How old are rocks on earth?

4 billion years

Explanation:

Scientists have found the oldest known rocks on Earth. They are 4.28 billion years old, making them 250 million years more ancient than any previously discovered rocks. Earth formed about 4.6 billion years ago from a disk of gas and dust circling the sun.

4.28 billion years.

Explanation:

Making them 250 million years more ancient than any previously discovered rocks.