Summary:
- During World War II, battleships and submarines carried echo sounders.
- The sound waves bounce off the nearest object and then return to the ship.
- Scientists expected the seafloor to be flat and featureless.
- So they were shocked by what they saw: tremendous topographical features like mountain ranges, rifts, and trenches.
- These features helped scientists to discover the mechanism for continental drift.
- The map below is a modern map with data from several decades.
- The major features of the ocean basins and their colors on the map include: mid-ocean ridges, deep sea trenches, and abyssal plains.