Ocean Floor Mapping| Class 11 Geography Notes

Ocean relief is caused due to Volcanic, depositional, tectonic, and erosional processes and their interactions. Ocean relief features are divided into Minor and Major relief features.

Ocean Floor Mapping is like creating a detailed picture of the underwater landscape revealing the mountains, valleys, plains, and other features that make it anything but flat.

In this article, You will learn about Ocean floor mapping, Ocean Relief features, Minor relief of the ocean, and the Significance of Oceanic Relief.

Ocean Floor Mapping| Class 11 Geography Notes

Ocean Relief Features

A major portion of the ocean floor mapping is found between 3 to 6 km below the average sea level. The land below the water of the oceans, the ocean floor reveals various and complex features compared to those observed above the land.

Ocean relief features are the underwater mountains, valleys, plains, and other features that shape the ocean floor. While the ocean floor might look smooth on a map it’s a world of dramatic variations in topography just like the landmasses above the water.

These features can be broadly categorized into major relief features and minor relief features.

• Major Relief Features: These are the large-scale structures that define the ocean floor.

Examples: Ocean Basins, Continental Shelves, Continental Slopes and Mid Ocean ridges.

• Minor Relief Features: These are the smaller variations that add detail to the ocean floor.

Example: Seamounts, Guyots, Trenches, Submarine Canyons and Atolls.

Minor Relief of the Ocean

Some of the minor relief features in the ocean floor mapping are as follows:

• Seamounts
• Mid-Oceanic Ridges
• Fracture Zone
• Guyots
• Trenches
• Ridges
• Hills
• Coral reefs
• Island Arcs
• Atolls
• Sleeps
• Canyons
• Submerged Volcanes
• Sea Scraps

Mid-Oceanic Ridges

• Massive underwater mountain ranges run along the centre of most ocean basins.
• Formed by seafloor spreading, where molten rock rises, cools, and pushes plates apart.
• Can reach the surface, forming islands like Iceland.
• The longest mountain range on Earth, stretching for tens of thousands of kilometres.
• Home to unique ecosystems due to hydrothermal vents spewing minerals and heat.

Atolls

• Ring-shaped coral reefs or islands surrounding a lagoon.
• Form on top of submerged volcanoes that slowly sink over millions of years.
• As the volcano sinks, coral reefs continue to grow upwards, creating a ring-shaped island with a central lagoon.
• Found in warm, shallow tropical waters.
• Important for marine biodiversity and tourism.

Seamount

• Isolated underwater mountains that don’t reach the water’s surface.
• Formed by volcanic eruptions on the ocean floor.
• Very common, with estimates suggesting hundreds of thousands exist.
• Can provide stepping stones for migrating animals and influence ocean currents.
• Some seamounts eventually erode into flat-topped guyots.

Submarine Canyons

• Deep, V-shaped valleys cut into the continental slope.
• Similar to canyons on land.
• Believed to be formed by turbidity currents, underwater avalanches of dense sediment.
• Can channel sediment down to the deep ocean floor.
• Important pathways for transporting nutrients and organic matter.

Guyots

• Flat-topped seamounts are believed to be eroded versions of seamounts.
• Formed when a seamount’s peak breaks the ocean surface for a long time, waves and currents erode the top into a flat plateau.
• As the tectonic plate the guyot rests upon moves, it slowly sinks keeping the flat top even as it descends deeper.
• Can provide evidence of past sea levels and plate movements.

Reefs

• Ridge-like underwater structures are formed by the deposit of calcium carbonate from living organisms.
• Two main types of Reefs are as follows:
  1. Coral Reefs: Built by coral polyps, which are tiny marine animals that extract minerals from seawater to build hard skeletons.
  2. Oyster Reefs: Built by the shells of oysters and other shellfish.
• Provide critical habitat for a variety of marine life.
• Protect coastlines from erosion.
• Sensitive to pollution, climate change, and overfishing.

Significance of Study of Oceanic Relief

• Safe navigation: Ships and submarines need to know the underwater landscape to navigate safely. Charts that map ocean relief are essential for safe travel.

• Marine life: Different ocean depths and features provide habitats for various marine creatures. Studying relief helps us understand these habitats and the life they support.

• Seafloor resources: Features like underwater mountains and trenches can hold valuable resources like minerals and oil. Knowing where these features are helps us locate these resources.

• Ocean currents: The bumps and valleys of the ocean floor influence how water moves around in currents. Understanding these features helps us predict ocean circulation patterns.

• Marine life: Different ocean depths and features provide habitats for various marine creatures. Studying relief helps us understand these habitats and the life they support.

Conclusion

Mapping the entire ocean floor is a massive undertaking, and there’s still a lot of unexplored territory out there. However new technologies and international efforts are constantly working to create a more complete picture of this hidden world.

Ocean mapping can be done by various methods some of them are by sending sound waves in the depths of the ocean like SONAR, by using satellites to make detailed analyses of weather and by using underwater machines, and robots to explore the ocean closely.

Class 11 Ocean Floor Mapping – FAQs

What do you mean by mapping of ocean floor?

Mapping the ocean floor is like creating a detailed picture of the underwater landscape, revealing the mountains, valleys, plains and other features that make it anything but flat. It’s like taking a giant map of the world and adding all the hidden details that are usually covered by water.

What is the ocean floor configuration?

Ocean Floor Configuration – On the basis of depth and relief, the ocean floor is divided into three main parts. These are: Continental Margins – These include continental shelf, continental slope, continental rise and deep oceanic trenches. These form the transition between continental shores and deep sea basins.

What are 2 methods used in mapping the ocean floor?

Early single-beam sonar systems, called fathometers, were used to measure the seafloor depth beneath a ship. In the 1960s, multibeam sonar systems were developed to measure a larger area using many beams of sound in a fan-shaped pattern. Multibeam sonar can map much broader areas than single-beam sonar.

What are the 4 types of ocean floor?

The four types of ocean floor are The Continental Shelf , The Continental Slope , Abyssal Plains and Ocean Trenches .

What are the 4 benefits of mapping the ocean floor?

The four benefits of mapping the ocean floor are safe navigation in ocean , trade route , global supply chain and seafloor resources usecases.