Simplify the following text for a Grade 13 native English-speaking person.
Original: Although they have been deposited throughout the Phanerozoic , they are most commonly associated with rocks deposited during the Devonian , Permian and Triassic periods .
Simplified: Although they have been deposited throughout the Phanerozoic , they are most commonly associated with rocks deposited during the Permian and Triassic periods .