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, 0-

40 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