Mapping of the Ocean Floor

In Geography Class 11: Mapping of the ocean floor, we’ll learn all about the ocean floor configuration and Hess’ seafloor spreading theory. After World War II, several expeditions to the ocean floor provided a detailed and better view of the inside of the ocean. Reports found that there are submerged mountain ranges and deep trenches located near the continent’s margins. 

A map is essentially defined as a proper and detailed visual representation of any specific area or part of an area that is visualised on an even and flat surface. There are various types of maps for representing various types of things. These things include an area’s physical features, political boundaries, topography, some roads, the population of an area, economic activities, natural resources present in the area, and climate changes. 

When it comes to maps, there are three different components that people should be aware of. Direction, Symbol, and Distance are the three components. The majority of the maps are then classified into various types. This classification is done based on origin, content, and scale.

Ocean Divisions Around the World

The world ocean is divided into five major sections. The following are the five ocean basins:

• Ocean of the Pacific

• The Atlantic Ocean

• The Indian Ocean

• The Arctic Ocean

• The Southern Ocean

Basin of the Pacific Ocean

More than half of the world’s free water is found in the Pacific Ocean. This demonstrates approximately 155 million square kilometres in the area. In comparison, the surface area of Alaska, Hawaii, and the continental United States is approximately 4 million square miles, or sixteen times less. The Pacific basin could accommodate all of the continents.

The key characteristics of the oldest existing ocean basin have been shaped by plate tectonic phenomena. The coastal shelf, which reaches depths of approximately 600 feet, is narrow along North and South America but relatively wide along Asia and Australia.

Under extreme pressure, continental plates fold into mountain ranges, while oceanic plates are pushed downward, forming deep trenches known as subduction zones. The stresses at these subduction zones are responsible for the volcanoes and earthquakes that have earned the Pacific basin the moniker “Ring of Fire.”

Basin of the Atlantic Ocean

The Atlantic Ocean, the second largest of Earth’s five oceans, is the most heavily travelled and studied, owing to its importance in ship traffic between Europe and North America. Atlas, one of Greek mythology’s Titans, inspired the name of this ocean.

The Atlantic Ocean covers approximately 20% of the Earth’s surface, covering approximately 75 million square kilometres. This includes the Black Sea, Baltic Sea, Caribbean Sea, Denmark Strait, and Davis Strait, as well as a portion of the Drake Passage, Mediterranean Sea, North Sea, Norwegian Sea, The Gulf of Mexico and nearly the entire Scotia Sea..

The Atlantic Ocean basin formed around 150 million years ago during the Jurassic period, when a rift opened up in the supercontinent of Gondwana, separating South America and Africa.

Basin of the Indian Ocean

The Indian Ocean, the third largest of Earth’s five oceans, is bounded on the west by Africa, on the east by Australia, and on the north by Asia and Australasian islands. It covers an area of 68 million square kilometres. There is no natural boundary between the Indian and Atlantic oceans, but a line approximately 4,020 kilometres long connecting Cape Agulhas at the southern end of Africa with Antarctica is commonly accepted as the boundary.

The Southern Ocean

Though not a true ocean basin, it stretches north from Antarctica’s coast to 60° South latitude, which coincides with the Antarctic Treaty Limit. The Southern Ocean has grown to become the fourth largest of the world’s five oceans. The Southern Ocean is unique in that it is a massive circumpolar body of water that completely surrounds the continent of Antarctica. It covers an area of 20 million square kilometres and includes the Amundsen Sea, the Bellingshausen Sea, the Ross Sea, the Weddell Sea, a small portion of the Scotia Sea, and a portion of the Drake Passage.

Basin of the Arctic Ocean

The Norwegian Sea, the North Sea, the North Polar Sea, and the Barents Sea are the smallest of Earth’s five ocean basins, with a total surface area of approximately 14 million square kilometres including major subdivisions.

The average depth of the Arctic Ocean is about 4,900 feet, and the deepest point is about 17,880 feet.

Ocean Floor Configuration

Continental Margins

Continental margins are the form located in the middle of the continental shores and deep-sea basins. 

In continental margins, continental shelf, continental slope, continental rise, and deep-sea ocean trenches also come under this division. 

Abyssal Plains 

Abyssal Plains are extensive plains. Abyssal Plains lie between the continental margins and mid-oceanic ridges. 

Abyssal Plains is where all kinds of continental sediment get deposited that moves beyond the continental margins. 

Mid-Oceanic Ranges 

Mid-Oceanic Ridges are an interconnected chain of mountain range systems living deep inside the ocean. 

Mid Oceanic Ridges are characterised by a central rift system at the crest, a fractionated plateau, and a flank zone all around its area. The rift system of these Mid-Oceanic Ridges is the zone of most and intense volcanic activity. 

Concept of Seafloor Spreading 

 The mapping of the ocean floor and different Paleomagnetic studies of rocks revealed many secrets of the ocean world. To understand the concept of seafloor spreading, let us first look at the ocean facts. 

1. In the Mid-Oceanic Ridge area, most of the volcanic activity happens there. It results in bringing a massive amount of lava to the surface in this area. 

2. There was a similarity in their formation period, chemical composition, and magnetic properties of the rocks equidistant on either side of the Mid Oceanic Ranges. 
3. A pattern was noticed in the age trends of rocks. The closer the rocks, the younger they will be. 

4. Studies found that rocks in the ocean crust are younger than the rocks found on the continental side. The oceanic crust rocks are around 200 million years old, whereas the continental rocks are more than 3,200 million years old. 

5. The deposited sediments layer on the ocean floor is thin. The sediment layer is almost 200 million years old. 

6. The deep trenches are a result of massive earthquake shocks in the Mid-Oceanic Ridges. The quake focus is revealed to have shallow depths. 

These facts laid a foundation for analysing the magnetic properties of the rocks on either side of the Mid-Oceanic Ridges. In 1931, Hess put-forwarded his hypothesis, popularly known as seafloor spreading. 

• He said that constant eruptions at the crest of the mid-oceanic ridges led to the rupture of oceanic crust. The new layer of lava pushes the oceanic crust of either side 
• The younger age of oceanic crust and the flourishing of one ocean doesn’t cause the other oceans to shrink. That is what Hess stated in his consumption of the ocean crust theory
• He also stated that the more the ocean floor gets pushed down because of the volcanic explosions near the crest, the more it sinks under the oceanic trenches and gets consumed

Conclusion 

The most obvious use of seafloor mapping is to assist ships in navigating their way around. Although most vessels travel at sea, they must be aware of hazards beneath the water, such as rocks and shallow banks where they could become stranded. It is even more critical for vessels that travel beneath the water, such as submarines, to have accurate maps in order to navigate and avoid hazards.