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Why is oceanic crust much younger than continental crust?

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Earth's lithosphere and upper mantle — oceanic crust A cross section of Earth's outer layers, from the crust through the lower mantle.

Oceanic crust is significantly younger than continental crust because it is transient, being continuously created and destroyed as part of the global tectonic cycle.1

New oceanic crust is constantly generated at oceanic ridges through the process of seafloor spreading. As this crust moves away from the spreading centers, it cools and becomes increasingly dense. Eventually, this older, denser oceanic crust is consumed at subduction zones, where it sinks back into the Earth's mantle. Because of this constant recycling, the mean age of oceanic crust is only about 60 million years, and ocean floor rocks are generally less than 200 million years old.23451

In contrast, continental crust is much less dense and more buoyant, which prevents it from being easily subducted into the mantle. Consequently, continents are preserved over much longer periods, with the oldest continental rocks dating back more than 4 billion years.641