Abstract
Extremely low abundance of carbonate rocks in the Archean, constant δ13C difference between the carbonate and organic carbons throughout the geologic time, and many other geologic evidences seem to support the intermittent degassing through the geological history. This proposal is in contrast with the catastrophic early degassing (OZIMA, 1978) and also the continuous degassing (RUBEY, 1951). An argon isotope ratio of 295.5 can be consistently interpreted by the survival on the earth's surface of argon gas of 1.7×l017g which is attributed to the primordial solar nebula.
