Maarg Manthan · Topic 10.4

The Atlantic Ocean

Geography › Ocean Relief, Oceans and Seas · Topic 10.4

The Atlantic Ocean is the second largest ocean, covering about 106 million square kilometres, S-shaped and lying between the Americas and Europe-Africa. Its central Mid-Atlantic Ridge divides it into two basins. It has an irregular coastline with many seas, a wide shelf, the Gulf Stream system, the Grand Banks fisheries and the busiest ocean trade routes in the world.

6 min read · UPSC Prelims · Geography · Ocean Relief, Oceans and Seas

At a Glance

Area About 106 million sq km
Shape S-shaped, narrow compared with length
Central feature Mid-Atlantic Ridge
Deepest point Puerto Rico Trench, about 8,400 m
Key current system Gulf Stream and North Atlantic Drift
Exam link UPSC Prelims, Geography: Ocean Relief, Oceans and Seas

Where Does It Fit?

This is the fourth topic of the category on ocean relief, oceans and seas. The previous topic described the Pacific, and this one covers the Atlantic, the second largest ocean. The next topic describes the Indian Ocean. Previous topic: The Pacific Ocean. Next topic: The Indian Ocean.

What Are the Extent and Shape of the Atlantic?

In short: the Atlantic is a long, S-shaped ocean with an irregular coast, sliced down the middle by a ridge.

The Atlantic Ocean covers about 106 million square kilometres, or around one-fifth of the Earth’s surface, and is the second largest ocean after the Pacific. It is shaped like an S, stretching from the Arctic to the Southern Ocean, and is narrow compared with its length: it is about 2,900 km wide between Brazil and West Africa at its narrowest point. The name comes from the Greek Atlas, the Titan who held up the sky. The coastline on both sides is highly irregular, with many bays, gulfs and marginal seas, and the ocean receives the water of many of the world’s great rivers, such as the Amazon, Congo, Mississippi, St Lawrence and Orinoco. Although many rivers drain into it, it is the saltiest of the major oceans on average, because of strong evaporation in the subtropics. The matching coastlines of South America and Africa inspired the theory of continental drift, as in Continental Drift Theory of Alfred Wegener, and the Atlantic is still widening by a few centimetres every year.

What Are the Relief Features and Islands of the Atlantic?

Feature	Description
Mid-Atlantic Ridge	A long, S-shaped ridge running along the centre for about 16,000 km, parallel to the coasts; a divergent plate boundary at which new crust forms, as in Minor Ocean Relief Features; Iceland, the Azores, Ascension, St Helena and Tristan da Cunha are its peaks
Basins	The ridge divides the Atlantic into eastern and western basins; transverse ridges such as the Walvis Ridge and the Rio Grande Rise cut across the south
Trenches	Fewer than in the Pacific: the Puerto Rico Trench, about 8,400 m, is the deepest; others are the South Sandwich Trench and the Romanche Trench
Continental shelf	Wide in the north, near Newfoundland, the North Sea and the British Isles; the Grand Banks are shallow, fish-rich platforms
Islands	Britain and Ireland, Iceland, Newfoundland, the Canaries, Cape Verde, the Azores, Bermuda, the West Indies and the Falklands

The Sargasso Sea is a unique area within the North Atlantic gyre, east of the Bahamas and around Bermuda, defined by currents and not by coasts. It is covered with floating Sargassum seaweed, is calm and warm, and has a high salinity. It is the breeding ground of the European and American eels.

What Are the Seas and Currents of the Atlantic?

Seas and gulfs: the Caribbean Sea, the Gulf of Mexico, the Mediterranean (with the Black Sea), the North Sea, the Baltic Sea, the Norwegian Sea, the Labrador Sea, Hudson Bay and the Gulf of Guinea, as in Marginal Seas.
North Atlantic currents: the warm North Equatorial Current feeds the Gulf Stream, which flows north along the United States coast and becomes the North Atlantic Drift, which makes northwestern Europe warmer than other places at the same latitude. The cold Labrador Current flows south from the Arctic, and the cold Canary Current flows along northwest Africa.
South Atlantic currents: the warm Brazil Current and the cold Benguela Current off southwest Africa, which creates the Namib desert, and the cold Falkland Current, as in Pacific and Atlantic Ocean Currents.
Grand Banks: where the warm Gulf Stream meets the cold Labrador Current off Newfoundland, plankton flourish and fog is frequent. It was one of the greatest fishing grounds, but overfishing led Canada to close the cod fishery in 1992.
Hurricanes: the Atlantic hurricane season runs from June to November, and the storms hit the Caribbean and the southeastern United States, as in Path, Intensity Scale and Breeding Grounds of Tropical Cyclones.

