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Origins of Ocean chap 1.ppt


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An Invitation to Marine Science





Tom Garrison


Key Ideas In Chapter 1

then testing the answers to those questions. The external world, not internal conviction, is the testing ground for scientific beliefs.

The objects comprising our solar system condensed about 5 billion years ago from a thin cloud that had been enriched by heavy elements made in exploding stars.

Earth is density stratified. During its formation heavy materials fell inward to form the core, and lighter substances rose to become the outer layers. Ocean and atmosphere are the least dense of these layers.

Earth first had a solid surface about 4.6 billion years ago. The ocean formed from clouds of steam and water vapor when Earth’s surface became cool enough to allow liquid water to rest on the surface.

Life probably arose on Earth shortly after its formation, about 4 billion years ago. Life may have arisen in the deep ocean.

Earth’s atmosphere has changed substantially through time. The most dramatic change began about 2 billion years ago when photosynthetic organisms began producing large quantities of oxygen.


© 2006 Brooks/Cole, a division of Thomson Learning, Inc.

Marine Scientists Use the Logic of

Science to Study the Ocean

Marine Science (or oceanography) integrates many different

types of science:

• Marine geology – the study of Earth’s crust and composition.

• Physical oceanography – the study of waves, currents, and climate prediction.

• Marine biology – the study of the nature and distribution of marine organisms.

• Chemical Oceanography – the study of the dissolved gases and solids in the ocean.


The Scientific Method


Fig. 1-5, p. 6 Curiosity

A question arises about an event or situation: Why and how does this happen? Why are things this way?

Stepped Art


Patterns emerge. If one or more of the relationships hold, the hypothesis becomes a theory, an explanation for the observations that is accepted by most researchers.


Tests are undertaken in nature or in the laboratory. These tests permit manipulating and controlling the conditions under which observations are made.


A tentative explanation is proposed. Controlled experiments are planned to prove or disprove potential

cause-and-effect relationships. A good hypothesis can predict future

occurrences under similar circumstances.

Observations, measurements Our senses are brought to bear: What is happening? Under what circumstances? When? How does it operate? Does there appear to be a dependable cause-and-effect relationship at work?


Laws describe events in nature that occur with unvarying


Earth Was Formed of Material

Made in Stars

What do we know about the origin of the Universe?

The Big Bang is the term used to describe the beginning of the

universe, probably about 14 billion years ago. As the universe expanded, it cooled, eventually allowing the formation of

atoms, which then formed galaxies and stars.

What do stars have to do with the ocean?

Most of the substance of Earth, its ocean, and all living things, was


© 2006 Brooks/Cole, a division of Thomson Learning, Inc.

Stars and Planets and Contained

within Galaxies

What do stars have to do with the ocean?

Most of the substance of Earth, its ocean, and all living things, was

formed by stars. Every chemical element heavier than hydrogen was

manufactured and released into space by stars.


Stars Make Heavy Elements from

Lighter Ones

The origin of a solar system in

the spiral arm of a galaxy. Our

sun and its family of planets


© 2006 Brooks/Cole, a division of Thomson Learning, Inc.

Earth, Ocean, and Atmosphere Accumulated

in Layers Sorted by Density

How did Earth become density stratified?

• Young Earth was probably homogeneous

• Heat and gravitational pressure caused Earth to partially melt

• Gravity then pulled the iron present into the center of Earth

• This heated Earth further


Earth, Ocean, and Atmosphere Accumulated

in Layers Sorted by Density

(top) The planet grew by the aggregation of particles.

Meteors and asteroids bombarded the surface,

heating the new planet and adding to its growing

mass. At the time, Earth was composed of a

homogeneous mixture of materials.

(middle) Earth lost volume because of gravitational

compression. High temperatures in the interior

turned the inner Earth into a semisolid mass;

dense iron (red drops) fell toward the center to

form the core, while less dense silicates move

outward. Friction generated by this movement

heated Earth even more.


© 2006 Brooks/Cole, a division of Thomson Learning, Inc.

Earth, Ocean, and Atmosphere Accumulated

in Layers Sorted by Density

How did water and water vapor form on early Earth?

The Sun stripped away Earth’s first atmosphere

Gases, including water vapor, released by the process of outgassing,

replaced the first atmosphere.

Water vapor in the atmosphere condensed into clouds.

After millions of years, the clouds cooled enough for water droplets to


Hot rain fell and boiled back into the clouds.


Earth, Ocean, and Atmosphere Accumulated

in Layers Sorted by Density


Earth Is an Ocean World

The relative amount of water in various locations on or near Earth’s surface. More than 97% of the water lies in the ocean. Of all water at Earth’s surface, ice on land contains about 1.7%,


Earth Is an Ocean World


© 2006 Brooks/Cole, a division of Thomson Learning, Inc.

Earth, Ocean, and Atmosphere

Accumulated in Layers Sorted by



Life Probably Originated in the Ocean

Fossil of a

bacteria-like organism (with an artist’s reconstruction) that photosynthesized and released

oxygen into the atmosphere.

Among the oldest fossils ever confirmed, this microscopic filament from northwestern Australia is about 3.5 billion years old.


© 2006 Brooks/Cole, a division of Thomson Learning, Inc.

What Will Be the Future of Earth?

How long can Earth exist?

• Our Sun will begin to die in 5 billion years.

• 6 billion years from now the sun will enter the red giant phase

and will engulf the inner planets.


© 2006 Brooks/Cole, a division of Thomson Learning, Inc.

Other Ocean Worlds

Where have scientists found evidence of water?

Europa – The gravitational pull of Jupiter twists Europa, cracking the ice crust

and warming the interior. In some areas the ice has broken into large pieces that have shifted away from one another but fit together like a jigsaw puzzle. This suggests the ice crust is lubricated by slush or water. A global ocean greater in volume than Earth’s ocean may lie beneath the movable crust. It may also be

salty - salinity has been detected by Galileo’s magnetometers.

Mars – Current models suggest that early in its history, Mars had a thick,

carbon-dioxide - rich atmosphere, much like the atmosphere of the early Earth. The atmosphere kept Mars warm and allowed water to flow freely, and an ocean may have existed on Mars about 3.2 billion years ago. Over the eons, rocks on the Martian surface absorbed the carbon dioxide and the atmosphere grew thin and cold. The ocean disappeared, most of its water binding to rocks or freezing beneath the planet’s surface.


Chapter Summary

In this chapter you learned that most of the atoms that make up Earth, its ocean, and its inhabitants were formed within stars billions of years ago. Stars spend their lives changing hydrogen and helium into heavier elements. As they die, some stars eject the elements into space during cataclysmic explosions. The sun and planets,

including Earth, condensed from a cloud of dust and gas enriched by the recycled remnants of exploded stars.

Earth formed by accretion – the clumping of small particles into a large mass. The mass heated as it grew and eventually melted. The heavy iron and nickel crashed toward Earth’s center to become its core; the lighter silicates and aluminum compounds rose

to the surface to form a crust. Earth became density stratified – that is layered by


The ocean formed as soon as Earth was cool enough for water to remain liquid. Life followed soon thereafter.


Fig. 1-5, p. 6


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