Chapter 13—The Black River
The portion of the terrestrial globe which is covered by water is estimated at upwards of eighty millions of acres. This fluid mass comprises two billions two hundred and fifty millions of cubic miles, forming a spherical body of a diameter of sixty leagues, the weight of which would be three quintillions of tons. To comprehend the meaning of these figures, it is necessary to observe that a quintillion is to a billion as a billion is to unity; in other words, there are as many billions in a quintillion as there are units in a billion. This mass of fluid is equal to about the quantity of water which would be discharged by all the rivers of the earth in forty thousand years.
During the geological epochs the ocean originally prevailed everywhere. Then by degrees,
