The Atlantic Ocean is the second-largest ocean basin on Earth, covering approximately one-fifth of the planet’s surface. It separates the Americas from Europe and Africa, playing a substantial role in global weather patterns, trade, and history. The Atlantic basin contains unique geological and oceanographic features.
A Spreading Ocean Basin
The Atlantic Ocean is actively growing wider every year. This expansion is driven by seafloor spreading, which occurs along a geological feature running down the ocean’s center. Molten rock rises from the mantle to fill the gap created as tectonic plates move away from each other. This continuous volcanic activity forms new oceanic crust, slowly pushing the continents of North America, South America, Europe, and Africa farther apart. The rate of this continental drift averages about 2.5 centimeters (one inch) per year along the central ridge.
Home to the World’s Longest Mountain Range
The geological mechanism of seafloor spreading has created the planet’s most massive mountain chain, known as the Mid-Atlantic Ridge (MAR). This feature extends for approximately 10,000 miles (16,000 kilometers) from the Arctic to the Southern Ocean, marking the divergent boundary where the Earth’s tectonic plates separate. The MAR is mostly submerged, with its peaks rising about 1.8 miles above the surrounding seafloor. In a few rare locations, the mountains break the surface, forming islands like Iceland. Iceland sits directly atop the ridge, with parts resting on the North American plate and others on the Eurasian plate.
The Ocean Without Shores
Within the North Atlantic lies a region known as the Sargasso Sea, which is defined not by coastlines but by the currents that circle it. It is the only sea on Earth that lacks land boundaries. Instead, it is contained by the powerful clockwise flow of the North Atlantic Gyre, including the Gulf Stream to the west and the Canary Current to the east. The sea is named for the free-floating brown seaweed, Sargassum, which forms mats on the surface. This seaweed creates a unique pelagic ecosystem that serves as a nursery ground for many species of fish, sea turtles, and eels. The water within the gyre is notably calm and clear due to the lack of coastal sediment inflow.
The Massive Influence of the Gulf Stream
The Gulf Stream originates in the Gulf of Mexico and is responsible for transporting a tremendous volume of warm water northward through the Atlantic. This powerful current carries an amount of water that is estimated to be 60 to 90 times greater than the combined flow of all the world’s rivers. It flows along the eastern coast of North America before veering eastward across the ocean basin. The warm water carried by the Gulf Stream and its extension, the North Atlantic Current, releases heat into the atmosphere as it moves toward Europe. This heat transfer profoundly influences the climate of Western Europe, moderating temperatures and giving regions like the British Isles and Scandinavia much milder winters than other landmasses located at similar northern latitudes.