Mark Slade, age 10, of Monroe, La., for his question:
WHEN WAS THE MISSISSIPPI RIVER FORMED?
Scientists tell us that the Mississippi River was probably formed about two million years ago just as the Pleistocene ice age was starting. During this period of time, much of North America was covered with glaciers.
As the ancient ice formations melted, water formed what is now the Missouri and Ohio Rivers and flowed into the Mississippi.
Many Indian tribes, including the Illinois, the Kickapoo, the Santee Dakota and the Ojibway, lived in the upper Mississippi Valley. The name "Mississippi," which means "big river," comes from these tribes.
The lower Mississippi Valley was the home of such tribes as the Chickasaw, the Chocktaw, the Natchez and the Tunica.
The Mississippi River is the longest river in the United States and is also the nation's chief inland waterway. Ships can travel on this river for more than 1,800 miles.
The mighty river starts as a clear, small flow of water that rushes out of Lake Itasca in northwestern Minnesota. The Mississippi flows northward and then eastward, linking a series of lakes. It begins to curve southward near Grand Rapids, Minn.
As the Mississippi flows between the cities of Minneapolis and St. Paul, it is joined by the Minnesota River. Beginning with the spot where the Mississippi meets the St. Croix River, it forms the boundary between the states of Wisconsin and Minnesota.
The Mississippi River also makes up part of the boundaries of eight other states: Illinois, Kentucky, Tennessee, Mississippi, Iowa, Missouri, Arkansas and part of Louisiana.
Above St. Louis the muddy waters of the Missouri River meet the clear water of the Mississippi. The waters then mix and the Mississippi takes on the muddy color for which it is known in the south.
The Ohio River meets the Mississippi at Cairo, I11. Here the volume of water in the Mississippi River is doubled. This is also the division between the upper Mississippi and the lower Mississippi.
The Mississippi has a number of nicknames. Some call it "Old Man River" and others call it "Old Muddy."
The river is 2,340 miles long. The Mississippi and its tributaries drain a vast basin that covers 1,247,300 square miles.
As the Mississippi River reaches the Gulf of Mexico, it deposits large amounts of silt to form a delta. The Mississippi Delta covers more than 15,000 square miles.
There seems to be an endless supply of water in the Mississippi River. The giant waterway empties over 640,000 cubic feet of water every second into the Gulf. This comes out to about 133 cubic miles of water each and every year.