Desert

an arid waste. This definition excludes the icy wastes of Greenland and the Antarctic country, as well as the frozen, lifeless tundras of the Arctic coast.

A desert is not a rainless region, for there is no part of the earth's surface without rainfall; but it is a region deficient in rainfall. The Mojave Desert in Arizona has but two inches a year. The coast of Chile near the Pacific has been seven years without rain.

The desert zones of the world are two, one in the southern and one in the northern hemisphere. They lie approximately twenty-five degrees north and south of the equator, in the two belts of wind that blow from the east. In the northern hemisphere the Pacific winds are robbed of their moisture by the mountains of eastern Asia. This, the greatest desert region in the world, begins with the desert of Gobi on the border of China. It stretches westward through Turkestan, Persia, Arabia, and the Sahara of North Africa--a vast arid waste. Part of this desert is the highest plateau land on the face of the globe, and part lies below the level of the sea. It is interrupted by fertile valleys, by local showers from local sources, and especially by the valley of the Nile; but all in all its extreme length is a third of the distance around the globe. It includes an area of between six and seven million square miles. Were it not for the Mediterranean, Southern Europe would be a desert. In the western continent the arid belt begins west of the Mississippi and culminates, if we may so speak of a depression, in the Death Valley of California. In the southern hemisphere, the desert belt is less marked. It includes the interior of Australia, the Kalahari region of South Africa, and the rainless coast of northern Chile.

A large part of the world, formerly regarded as desert, has been reclaimed by irrigation and is now productive. There is no reason why deserts are deserts, save the want of water. They contain stupendous mountain walls and rocky ledges, as well as level plains. The rock elements are present that by disintegration and the decay of vegetable matter have produced the fertile soil of other regions. Possibly the winds that now blow may one day turn windmills that will raise water from the sea to convert millions of barren acres into rich fields and pastures. Leaving out of account semi-arid steppes and plains that produce at least scant pasturage, it is estimated that the deserts of the world cover 4,180,000 square miles of territory.

Among the phenomena of the deserts are vast shifting drifts of sand, often deep enough to bury the highest steeple or the tallest forest. The whirlwinds and the changes of temperature from freezing at night to 150 deg. at noon are to be dreaded.

See Sahara; Gobi; Oasis; Camel; Sirocco; Irrigation; Dune; Palm; Cactus