4. Time in geology

The Earth has been in a perpetual state of evolution for just over 4.5 billion years, and will continue to be so for almost as long! The Earth's present-day crust, and more specifically its continental part, has undergone a long and complex history following processes spread over a long "geological" time span. In their entirety, major geological processes such as the opening or closing of an ocean, the filling of a sedimentary basin or the formation of an orogen occur over periods of tens or hundreds of millions of years.

Understanding the history of the earth or of a given area requires an understanding of the relative chronology of past events, as well as the ability to precisely date certain events or rocks. Finally, observation and detailed measurements of the current evolution of the earth's surface on a human scale also enable us to better understand and quantify...