Why Does the Atlantic Matter, and What Is Happening to Its Circulation?

The Atlantic has the busiest sea routes in the world, joining the industrial regions of North America and Europe, and it is linked to the Mediterranean and the Indian Ocean through the Strait of Gibraltar and the Suez Canal, and to the Pacific by the Panama Canal. It was the centre of the slave trade and of European colonial expansion, and is the home of NATO. It also has large offshore oil and gas fields in the North Sea, the Gulf of Mexico, Brazil and West Africa.

The most important climate question is the Atlantic Meridional Overturning Circulation, AMOC, the large circulation that brings warm surface water north and sends cold, dense water south in the deep. Together with the Gulf Stream, it carries heat to northwestern Europe. The IPCC concluded that the AMOC is very likely to weaken during the twenty-first century, with medium confidence that it will not collapse abruptly before 2100, but some recent studies suggest that the risk of a collapse is higher than previously thought, and the question remains under investigation. As an analytical point, a weaker AMOC would cool the North Atlantic region, raise the sea level on the US east coast and shift tropical rain belts, which could affect the monsoon in the long run, so the Atlantic matters to India even though it has no coast there.

Why Is This Topic Important?

Facts Ridge, currents and Sargasso asked
Climate AMOC and Europe’s climate
Trade Busiest routes

What Came Next?

The next topic describes the Indian Ocean, which is the ocean most important for India. Next topic: The Indian Ocean.

Key People and Terms

Mid-Atlantic Ridge Divergent boundary in the centre
Gulf Stream Warm Atlantic current
Sargasso Sea Sea defined by currents with floating weed
Grand Banks Shallow fishing ground off Newfoundland
AMOC Atlantic overturning circulation
North Atlantic Drift Warm continuation of the Gulf Stream

Exam Corner

Points to Remember

The Atlantic is S-shaped.
Iceland sits on the Mid-Atlantic Ridge.
The deepest trench is Puerto Rico.
The Sargasso Sea has no coast.
The Grand Banks lie where warm and cold currents meet.

Do Not Confuse With

Gulf Stream and North Atlantic Drift Strong coastal current versus broad drift
Benguela and Brazil currents Cold versus warm
Atlantic and Pacific trenches Few versus many

Memory Hook

S-shaped with a ridge in the middle: warm Gulf Stream up, cold Labrador down, fish at the Banks.

Mains Angle

Questions link the Atlantic to climate and trade. These points add depth.

Tectonics Widening ocean
Climate Gulf Stream and AMOC
Fishery Grand Banks collapse

A Question You May Face

An original practice question, not a past paper question.

“Describe the relief and currents of the Atlantic Ocean and explain why the Gulf Stream is important to the climate of northwestern Europe.”

How to Answer

Shape S-shape and ridge.
Features Trenches and seas.
Currents Warm and cold.
Climate AMOC.

GS Relevance

Prelims: shape, Mid-Atlantic Ridge, seas, islands, currents, Sargasso Sea, Grand Banks. GS Paper 1: oceans and ocean currents.

Frequently Asked Questions

What is the shape of the Atlantic Ocean?

The Atlantic Ocean is S-shaped, long and narrow, stretching from the Arctic to the Southern Ocean between the Americas on the west and Europe and Africa on the east. It covers about 106 million square kilometres and is the second largest ocean in the world.

What is the Mid-Atlantic Ridge?

The Mid-Atlantic Ridge is an underwater mountain chain, about 16,000 kilometres long, running down the centre of the Atlantic Ocean, where the plates move apart and new crust forms. Iceland, the Azores and Ascension Island are parts of it that rise above the sea.

What is the Sargasso Sea?

The Sargasso Sea is a calm, warm and salty area of the North Atlantic surrounded by ocean currents, not by land, near Bermuda. It is covered with floating Sargassum seaweed, and is the breeding place of European and American eels.

Why is northwestern Europe warmer than other places at the same latitude?

The Gulf Stream and its extension, the North Atlantic Drift, carry warm water from the tropics to the North Atlantic, and the prevailing westerlies bring this warmth over northwestern Europe. This keeps its winters much milder than those of Canada or Siberia at the same latitude.

Why are the Grand Banks famous?

The Grand Banks off Newfoundland are shallow areas where the warm Gulf Stream meets the cold Labrador Current, causing rich plankton growth and fish stocks, particularly cod. They are also foggy, and Canada closed the cod fishery in 1992 after overfishing destroyed the stock.

PYQ Practice — Statement Analysis

1 Iceland lies on the Mid-Atlantic Ridge.

True

It is part of the ridge above sea level.

2 The Benguela Current is a warm current of the South Atlantic.

False

It is a cold current.

3 The Sargasso Sea is bounded by land on all sides.