1. Chapter 15 - Oceanography

2. Modern Oceanography
The Challenger expedition investigated ocean currents, water temps, seafloor sediment, topography and marine life
This expedition used bottom dredges, nets, and other tools to get the data
The German ship the Meteor was the first to use sonar in the 1920’s

3. Advance Technology
The Topex/Poseidon satellite constantly monitors ocean surface temps, currents and wave conditions

4. Origins of the Oceans
There are geologic clues that indicate the oceans have been here since the beginning of geologic time
Approximately 4.6 billion years ago

5. Where did the water come from?
Scientists hypothesize the oceans came from 2 sources
When comets impact Earth, the impact releases water
The other is volcanism

6. Volcanism
During an eruption gases are released that are mainly composed of water vapor and carbon dioxide
Shortly after the formation of earth there was an episode of massive, violent volcanism
This released a lot of water vapor and carbon dioxide
As Earth’s crust cooled the water vapor condensed into the oceans

7. Comets
Comets are composed of ice and rock