Rivers can run on the surface of the earth, or possibly underground, carving out caverns along the way. Occasionally, a watercourse dies and sinks into the ground before reaching another river, lake or ocean, but this is rare. Some so-called rivers, such as the Santa Cruz River in Arizona, are dependent solely on rainfall, but the vast majority of rivers carry waters from glacier melt, springs, other rivers and streams, as well as from headwaters in mountains, meeting with other rivers or lakes, seas or oceans. Water, of course, seeks its own level, running from higher to lower elevations. A river can flow north, south, east or west.
As long as the West has been known, there has been a controversy over which of two rivers is the longest, the Nile in Egypt or the Amazon in South America. The Nile, for years considered the longest in length, measures a distance of over four thousand miles, with the Amazon coming in second, at about 3,900 miles. These numbers do not reflect the depth of the controversy, since the numbers vary according to the resource consulted. For example, the length of the Nile varies from 4,132 miles to 4,180 miles - the Amazon from 3,912 to 3,976 miles. And if measurement of flow or depth is taken into account, the Amazon wins, as it outflows as much as 20% of the Earth's fresh water into the Atlantic. The Amazon's depth is about 10 times greater than that of the Nile.
A recent expedition of the Brazilian Institute of Geography and Statistics established a claim that the Amazon is 65 miles longer than the Nile. River length is muddied by the difficulty of determining the exact beginning of a river. Sources, hidden in impossibly remote locations, require arduous expeditions to find. The Nile's source is said to stem from tributaries of Lake Victoria in Africa, but their beginning is unclear. The recent information from Brazil puts the Amazon's beginning on an icy mountaintop called Mismi in Southern Peru. The controversy rages on and surely more measurements will follow.
A similar controversy eddies around the length of the next two longest rivers on Earth, the Yangtze in China, and America's Mississippi. These two rivers vie for third and fourth in length, each sometimes occupying third place. Regardless of length, the majesty and vitality of these rivers is unsurpassed; catastrophic floods bring both the curse of devastation and the blessing of fertile soil and irrigation. Life flows in these mighty rivers.
