Final answer:
The oldest rocks found on the ocean floor are around 160 million years old, but the Earth is 4.6 billion years old. This is because the processes of plate tectonics continually recycle and renew the ocean floor.
Step-by-step explanation:
The Earth is approximately 4.6 billion years old. The oldest rocks found on the ocean floor are around 160 million years old. This is because the processes of plate tectonics continually recycle and renew the ocean floor. New oceanic crust is continuously formed at mid-ocean ridges and old crust is subducted back into the Earth's mantle at deep-sea trenches.
As a result, the oceanic crust is younger than the continental crust, which can be several billion years old. The oldest rocks can be found on continents and areas with ancient crust that have not been subducted. So while the oldest rocks on the ocean floor are relatively young, the Earth's age is determined by the age of the oldest rocks on continents and the overall geological and fossil record.