Janet Steen, age 13, of Pittsburgh, Pa., for her question:
WHAT IS THE WORLD'S LARGEST RIVER?
There are many remarkable things about the Amazon River of South America. More than 200 separate rivers flow into it. An unusually high ocean tide occasionally overpowers the current at the Amazon's mouth. This action creates a wall of water called a bore that can measure up to 15 feet high as it rushes upstream. If you ask which is the world's longest river, it would be a matter of definition for you to pick the Nile River in Africa or the Amazon River in South America. The Nile is 4,145 miles long. Many say the Amazon is 4,007 miles long, but if you count the waterway through the straits of Breves and Boicui into the Para, the total length is 4, 195.
When you ask which river is the "largest," the Amazon would have to win the honors.
The largest river basin in the world is the one drained by the Amazon. It covers about 2.72 million square miles of land. All together, the Amazon has about 15,000 tributaries and subtributaries, four of which are more than 1,000 miles long.
The Amazon also wins honors for the greatest flow of water. An average of 4.2 million cubic feet of water per second is delivered into the Atlantic Ocean by the Amazon. During periods of full flood, this, total goes up to more than 7 million cubic feet of water per second. The lower 900 miles of the river averages 300 feet in depth.
At many points it is impossible for a person to see from one bank of the Amazon to the opposite shore. In many places it is more than six miles wide.
The Amazon River basin forms the world's largest tropical rain forest. The area is about two thirds as large as the area of the entire United States. Average temperature is about 85 degrees Fahrenheit with very little variation throughout the year. Rainfall ranges from 50 inches each year in low lying areas to more than 120 inches annually near the Andes Mountains.
Headwaters for the Amazon are high in the Andes Mountains of Peru in a small stream called the Apurimac River which lies 17,200 feet above sea level. It falls about 16,400 feet during the first 600 miles and only 800 feet during the rest of its trip to the Atlantic. The river flows at the rate of about 1.5 miles per hour during the dry season and increases to about 3 miles per hour during the time when the river is swollen by rain.
More than 3,000 different species of plant life have been found in the Amazon region. Thousands of different kinds of animals and freshwater fish are also residents.
During the 1800s, the Amazon basin was an important source of rubber but the demand ended when cheaper sources in Southeast Asia were found in 1910. At the present time the Brazilian government is working to attract more people and industries to the Amazon basin.