Simplify the following text for a Grade 7 native English-speaking person.
Original: It is the principal source of information about the absolute age of rocks and other geological features , including the age of the Earth itself , and can be used to date a wide range of natural and man-made materials .
Simplified: It is the main source of information about the age of rocks and other geological features , including the age of the Earth itself . It may be used to date a wide range of natural and man-made materials .