Explore how half of Earth's water originated from the planet's inception and how the other half was deposited by comets. Earth the Biography: Oceans : MON JULY 14 10P et/pt : http://channel.nationalgeographic.com/series/earth-the-biography/ Author: NationalGeographic Keywords: Environment; POP: Our Changing World; oceans; water; earth biography; planet; rivers Added: July 10, 2008
