Layers of the Earth September 10, 2009
Rationale • In order to understand how ocean basins and continents formed (and more importantly, how they change), we must understand the processes that created them. • Thus, we must come to understand the processes that created the earth.
In the VERY beginning… • There was no space. • There was no time. • There was no space-time. • There was NOTHING. • …. • All of a sudden, BANG!
The Big Bang • The theoretical “singularity” that was our infinitesimally small universe exploded into being around 15 billion years ago. • Everything that the universe contains in it was somehow compressed into a dot with infinite density and expanded into everything we now know. • Basic elements like hydrogen and helium began to permeate and define space
10 ½ Billion Years Later… • Particles of cosmic dust begin to coalesce due to gravity. • Eventually larger chunks of collected dust attract the smaller ones • The mass became so large that the gravitational pull it possessed caused the particles it was made of to experience massive friction • The friction, coupled with radioactive decay caused the mass to become extremely hot, on the order of millions of degrees at its center. • Eventually, the heat at the core became so hot that hydrogen atoms began to fuse together to form deuterium, tritium, and helium. • This fusion reaction ignited the mass into what we now see as the sun.
Meanwhile… • In the surrounding area, more clumps of dust are gaining mass, though none get large enough to start a fusion reaction. • Five of them are mostly made of heavy metal, and collect inwards close to the sun, while four are mostly made of gas and become more massive, yet spread out beyond the metal masses
Earth • The earth gained considerable mass, enough to mimic the sun in its formation as heavy friction and radiation induced astronomically-high temperatures. • The heat was enough to liquefy the iron, nickel, and silicates that it contained. • Fortunately, the heat energy reached nowhere near enough to spark a fusion reaction
Proto-Earth • Earth as it began was a large ball of molten rock and metal. • No life existed, or could exist on earth at this point. • Panspermia: belief that all life components began and spread with the Big Bang • In the next few million years, the earth would begin to cool and the molten rock would solidify.
Proto-Earth (cont.) • The heavy core of dense iron and nickel became solid at its center due to the immense pressure surrounding it. • Most of the rock that makes up our planet remains molten to this day, with the top-most ~30km cooling and hardened as rocks/soil.