Evolution of EarthEarth’s Formation and Composition

College Environmental Science/Mrs. Cirillo

So How did it All Begin?

•Most generally accepted theory is the Big Bang

•All matter and energy was compacted into a single inconceivably dense point which then exploded outward creating our universe

•This occurred around 13.5 billion years ago

The Nebular Hypothesis

•Immanual Kant proposed that the planets and our sun formed from a giant rotating cloud of gas and dust known as nebulae

•Force of gravity contracted the cloud and in turn accelerated the rotation of the particles

•This fast spinning flattened the disc

The Sun Forms

•The early sun was known as the proto-sun

•It compressed under its own weight, and became dense and hot until the process of nuclear fusion began, allowing the sun to release some of the energy it produced as sunshine

The Planets Form•Planets formed as the solar nebula

cooled and condensed into sticky kilometer sized chunks called planetesimals

•The innerplanets formed as the denser less volatile material accreted together, leaving the gases and more voltile material to form the outer planets further away from the sun

Earth Forms•Early Earth was a molten mass

•As it cooled, a process known as differentiation transformed the mass into layers according to their density

•The most dense material formed the inside of earth or the core, and the less dense material formed the crust

•Earth is thought to be 4.53 billion years old

•Radioactivity and meteor impacts kept the earth hot

Earth’s Spheres Form

•The solid earth (continents and ocean floor) formed soon after earth differentiated, and goes through a constant cycle of growth and destruction throughout time

•The liquid and earth formed from escaping volcanic gases and comet ice

•The gaseous earth formed from escaping volcanic gases as well

Our Dynamic Earth

•Earth’s crust evolves and changed throught time by moving, eroding, melting, recrystallizing, crystallizing,and deforming

•These processes have lead to the formation of our natural resources and cycling of materials

So it is what it is…

•This means all the resources we have on the planet were created by this