The geographic time scale of earth is defined by time intervals. The largest unit of time is the supereon which is further divided into shorter interval intervals
Eon: Half a billion years or more and has more than 1 Era.
Era: Several hundred million years and has more than 1 period.
Period: has more than 1 epoch.
Epoch: Tens of million of years and has more than 1 age.
Age: Million of years
Precambrian period is the earliest period in earth's history. The next Eon is the Phanerozoic which is divided into Paleozoic, Mesozoic and Cenozoic Era.
Mesozoic Era has 3 periods Triassic, Jurassic and Cretaceous. It lasted 160 million years from Triassic period 230 million years ago thru the Jurassic period 200 million years ago and ended in the Cretaceous period 65.5 million years ago. China is one of the countries rich in dinosaurs fossil finds.
The next Era, Cenozoic Era, is also the start of the prehistoric China and Stone Age.
