Geography · Ch 18 — Water (Oceans)
Divisions of the Ocean Floors
Divisions of the Ocean Floors
The ocean floor is not a flat, featureless plain. It is a vast underwater landscape with its own mountains, valleys, and plains, just like the land above sea level. Geographers divide this submerged terrain into four major structural divisions, each with distinct characteristics. Beyond these four, the ocean floor also hosts a variety of other significant relief features that shape the underwater world.
The four major divisions of the ocean floor are the Continental Shelf, the Continental Slope, the Deep Sea Plain, and the Oceanic Deeps.
The Continental Shelf is the gently sloping, submerged extension of a continent. It is the shallowest part of the ocean, extending from the shoreline out to where the slope steepens dramatically. Because it is relatively shallow and receives sunlight, it is rich in marine life and is an important zone for fishing. It also often holds significant mineral and petroleum resources.
The Continental Slope is the steep, downward incline that connects the continental shelf to the deep ocean floor. This is where the true ocean basin begins. The slope marks a dramatic transition, dropping from the shallow shelf to the great depths of the ocean. Submarine canyons, which are deep, steep-sided valleys, are often found cutting into the continental slope.
The Deep Sea Plain is the vast, flat, and sediment-covered expanse of the ocean floor. These plains are among the flattest and smoothest surfaces on Earth, formed by the accumulation of fine sediments that have settled over millions of years. They cover a very large portion of the ocean floor and lie at great depths.
The Oceanic Deeps are the deepest parts of the ocean. These are long, narrow, and very deep trenches that are typically found at the edges of continents or island arcs. They are associated with tectonic plate boundaries, where one plate is forced beneath another. Oceanic deeps represent the greatest depths of the ocean and are far deeper than the surrounding deep sea plains.
The four major divisions are: Continental Shelf, Continental Slope, Deep Sea Plain, and Oceanic Deeps.
Beyond these four primary divisions, the ocean floor is also marked by several other major and minor relief features. These include:
- Ridges: Long, continuous chains of mountains that rise from the ocean floor, often running for thousands of kilometres.
- Hills: Smaller, isolated elevations on the ocean floor. …
The oceans are confined to the great depressions of the earth's outer layer. The oceans, unlike the continents, merge so naturally into one another that it is hard to demarcate them. The geographers have divided the oceanic part of the earth into five oceans, namely the Pacific, the Atlantic, the Indian, the Southern ocean and the Arctic. The various seas, bays, gulfs and other inlets are parts of these four large oceans.
A major portion of the ocean floor is found between 3-6 km below the sea level. The 'land' under the waters of the oceans, that is, the ocean floor, exhibits complex and varied features as those observed over the land. The floors of the oceans are rugged with the world's largest mountain ranges, deepest trenches and the largest plains. These features are formed, like those of the continents, by the factors of tectonic, volcanic and depositional processes. …