Comment: 00:40 - 02:05 (01:25)
Source: Annenberg/CPB Resources - Earth Revealed - 19. Running Water I: Rivers, Erosion and Deposition
Keywords: introduction, "James Sadd", "Herodotus", "Pierre Perrault", river, water, Nile, rainfall, discharge, "River Seine", France, "drainage basin", civilization
Our transcription: This ancient meandering river provided sustenance for one of the earliest civilizations on Earth.
The culture which thrived along its fertile valleys forever changed Western Civilization.
Egypt, said Herodotus, is the gift of the Nile.
Puzzled by the source of all this water, many early philosophers theorized that the waters of the Nile, as well as all other rivers, originated from a system of boundless underground fountains.
Then, in the Seventeenth Century, French scientist, Pierre Perrault, conducted a simple experiment that would yield a startling discovery.
Perrault reasoned that rivers transport snow and rain from the land to the ocean.
To test this hypothesis, he compared rainfall with the flow or discharge of a river.
He first measured the amount of water flowing annually in the River Seine in France.
Then, he calculated rainfall for the upstream drainage basin surrounding the river.
Perrault found, to his surprise, that rainfall was six times as large as the flow of the river.
Geology School Keywords