distances over dry land. Then its moisture content falls and it becomes dry like the desert itself. It even dries up any available moisture on the land it passes over. In tropical areas, in daytime temperatures can go very high and so the wind becomes like a fiery furnace blast! The sand can melt to form crystals of glassy sand called ‘sand roses.’ No plants, no trees and no animals – nothing can survive except in occasional deep, cool ravines that contain water. Also, when moist air is forced over high mountains, it first rains on one side but the other side of the mountain gets no rain. The wind becomes dry and then dries out the land, slowly forming desert. But deserts can form rapidly. For example the Isarn region of Eastern Thailand is well inland – far from the sea. Around the 1990s, it was rapidly drying out! It was an emergency! Part of the Mekong River had to be diverted by the Thai army to prevent desert taking over. Luckily there was that great river nearby to supply life-giving water and so protect the top soil. The Sahara Desert in North Africa was the granary of the cruel Roman Empire – 2000 years ago. It was green and fertile and had rainfall – water! They grew food and they made the most delicious, fruity wines. Now it is the world’s biggest desert, and it is expanding in some places. It is 3,200 miles from east to west and 800 to 1400 miles from north to south. It is a vast emptiness now. There are mountains, gullies and ravines where a few plants and cactuses can cling to life, those that need only a little water. But fortunately, this desert has ‘oases’ or watering holes, where water springs up naturally from the ground. These oases are green and buzzing with life – trees, animals, birds and insects! Farming can be done! Camel trains use these oases when they cross the desert carrying goods to oases and towns in and around the desert. The Saudi Arabian peninsula has many different animals surviving precariously in nooks and crannies of the terrain. This tells a story: once, not so long ago, the land was green and fertile with much wildlife. How did it become so dry and sandy? I suggest human activity! It was the method of hunting, to set fire to large areas of trees and plants up-wind of the animals. The wind would carry the fire miles and miles. Small animals would be caught and roasted by the raging fires. But the people did not realize the damage they were doing – they had killed off a certain percentage of plant life. This allowed the wind to carry away the fertile top soil leaving only sand and stones. Something similar has already happened to vast areas of India, too. By destroying trees, plants and bushes, ignorant people do not realize what they are doing! So, people misuse the land and then it becomes useless desert! PH. 16/7/2011