Emerald Robinson: Hi! My name is Emerald Robinson and in this What Is video we are going to try to determine what exactly defines a river.
A river is a natural stream of fresh water that has a current and moves toward another body of water such as an ocean, lake, or another river. Rivers can be of different sizes and local terms can cause the actual definition of a river to be vague. What one person calls a river another might term a brook, a real, or a creek.
A river's origin is called its source. Since rivers flow downhill sources are usually high in the mountains where water comes from snow melt or an underground spring.
A river flows between its side or banks in what's called a channel. The channel increases its size as the river gains water from other smaller streams or tributaries. A river's journey ends when it meets a lake or the sea at a point called its mouth. Rivers play an enormous role in shaping the earth through erosion creating geological formations such as canyons. Rivers create as well as destroy. A river's mouth is often clogged by silt and dirt that has been carried down the river's path. This sometimes forms a land mass called a delta. Although there is a little disagreement among geographers it's generally accepted that the world's longest river is Egypt's Nile River which stretches over 4000 miles from Lake Victoria in Central Africa to the Mediterranean Sea. The biggest river though is unquestionably the Amazon River located in South America. Although it's not as quite as long as the Nile, it carries almost 20% of the world's fresh water in its bed as it flows from its source in Andes mountain of Peru to its mouth on the Atlantic ocean.