(ËvÉr bÉl) adj. 1. of or consisting of words: verbal ability. 2. spoken rather than written; oral: verbal communication. 3. concerned with words only, rather than with the ideas, facts, or realities expressed: a purely verbal distinction. 4. corresponding word for word; verbatim: a verbal translation.
Because their hypothesis requires that Earth arose from water-containing materials already present in the inner solar system, it's called the wet-accretion hypothesis. Most of Earth's water has an indigenous origin, says Drake.
The second theory holds that the Earth, Venus, Mars and Mercury would have been close enough to that proto-solar nebula that most of their water would have been vaporized by heat; these planets would have formed with little water in their rocks. In Earth's case, even more water would have been vaporized when the collision that formed the moon happened.