Respuesta :
The geologic time scale was developed after scientists observed changes in the fossils going from oldest to youngest sedimentary rocks. They used relative dating to divide Earth's past in several chunks of time when similar organisms were on Earth.
Scientists divide Earth's entire 4.6 billion years into four major time periods. The oldest — and by far the longest — is called the Precambrian. It is divided into Eons known as the Hadean (HAY-dee-un), Archean (Ar-KEY-un), and Proterozoic (Pro-tur-oh-ZOE-ik). After the Precambrian come to the Paleozoic Era and Mesozoic Era.
In interpreting rock age the use of relative dating puts the sequences of rocks layers into chronological order. Although the layers are no longer horizontal, geologists are able to determine their order.
Examples interpreted from rock strata provide a way to organize Earth's history. Analyses of rock strata and the fossil record provide only relative dates, not an absolute scale. phenomena can be observed at various scales using models to study systems that are too large or too small.
