oasis
A lone palm tree and a spring in the middle of a sandy desert is the typical image that people have of an oasis. This is a fairly accurate picture, though an oasis can be small or very large. An oasis is any fertile area in a desert that has a supply of freshwater.
Oases provide rest, shade, food, and water for nomads as they travel their territory and to other people following trade routes. Some peoples have considered oases to be sacred places.
A permanent oasis is found where an underground water source exists. Sometimes the water springs naturally from the ground. Other times it is so deep that people must drill down to reach it and bring it up to the surface. The actual origin of the water may be hundreds of miles away. The water flows underground until it comes to the surface at the oasis.
Some oases exist only temporarily because the water supply is not constant. In the Sahara of Africa, for example, dry streambeds called wadis sometimes fill with water, which allows plants to grow. In other places, extra rain may fall in high areas of regions that are mostly dry. One example is the highlands of the Arabian Peninsula.
Some oases are big enough to support permanent settlements. The ancient region known as Mesopotamia (now Iraq) is a fertile floodplain located between the Tigris and Euphrates rivers. It was the site of some of the world's earliest civilizations. The Al Gutah oasis in Syria is the site of the city of Damascus. The Najran oasis, in the southwest corner of Saudi Arabia, has long been a center of rest, refreshment, and trade. In ancient times it was a major stop on the route of traders carrying frankincense and myrrh. Today it serves the nomadic Bedouins who travel from the desert to buy food and other goods.
Oases usually can support farming, and sometimes enough crops are produced that food can be exported. Oasis towns often are built on rocky hillsides, with the fertile land below used for growing crops.
Date palms are an important part of the plant life at oases. They have long roots that can reach the underground water. The palms form a canopy under which smaller trees, vines, and plants can grow. The smaller trees produce apricots, pears, oranges, olives, and pomegranates. Melon
