time rock unit

A "time rock unit" is a concept in geology that refers to a specific section of rock that helps scientists understand the Earth's history and the age of various geological formations. When scientists study layers of rock, each layer often represents a different period in Earth's timeline. By examining the characteristics and fossil content of these layers, geologists can define time rock units, which serve as markers to trace the progress of geological and biological changes over millions of years. This approach helps create a clearer picture of Earth's past and its evolution over time.