SAHARA DESERT

The Sahara Desert is one of the world's most recognizable places. It is also one of the harshest places to live. The desert stretches 3,000 miles across the northern part of Africa. More than one quarter of its surface is sand dunes, some as high as 500 feet. A handful of mountains can be found in the Sahara, with the summit being Mount Koussi, at 11,204 feet. As would be expected, the climate of the Sahara Desert is hot and dry. The desert is dominated by strong winds, which blow the sand from place to place, leaving landscapes to change regularly. Timbuktu, one of the most famous cities in the world, is being covered bit by bit in sand. Many of the houses in this remote city are already below ground level.

The northern part of the desert is subtropical and has cold winters and two rainy seasons. The dry southern desert has a rainy season and a mild, dry winter. Rainfall in either half is never very significant, numbering less than 5 inches for an entire year. When the rain does come, though, it comes sometimes with ferocity. Amazingly, some people have been known to drown in the Sahara because of the sweeping floods that often accompany a freak rainstorm that showers a sandy plain.

The Sahara is not all sand by any means. Hundreds of miles of surface and underground water dot the landscape and sub landscape. Large bodies of water include the Nile River and Lake Chad. Smaller bodies of water known as oases can be found nearly everywhere. Some maintain a steady supply of water, but some dry up not long after they have formed. Waterfalls are not uncommon but appear strikingly out of place in their sandy surroundings.

Another common feature in the desert is rocks. Plateaus contain large boulders, and full-blown mountains are not uncommon (and get lots of snow in the winter). Some mountains are volcanic as well and are a mix of live and dormant. Grasses, trees, and plants can be found in the Sahara, although nearly all species are hearty, drought-resistant survivors. Animals can be plentiful, including hundreds of species of reptiles and mammals. The number of species of birds alone tops 300. Many of those species are migratory, however, able to move quickly to a new home if their water supply literally dries up. As for people, not surprisingly, the Sahara Desert has one of the lowest population densities on the planet. In the 3.5 million square miles of sands, mountains, and waterways live just 2.5 million people. Obviously, the population is the largest near lakes and rivers. Even so, the majority of the people are nomads. The climate of the Sahara has gradually gotten harsher. Archaeological remains point to water sources much more widely available and a population much more spread out.

THE NILE

The Nile is the world's longest river at 4,135 miles. It has two sources, one at Lake Victoria, in Uganda (the White Nile) and one at Lake Tana, in Ethiopia (the Blue Nile). The entire Nile River Delta is estimated to drain an area of 1,293,000 square miles. This area is so vast that it has a number of different climate areas. North, in Egypt and Sudan, rainfall is sparse. More to the south, in and around Ethiopia, rainfall is heavy, contributing to the floodwaters that rush downstream and eventually create the wonderfully fertile soil that supports so much of life in Egypt and Sudan. Dams, the most notable being the Aswan High Dam, have been built along the route to prevent massive flooding of populated areas. The Nile River Delta is home to many species of animals, including crocodiles, turtles, baboons, wildebeest, and more than 300 species of birds, including fishing eagles, ibis, and the Nile Valley Sunbird.

The ancient Egyptians called the river Ar or Aur, meaning "black," because of the black sediment left behind after the frequent river floods. The ancient Greeks called the river Kem, which translates into "black" as well. But it is as the Nile that we know this river today. Nile comes from the Greek Neilos, which means "river valley."

The people who lived along the Nile in ancient times used the river for agriculture and transportation. That hasn't changed, although the methods of agriculture and transportation have. Steam ships are still used in Egypt and Sudan, to transport goods. The Okavango River is the main river running through the Delta, but other rivers can be found there, too, including the Boro, the Nghabe, and the Boteti. People live here, in the middle of the desert, because they can depend on the rivers to bring them water and goods. And because the river is so large, it supports many kinds of animals not usually found in the desert, including crocodiles, hippopotamuses, and more than 80 species of fish. Rivers today still bring much-needed water to people in all civilizations. Many agricultural areas now have canals and other methods of irrigation designed to transport water from place to place. Rainwater is collected and stored, and river water is stored in dams and reservoirs.

EGYPT GEOGRAPHY