ASTRO-110 Lecture Notes - Lecture 8: Proterozoic, Archean, Volcanism
22 Sep 2020
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First into 4 eons: hadean, archean, proterozoic and phanerozoic. Phanerozoic means visible life present to 542 million years ago. Proterozoic means early life 542 million 2. 5 billion years ago. Hadean hellish conditions 2. 85 start. Oceans and continents already formed in first 100 million years. From eons to eras to periods to epochs to ages. Marked by specific changed to earth not by predetermined duration. To study the age of the earth we look at tiny mineral grains of zirconium silicate (zircons) Zircons solidified about 4. 38 billion years ago. The oldest age that earth can possibly be determined by the age of our solar. Places it at almost 4. 4 billion years. Geological time scale-distinct intervals in earth"s history system by looking at meteorites. The moon is around 4. 5 billion years old. Earth"s atmosphere was created through comets and planetesimals from deep space that contained ice and gaseous content not found near the sun volcanoes volcanoes.
