Complex sentence: The Rock is said to be one of the oldest formations in the world; it is 3.8 billion years old, making it as old as the rocks in Greenland and older than the Himalayas.
Split into simpler sentences: The Rock is said to be one of the oldest formations in the world. It is 3.8 billion years old, making it as old as the rocks in Greenland and older than the Himalayas.