Transcript The 4 Earth Sciences

The 4 Earth Sciences
Unique Earth
(The blue dot)
• Earth formed with the birth of our solar
system, 4.6 billion years ago.
– That’s 4,600,000,000 years ago!
• 71% of the surface is covered with water
• Due to the Earth’s rotation it is an oblate
spheroid.
– The spinning creates a bulge at the equator
– Circumference around the poles = 40,007km
– Circumference around the equator = 40,074km
• Crust – the outer, hardest layer of the earth;
• continental crust (mostly granite, 2.7 g/cm³, 040 km)
• oceanic crust (basalt 3.0 g/cm³, 0-10km)
• Mohorovic Discontinuity (Moho) –
the lower boundary of the Earth’s crust
and the mantle
• averaging 8 kilometers (5 miles) in depth under
the oceans
• 32 kilometers (20 miles) in depth under the
continents
• Mantle – molten rock, beneath the
crust, more dense than the crust
• average density 3.3 – 5.5 g/cm³, and
• Thickest layer of the earth = 2,900km
• Separated into 3 structural zones
• Lithosphere – crust and upper most,
solid, rigid portion of the mantle –
broken into pieces (0-100 km)
• Asthenosphere – partially molten
rock in the upper mantle; plastic
consistency (100-700km)
• Mesosphere - below the asthenosphere,
the solid mantle rock
• Outer Core – liquid iron and nickel
(9.9 – 12.1 g/cm³, 2900 to 4980km)
• Inner Core – solid, iron and nickel
(12.7-13.0 g/cm³, 4980 to 6370km)
• So…. Why are we studying
Earth Science???
• Geology –
• Study of the Earth’s surface and interior
• Meteorology –
• Study of the Earth’s atmosphere, weather
• Astronomy –
• Study of all celestial bodies outside of our
planet
Oceanography –
• Study of the Earth’s oceans
Origin of the Universe
• Big Bang Theory – the universe began
(10 to 15 billion years ago-bya) to expand
with the explosion of concentrated matter
and energy and has been expanding ever
since.
• The further out in the universe – the faster
matter is moving
Origin of the Solar system
• About 5 bya, a cloud of gas and dust 10
billion km in diameter rotated slowly in
space.
• 500 million years (1/2 billion) of gravity,
this cloud began to shrink and therefore
spin faster.
• The inner material was so hot that nuclear
fusion began, creating our sun
Origin of the Solar system
• 10% of the cloud remained to form a
surrounding disk
• Friction, electromagnetism, and gravity
within the disk caused most of this mass to
collect into smaller masses and form
protoplanets – Protoplanet hypothesis
Origin of the Earth
• Earth is thought to have been entirely
molten; as the heavier metals, iron and
nickel, sank to the center forming the
dense core.
• The molten earth was separated into
layers (density stratification) – the more
dense materials toward the center; less
dense toward the surface.
Origin of the Earth
• During this separation, trapped gases and steam
were released to the surface through volcanic
eruptions
• These expelled gases created our atmosphere
• The steam condensed into water to slowly form
the oceans.
• The continents formed from huge lava flows
from volcanoes over millions and millions of
years
Structure of the Earth
• Inner core – 1200 km diameter, solid iron and
nickel
• Outer core – 2250 km thick, liquid iron and nickel
• Mantle – 2900 km thick, iron, magnesium, silicon
• Crust – 10 to 65 km thick, mostly (74.3%)
oxygen & silicon
Got to know
• Fact: unchanging things that are true or
real & based on many observations
• Law: a description of a relationship
between events that occur together
repeatedly
• Theory: an explanation that has been
partially verified