BIOL 1001 Lecture : Lecture Topic 7
Document Summary
Chapter 11: the hadean & archaen eons of precmbrian time. Precambrian (proterozoic, archaen, and hadean eons) = inconspicuous fossils. Anything that is more recent than precambrian is considered conspicuous. + less than 20% of rocks at earth"s surface are of precambrian age. Hadean = eon between the formation of the solar system and the formation of the first rocks on earth. The origin of the solar system from a solar nebula: spherical young nebula rotates slowly, condenses, rotates faster, contracts to a disk, rings of materials separated from the sun, materials in the rings condense to form planets. *all planets including earth formed within a short period of time. Water erosion + tectonics on earth = no rocks found as old as earth. + proxy for the age of planetary material in the solar system. The newborn earth was very hot due to: Strong radioactive decay, therefore: homogenous, molten earth. Less dense silicates float to surface, termed a magma ocean.
