Unveiling Earth’s Layers: A Dive into Geology

1. The 4 Earth Sciences

2. 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

3. 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

4. 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)

5. 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)

7. So…. Why are we studying Earth Science???

8. Geology – • Study of the Earth’s surface and interior

9. Meteorology – • Study of the Earth’s atmosphere, weather

10. Astronomy – • Study of all celestial bodies outside of our planet

11. Oceanography – • Study of the Earth’s oceans

12. 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

13. 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

14. 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

15. 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.

16. 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

18. 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

19. 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