The continental slope is a submarine geological feature which connects the continental shelf to the abyssal plain, beginning at a depth of around 460 feet (140 meters). Together, the continental shelf and slope are often referred to as the “continental margin,” in a reference to the fact that the combined features are found at the margins of the Earth’s continent. The continental slope also happens to mark the boundary between the part of the world’s ocean scientists are familiar with and the mysteries of the deep sea.
To visualize the continental slope, it may help to think about the structure of the seafloor in general, starting with the shoreline of a continent. The land close to the shoreline is known as the continental shelf; the continental shelf is relatively uniform in depth and it is relatively easy to map and explore. At an amazingly uniform depth around the world, the slope of the continental shelf suddenly gets much steeper, turning into the continental slope. The depth at which the angle of the continental shelf changes is known as the shelf break.
As the continental slope plunges into the deeper parts of the ocean, conditions quickly change. The water becomes much colder and more sluggish. It is also totally devoid of life, and oxygen levels decline as well. As a result, the ocean life along this slope is markedly different than that found along the continental shelf, as it must be much more tolerant of extreme conditions. The deeper these animals live, the more intense the pressure gets; organisms from shallower depths, including humans, would literally start to implode from the pressure.
At the bottom of the continental slope, one finds the continental rise, a geologic feature which is created through the very slow accumulation of sediments. Beyond the continental rise lies the abyssal plain, the extremely flat and very deep ocean floor. The continental rise is often used as an indicator by ships, since it indicates that the continental shelf, and land, are close by.
The continental slope may be marked by deep valleys and folds in the ocean floor, caused by tectonic movement and underwater erosion from currents like those from major rivers. It is also studded with cold seeps, areas where gas escapes from the Earth’s crust. Scientific study of cold seeps has revealed an assortment of organisms which have adapted to their unique conditions, demonstrating that life will find a niche in any environment.