The age of oceanic rocks varies depending on their distance from the Mid-Atlantic Ridge, which is a divergent plate boundary where two tectonic plates are moving away from each other. The rocks that make up the crust on the oceans floor are youngest near the Mid-Atlantic Ridge and get progressively older as you move away from the divergent boundary in either direction, aging approximately 1 million years for every 20-40 km from the ridge. The oldest rocks in the Atlantic are about 180 million years old. Therefore, the ages of oceanic rocks far from the Mid-Atlantic Ridge are much older than those near it.