Continents and Oceans are two of the major divisions on Earth. These include Asia, North America, South America, Antarctica, Europe and Australia.
Traditionally, continents were defined as large landmasses separated by natural barriers, mainly water. But this definition has become fuzzy over time.
Continents
The term continent is sometimes used to describe large landmasses that are separated from other parts of the world by an ocean. The seven most commonly recognized continents are Asia, Australia, Europe, Africa, North America, South America and Antarctica.
While it is generally understood that continents are discrete, landmasses ideally separated by expanses of water, the ideal criterion is often disregarded in favour of more arbitrary, historical conventions. For example, Iceland may be considered part of Europe while Madagascar is usually taken as a separate island in Africa.
In the context of geology, most of the continents are tectonic plates that float on a mantle layer (the asthenosphere) below Earth’s surface. Over time, these plates move away from each other, separating along rift valleys and moving into new ocean basins.
Oceans
The oceans are a huge reservoir of salt water on Earth that covers 71% of the planet. They are the world’s largest ecosystem and support a vast variety of marine life.
However, they are threatened by many human-related issues, such as overfishing and pollution, which can cause deterioration of marine habitats. It’s essential for the survival of marine life that the world’s oceans remain healthy and resilient to climate change.
Scientists divide the ocean into several zones based on physical and biological conditions. They include the pelagic zone, which encompasses the open water column; the upper sunlit zone; and the cold dark sea floor, where the deepest parts of the ocean are located.
Plate tectonics
Plate tectonics is the unifying theory of geology that explains the movement of Earth’s surface. It is based on the idea that Earth’s outer layer (lithosphere) is divided into several slabs of rock, called plates. These plates glide over an underlying, partially molten layer of rock known as the asthenosphere.
Tectonic plates contain a mixture of oceanic crust, which is formed at sea-floor spreading centers, and continental crust, which is formed through subduction beneath continents and arc volcanism. Most of the lithosphere is about 100 km thick, but its thickness varies according to its age and composition.
Tectonic plates move constantly to reshape the planet’s landscape. Over time, these movements translate into changes in the size and shape of ocean basins and the distribution of landmasses on Earth.
Geographical boundaries
Geographic boundaries divide and connect different areas of the world. They are the lines on maps that separate countries, states, provinces, counties, and cities.
Boundaries also help geographers identify spatial activity. For example, lines of latitude and longitude are used to identify the exact position of an area on a map.
Interaction between tectonic plates creates activity on their boundaries. Sometimes the plates spread apart, creating ocean trenches and eventually continents; other times, one plate slides under the other, creating volcanoes and earthquakes.
In this article, we will discuss the classification of geographical boundaries from a geo-ontological point of view by Smith and Galton. We will also show how these classifications might be modified by the influence of culture and beliefs.