ESS261H1 Lecture Notes - Lecture 3: Mattress, Sticky Mat, Sexual Reproduction
Document Summary
Hot unstable surfaces of molten magma ocean w/ lack of water. Lacks life preservation due to unstable conditions (temperature, atmosphere) Alternative hypothesis: may have had intervals of time of cooling. Earth"s surface cooled quickly with oceans, nascent continents, opportunity for life. No known rocks have survived from the first 500 million years of earth"s history, but: studies of single zircons suggest that some continental curst formed as early as 4. 4 ga! Following hadean period (about 4 billion years ago) After earth has undergone: density differentiation (internal dynamo system established, initial cooling & surface stabilization, formation of liquid water at the surface & atmosphere generation. Prevailing conditions followed: high heat flow (internal radioactive isotope decay & continued impacting) This keeps initial crustal plates small with basaltic composition ( protocontinents : early atmosphere consists of; produced by outgassing/volcanism. H2o vapor: duller sun of ~30% less luminous than present, early oceans formed, crustal development.
