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2B-1
Topic 2B:The Nature of Science
and Origins of the Ocean,Part II
Lecture:The Origin of Water & the Oceans
The Formation of Atoms, Molecules, the Earth, the Atmosphere, and the Oceans.
2B-4
○ Observation:the farther away from us a cluster of galaxies is,the faster it is moving away from us– in the past, galaxies were
closer to one another– at one time, were all together
(approximately 14 billion years ago)
Example: Origin of the Universe
What can science say about what happened before
the “Big Bang”?
Earth bathed in microwaves:
“echo” (TV static)
2B-5How do we know what stars and nebulae
are made of?
“Spectroscopy”
Every substance has a “light fingerprint:”it absorbs and emits
certain specific shades of each color
2B-6Gravitational attraction pulled togetherthe hydrogen and helium leftover from the Big Bang to create stars like the Sun
2B-7Nuclear Fusion inside Stars
○ Hydrogen and helium are the two smallest atoms.○ The enormous temperatures and pressures inside stars
cause small atoms to join (fuse) and become larger atoms.– Oxygen, carbon, silicon,
sodium, iron, and all the other large atoms are made from smaller atoms fusing together.
○ The fusion of small atoms into bigger ones releases a lot of energy. – This energy powers stars,
creating the light they send out.
2B-8
Planetary Nebula
Supernovae Remnants
Nebula
Clouds contain water, organic molecules, etc.
Stars explode in “Supernovae,”creating dusty clouds
2B-9Water in Our Solar System
CometsAsteroid
Saturn’sRings
Mars’Poles Europa
How is water on Earth different from water elsewhere?
Telescopes show us that water is quite common in the universe
Enceladus
Pluto is 33-50% ice.
2B-10
Formation of the Solar System & the Earth
Gravitational attractionpulls nebula together
Nebula
2B-13Where Did the Water in the Oceans Come From?
VolcanoesComets
Which hypothesis seems more likely based on the
observations that we have?
2B-14Why is the Ocean Salty?
Organisms’ BodiesBecome Sediments
Rivers Hydrothermal Vents
add salts(!)
remove salts
add some salts,remove other salts
2B-15The Fossil Record
○ Fossils are the remains of living things:bones, impressions (tracks, skin, feathers), dung, etc…
○ An incomplete & imperfect record of life in the past,so one must be careful when interpreting the fossil record
– new discoveries are constantly filling in gaps
– remains of some organisms are preserved more easily than others
If we find more fossils of shelled animals than “jellies”, should we conclude that there
were more shelled animals than “jellies?”
2B-17The Fossil Record IISpecific layers of the rocks contain specific fossils
Older rock is on the bottom
2B-18The History of Life on the Earth
First Appearance in the Rocks Age of Rocks
Winged Insects, Reptiles ≈ 300 million years ago
Seed plants, amphibians ≈ 350 million years ago
1st Life on Land ≈ 440 million years ago
Shelled organisms ≈ 540 million years ago
Multi-cellular Organisms ≈ 2.1 billion years ago
Single-Celled Organisms ≈ 3.4+ billion years ago
Order inferred from layers in sedimentary rocks. Time based on radiometric dating
(which also confirmed the order).
2B-19Earliest Life: Bacteria who lived in the ocean
Stromatolites
Fossils of Stromatolites
Oldest Fossils:3.5 billion years old
Fossilized Cyanobacteria
Stromatolite Fossils
Stromatolites in Australia Today
Earliest Life3.5+ billion years old
2B-20
AmmonitesEurypterid
Dorudon
Trilobite
Life started in the Ocean, and stayed there for most of the Earth’s History
Hallucigenia