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The youngest Moon rocks are virtually as old as the oldest Earth rocks.

The earliest processes and events that probably affected both planetary bodies can now only be found on the Moon.

Moon rock ages range from about 3.2 billion years in the maria (dark, low basins) to nearly 4.6 billion years in the terrae (light, rugged highlands). Active geologic forces, including plate tectonics and erosion, continuously repave the oldest surfaces on Earth whereas old surfaces persist with little disturbance on the Moon.