Chapter 14 – The Ocean Floor 14.1 The Vast World Ocean Text pp 394-400

The Blue Planet Nearly 71% of Earth’s surface is covered by the global ocean. Oceanography is the science that studies the global ocean, and draws on geology, chemistry, physics and biology.

Geography of the Oceans About 360 million square kilometers, or 71%, of all the surface of Earth is represented by oceans and smaller seas, such as the Caribbean Sea.

The world ocean can be divided into four main ocean basins – the Pacific Ocean… Largest ocean, and the largest single geographic feature on Earth. Covers half the ocean surface. World’s deepest ocean.

…the Atlantic Ocean… Half the size of the Pacific Ocean. Not quite as deep as the Pacific. Relatively narrow in width.

… the Indian Ocean… Slightly smaller than the Atlantic. Just as deep as the Atlantic. Located almost entirely in the Southern Hemisphere.

… and the Arctic Ocean. About 7% the size of the Pacific Ocean A little more than ¼ deep as the rest of the oceans.

Mapping the Ocean Floor The topography of the ocean floor is as diverse as that of the continents. We would see volcanoes, tall mountain ranges and large submarine plateaus if we could see to the bottom.

Bathymetry (bathos = depth, metry = measurement) is the measurement of ocean depths and the charting of the shape or topography of the ocean floor.

Today’s technology – particularly sonar, satellites, and submersibles – allows scientists to study the ocean floor in a more efficient and precise manner than ever before.

SONAR SONAR stands for… SOund NAvigation and Ranging SONAR works by transmitting sound waves toward the ocean bottom, and a receiver intercepts the echo reflected upwards.

Depth can be calculated from the speed of sound waves in water, and the time required from the energy pulse to reach the ocean floor and return. In this way a profile of the ocean floor is created.

Satellites Measuring the shape of the ocean floor from space is another recent technological breakthrough. Satellites can give us extremely accurate measurements, using microwaves instead of sound waves.

Submersibles A submersible is a small underwater craft used for deep-sea research. Submersibles are used to collect data about areas of the ocean that were previously unreachable by humans.

Today, many submersibles are unmanned and operated remotely by computers. These remotely operated vehicles (ROVs) can remain under water for long periods.