How does the age of oceanic crust change farther from a spreading centre?

The age of oceanic crust increases as the distance from a spreading centre increases.12

This phenomenon occurs because new oceanic crust is continuously formed at the crests of oceanic ridges through the upwelling of magma. As this material cools, it is pushed laterally away from the ridge flanks, creating a record of progressively older seafloor.1342

This relationship is supported by several lines of geological evidence:
* Marine Sediments: The thickness and age of marine sediments increase with distance from the ridge crests.2
* Magnetic Anomalies: The ocean floor exhibits symmetrical bands of magnetic anomalies parallel to the ridge axis, which reflect the history of Earth's geomagnetic field reversals over time.35
* Ocean Depth: The depth of the ocean floor is proportional to the square root of the crustal age, as the crust undergoes thermal contraction and sinks as it moves away from the heat source at the spreading centre.4