Oceanography: Exploring Earth's Final Wilderness

The early explorers of the ocean were interested in charting its islands, dimensions, and resources - and in using it as a highway for trade. Relive the exploits of these mariners, who included Europeans, Chinese, and Polynesians. Only later did scientific exploration of the ocean begin.

As recently as the 1950s, geologists envisioned the ocean basins as a submerged version of the continents. Explore the topography of the seabed, discovering that it is shaped by geological forces fundamentally different from those on land.

The ocean floor was once as mysterious as the surface of another planet. Investigate the technologies involved in measuring bathymetry, the undersea counterpart of topography. Weighted ropes and cables for gauging the depth of the sea have given way to sophisticated sonar from ships and radar from satellites.

Take a tour of organisms that live from the shallows to the ocean floor. Learn how to classify ocean zones, and discover the importance of temperature, chemistry, nutrients, light, and other factors for different life forms - from active swimmers to passive floaters and bottom dwellers.

What made the ocean floor the way it is? Trace the evidence that ocean basins are geologically young and that new oceanic crust is being continually formed at mid-ocean ridges, pushing and rifting continental plates in a process called plate tectonics.

Investigate subduction zones, where oceanic crust plunges beneath an overriding tectonic plate. These margins are associated with deep-sea trenches, earthquakes, tsunamis, and volcanoes. Examine other features, such as hotspots, which are a mid-plate phenomenon that includes the Hawaiian Islands chain.

Cover 9 billion years of cosmic history - from the big bang, to the accretion of the sun and planets, to the formation of Earth's oceans 4 billion years ago. The water in the oceans came from water vapor in volcanic eruptions and possibly from comet impacts.

Explore scenarios for the origin of life, which may have begun around deep-sea hot springs. The oceans have maintained roughly the same conditions over the entire history of life on Earth, even though the sea floor has renewed itself many times over through plate tectonics.

Ocean sediments are like tree rings that can be "read" as a history of the ocean and climate through time. Investigate the different sources of sediments, which range from products of erosion on land, to the remains of sea creatures, to ejecta from asteroid impacts.