Data collected by the drilling ship Glomar Challenger confirmed that none of the ocean floor is more than about 180 million years old.
Glomar Challenger began drilling on both sides of the mid-ocean ridges to gather data. The data confirmed what the sea-floor spreading hypothesis predicted. The ocean floor is youngest along the central valley of the mid-ocean ridge while the ocean floor in subduction zones or near the edges of the continents is oldest. The data has confirmed that none of the ocean floor is more than 180 million years old because the older oceanic rock will undergo subduction and go back to the earth's mantle.
