© 2016 Cengage Learning. All Rights Reserved. 1 Oceanography, An Invitation to Marine Science | 9e Tom Garrison The Origin of the Ocean

© 2016 Cengage Learning. All Rights Reserved.

1

Oceanography, An Invitation to Marine Science | 9eTom Garrison

The Origin of the Ocean


• Science is a systematic process of asking questions about the observable world by gathering and then studying information

• The universe’s observable mass consists mostly of hydrogen atoms– The heavy elements we see around us were

constructed in stars

• Earth is density stratified– Earth’s first solid surface formed about 4.6

billion years ago

Key Concepts


• Life probably originated in the ocean shortly after it formed

• Water, even liquid water, appears to be present in other places in our solar system

Key Concepts (cont’d.)


• Oceanography – story of the ocean

• Liquid water can exist on Earth

• Ocean – body of saline water

• Single world ocean – Earth’s oceans are connected

1.1 Earth Is an Ocean World


• Science – systematic process of asking questions, gathering and interpreting data

• Hypothesis – speculation that can be tested

• Experiment – test that simplifies observation in nature

• Theory – statement that explains observations

• Scientific method – process

1.2 Marine Scientists Use the Logic of Science to Study the Ocean


A Logical Series of Steps Can Represent the Procedure of Science


• The big bang occurred about 13.7 billion years ago

• Stars formed early in the history of the universe– About a million years after the big bang

temperatures were cool enough for atoms

– About a billion years after the big bang stars and galaxies could form

1.3 Stars Form Seas


• Stars and planets are contained within galaxies– We live in the Milky Way galaxy

– Stars – spheres of incandescent gases

– Star and family of planets – solar system

• Stars make heavy elements from lighter ones:– By fusing hydrogen into helium

– From dying stars – supernovae

Stars and Galaxies


The Dispersion of Heavy Elements


• Solar systems form by accretion– Particles clump together to form larger

masses

– Heavier elements are concentrated closer to the sun

– Lighter elements make up the outer planets

Solar Systems


• Density stratification – gravity pulls heavier elements towards the center of an object, lighter elements rise to the outside

• The first surface formed about 4.6 billion years ago

• Earth’s moon formed from a collision of Earth and another planetary body– About 4.4 billion years ago

1.4 Earth, Ocean, and Atmosphere Accumulated in Layers Sorted by Density


A Representation of the Formation of Earth

© 2016 Cengage Learning. All Rights Reserved.Stepped Art

Iron

Lightermatter andsilicates


• Earth’s first atmosphere was stripped away by radiation from the sun

• Vapors came from inside the planet – outgassing

• Water vapor existed in the atmosphere– Eventually cooled to form clouds and

precipitated to the surface

• Early ocean and atmosphere different from today

Earth’s First Atmosphere


• Biosynthesis – formation of living organisms from simple organic building blocks– Unlikely to occur today

– Conditions on the young Earth were sufficiently different

• Oldest fossils 3.4 to 3.5 billion years old– Remains of bacteria-like organisms

1.5 Life Probably Originated in the Ocean


One of the Oldest Fossils Ever Discovered


• The sun will begin to die in around 5 billion years– Red giant phase will engulf the inner planets

in solar atmosphere

– Earth will be recycled

1.6 What Will Be Earth’s Future?


• Water is not scarce in the solar system

• Jupiter and Mars contain ice

• Liquid water exists on Jupiter’s moons, Europa and Ganymede, underneath crusts of ice

• Liquid water could exist on Saturn’s moon Enceladus

1.7 Are There Other Ocean Worlds?


• Mars may have had an ocean in the distant past– Evidence for water erosion on the surface

– Water could have frozen beneath the surface as the planet lost its atmosphere

• Saturn’s moon, Titan, has a liquid ocean of hydrocarbons

• Water could exist on extrasolar planets

Is There Evidence of Water on Other Planets?


Evidence of a Once-Wet Mars


• We study our planet using the scientific method

• Atoms that make up Earth and the solar system were formed in stars

• Earth formed from accretion 4.6 billion years ago and became density stratified

• Life probably originated in the ocean

• No other planet in the solar system has a liquid ocean on the surface

Chapter In Perspective


• Could life have formed on other planets in our solar system?

• If so, would life on these planets resemble life on Earth?

Some Questions from Students

Documents

© 2016 Cengage Learning. All Rights Reserved. 1 Oceanography, An Invitation to Marine Science | 9e Tom Garrison The Origin of the Ocean