GEOL 2503 Introduction to Oceanography
Dr. David M. Bush
Department of Geosciences
University of West Georgia
Topic 3: The Water Planet
POWERPOINT SLIDE SHOW NOTES
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Topic 3: The Water Planet
Earth or Ocean?
Water on Earth’s surface
Don’t worry about the numbers, just know that the water on Earth is only a tiny fraction
of the volume of the entire planet.
Don’t worry about all the numbers, just compare them for reference
Here’s an important number. Oceans contain 96.5% of Earth’s water
Sphere depths
Sphere depth illustration
There really is only a single, global ocean. Continents are islands in that ocean. The size,
shape, position, and age of oceans changes as continents are rearranged over time
The water cycle, also known as the hydrologic cycle
The various places we find water are each referred to as reservoirs
Moving water between reservoirs
Residence time
Land and water on Earth’s surface
It is easy to see why the northern hemisphere is often referred to as the land
hemisphere, the southern hemisphere as the water hemisphere.
Disttribution of land and ocean by latitude. Graphical representation of slide 14.
Three main oceans
Maps of the three main oceans
Basic information about the Pacific Ocean
Pacific Ocean map. Note distribution of features on the ocean floor
The deepest spot in the world is the Challenger Deep in the Mariana Trench in the Pacific
Ocean near Guam. The Challenger Deep is deeper than Mount Everest is tall. A deep is a
geographical feature. It’s the deepest spot in any given ocean basin. In this case, the
Challenger Deep is not only the deepest spot in the Pacific Ocean, but also the deepest
spot in the world ocean.
Basic information about the Atlantic Ocean
Atlantic Ocean map.
Basic information about the Indian Ocean
Indian Ocean map. Note how different the shapes and the features of the three oceans
are.
The Arctic Ocean. The Arctic Ocean is really a sea in the Atlantic Ocean. A “sea” is a
semi-enclosed basin, part of a larger ocean.
The Arctic Ocean connects to the Pacific Ocean through the narrow Bering Strait (left
side between Alaska and Russia. The major opening is to the Atlantic between
Greenland and Europe. Still, most people consider the Arctic to be the fourth ocean.
A fifth ocean? The Southern ocean has Antarctica as a land boundary on the south. It’s
northern boundary is not land, it is marked by a change in ocean currents and
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characteristics.
Relative sizes of the five oceans
Geographic location of the five oceans
The hypsographic curve. Simply a graph of land elevation and water depth versus
surface area of Earth. Note the differences between land and seafloor.
Land elevation and water depth is the vertical axis. Percent of Earth’s surface is the
horizontal axis. Because 29% of Earth’s surface is land, the curve crosses zero (sea level)
at 29%. Note where the curve is steep, it means there is very little surface area over a
wide range of elevation or depth. Where the curve is flat, it means there is a lot of
surface area over a small range of elevation or depth.
Another way to look at the hypsographic curve. On the left, a bar graph where each bar
represents 1 kilometer of land elevation or water depth. On the right is essentially the
same curve in the previous slide. Here are given names of some major geographic
features. We’ll talk about those later.