Atmosphere of Earth primarily hydrogen. There were probably simple hydrides such as those now found in the gas giants (Jupiter and Saturn), notably water vapor, methane and ammonia. Outgassing from volcanism, supplemented by gases produced during the late heavy bombardment of Earth by huge asteroids, produced the next atmosphere, consisting largely of nitrogen plus carbon dioxide and inert gases. A major part of carbon-dioxide emissions dissolved in water and reacted with metals such as calcium and magnesium during weathering of crustal rocks to form carbonates that were deposited as sediments. Water-related sediments have been found that date from as early as 3.8 billion
Gas-s-s-s military gas leak involving an experimental agent that kills everyone on Earth over the age of 25. (A cartoon title sequence shows a John Wayne-esque Army General announcing — and denouncing — the "accident"; the story picks up after the victims have died.) The lead characters, Coel and Cilla, are played by Robert Corff and Elaine Giftos, and the cast features Ben Vereen, Cindy Williams, Bud Cort and Talia Shire (credited as "Tally Coppola") in early roles. Country Joe McDonald makes an appearance, as spokesman "AM Radio". In Dallas, at the Southern Methodist University, news comes in about a gas