Transcript Evolution of Earth - Valhalla High School

Evolution of Earth
Earth’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 protosun
• 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
• Early Earth
was a Forms
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