Think about how the geologic time scale was created and how it is divided. Then answer the following questions.

How did scientists form the geologic time scale?

How is this scale organized?

What processes changed Earth's surfaces during Precambrian time?

Answers

1. Scientists form the geological time scale by describing the order and time when major earth events occurred for the last 4.5 billion years ago. The scale describes the first time plants appeared on earth, the first time animals where spotted on Earth, the processes that formed mountains and the extinction of special species such as the dinosaurs. Geologist study the earth to identify the history of geological events contained in the rock layers of the Earth. Old layers of the Earth are buried deep inside the surface where as the young layers are at the top. With this understanding, geologists are able to comprehend the ages of rocks relative to one another.

2. The Geologic time scale is organized into intervals namely Eons, Eras, Periods, and Ages. The Eons is the largest interval where each eon presents many millions of years. The Eons are divided into Eras which start and end with significant changes in the living organisms on the Earth surface. In each Era, there are multiple periods which are further subdivided into multiple short epochs.

3. The processes that changed Earth's surface during Precambrian time was changes in climatic condition that caused by creation of the planet and later the emergence of complex and multi-cellular organisms. The Precambrian time was characterized by layers of sedimentary rocks that formed million years ago and contain information of Earth's past which include fossils remains of living organisms that were buried during formation of sediments.