Wanderlust World Wanderlust World The North Atlantic Ocean basin is younger than the Pacific—by about 20 million years. While the Pacific basin dates back roughly 200 million years, the North Atlantic didn't fully open until approximately 180 million years ago, during the Early Jurassic period.
The breakup of Pangaea began around 200 million years ago as the North American and Eurasian plates started separating. Rifting initiated in the Central Atlantic, but the northern segment—between Greenland and Eurasia—lagged behind. Seafloor spreading in the North Atlantic proper commenced around 180 million years ago, creating new oceanic crust that continues forming today at the Mid-Atlantic Ridge.
The Pacific basin sits atop the Pacific Plate, Earth's largest tectonic plate. Its oldest crust, found in the western Pacific near the Mariana Trench, dates to the Early Jurassic (~190-200 Ma). But the basin's history stretches further: its predecessor, Panthalassa, covered much of the planet during the Paleozoic. The Pacific has been shrinking ever since the Atlantic began opening, consumed by subduction zones along the Ring of Fire.
Basin age shapes everything from seafloor topography to mineral deposits to biological evolution. The younger North Atlantic has simpler bathymetry—broad abyssal plains, a prominent mid-ocean ridge, fewer seamounts. The older Pacific hosts the deepest trenches, oldest seamount chains, and most complex plate boundaries. Both basins continue evolving: the Atlantic widens ~2.5 cm/year; the Pacific narrows.