Complex sentence: According to a NASA map of Martian surface ages, based on crater impact density, the area around Dinorwic is from before the end of Heavy Bombardment, which places its age in the Noachian epoch, around 3.8 billion years ago.
Split into simpler sentences: According to a NASA map of Martian surface ages, based on crater impact density, the area around Dinorwic is from before the end of Heavy Bombardment. This places its age in the Noachian epoch, around 3.8 billion years ago.