The continental shelf is a large, undersea edge to each continent. The areas where the sea is shallow because of the presence of a continental shelf is called a gulf, and though they are underwater at the moment, during glacial periods in the planet’s history they were exposed due to the low sea levels at the time. These continental shelves are considered to be the property of the countries they border, though they are obviously uninhabitable.
The width of the continental shelf can vary wildly depending on which continent it is attached to and its location. There are several areas which have very little in the way of continental shelf at all, while other places, such as the Arctic Siberian Shelf, are more than 930 miles across. The depth of the shelf can also vary widely, but generally speaking is not deeper than 490 feet. Technically these areas are not part of the wider ocean at all, but simply flooded parts of the continent.
There are three main geographical parts of a continental shelf that all have their own characteristics. These are the Inner Continental Shelf, the Mid Continental Shelf, and the Outer Continental Shelf. Each has its own specific biology and a specific geomorphology that relates both to the age of the stone and nearby volcanic activity under the surface of the sea.
The continental shelves are covered in a thick sediment from the gradual erosion of the continents into seawater. Most of it dates back to the last ice age, when only the deepest edges of the shelves were underwater. These shelves form a vibrant environment for marine life, who enjoy the comparatively warmer temperatures of the shallows and the presence of sunlight, unlike in the ocean’s deeps. Though life is prevalent on the shelves there are places where the conditions have become anoxic- lacking oxygen- which promotes the development of fossil fuels. Deep-sea drilling rigs are generally perched on the continental shelf, extracting oil from the sea floor.
There is also a slightly different definition of continental shelves. The physical shelves that line the continents are one, and the legal definition of continental shelves are another. Though some inhabited areas do not have any actual shelves to speak of, all countries have a legal provision for owning the distance of 200 nautical miles from their shore, providing this does not interfere with another country’s claim. Thus, even small islands can be said to have a continental shelf.