Oceanography 100
P Anderson
Chapter one outline
Geography of the oceans
Earth’s oceans:
• Cover 70.8% of Earth’s surface
• Are interconnected (“world ocean”)
• Have huge size and volume (as a reservoir, contain 97% of Earth’s water)
The four principal oceans
• Pacific
• Atlantic
• Indian
• Arctic
• Plus:
• Southern or Antarctic Ocean
Comparing oceans to the continents
Comparing depth of the oceans to elevation on land
Early exploration of the oceans
• Pacific navigators peopled many remote islands
Early exploration of the oceans
• Advancements of European navigators
– Phoenicians explored the Mediterranean Sea and beyond
– Pytheas developed method to determine latitude
– Eratosthenes calculated circumference of Earth
– Ptolemy produced map that shows known land surrounded by largely unexplored
oceans
Early exploration of the oceans
• The Vikings explored the North Atlantic and established many colonies
Early exploration of the oceans
• During the Age of Discovery, Columbus and Magellan make journeys of exploration
Early exploration of the oceans
• Voyaging for science began with English navigator and explorer Captain James Cook
– Mapped many unknown islands
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Determined outline of the Pacific Ocean
Sampled ocean properties
Modified shipboard diet to eliminate scurvy
Used John Harrison’s chronometer to determine longitude
The scientific method
Origin of the Solar System and Earth
• Cloud of gas and space dust (nebula) began to contract about 4.6 billion years ago
Origin of the Solar System and Earth
• Protoplanets were created from the nebula
• Protoearth was initially homogenous:
– Larger in size than today’s Earth
– Had lots of volcanic activity
– No continents or oceans
– No life
Density stratification
• Protoearth experiences density stratification
– Density = how heavy something is for its size
– Density stratification causes high density material to sink while low density
material rises
• High density material = rock material and metals
• Low density material = gases
Density stratification creates a layered Earth
Origin of the oceans
• As a result of density stratification, water for the oceans is outgassed from inside
Earth
Origin of the atmosphere
• Density stratification caused Earth’s early atmosphere (water vapor and carbon
dioxide) to be outgassed from inside Earth
• The initial atmosphere was rich in hydrogen and helium
• Earth’s present atmosphere is rich in nitrogen and oxygen
Photosynthesis releases oxygen to the atmosphere
Origin of life on Earth
• Stanley Miller’s experiment simulating conditions of an early Earth showed that life
probably began in the oceans
Major events in Earth’s development