A passive margin is the transition between oceanic and continental lithosphere that is not an active plate margin. A passive margin forms by sedimentation above an ancient rift, now marked by transitional lithosphere. Continental rifting forms new ocean basins. Eventually the continental rift forms a mid-ocean ridge and the locus of extension moves away from the continent-ocean boundary. The transition between the continental and oceanic lithosphere that was originally formed by rifting is known as a passive margin.
Rifting-to-spreading transition
Passive continental margin
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about 85,133,000 km2 (32,870,000 sq mi). It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for separating the New World of the Americas from the Old World of Afro-Eurasia.
As the Gulf Stream meanders across the North Atlantic from the North American east coast to Western Europe its temperature drops by 20 °C (36 °F).
Path of the thermohaline circulation. Purple paths represent deep-water currents, while blue paths represent surface currents.
Sargassum fish (Histrio histrio)
Iceberg A22A in the South Atlantic Ocean
