Complex sentence: The Rock is said to be one of the oldest formations in the world; it is 3.8 million 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 formation in the world where the date is approximately put to 3.8 million years. Making it it as old as the rocks of Greenland and older than the Himalayas.