Here's why:
* Geological Time Scale: Geologists use the geological time scale, which divides Earth's history into eons, eras, periods, and epochs. Each division has a specific age range, but within those ranges, the color used is often determined by the type of rock present, not solely the age.
* Rock Types: Different types of rock are represented with different colors. Sedimentary rocks might be brown, gray, or red, while igneous rocks might be black, white, or red.
* Maps and Diagrams: The specific color used can vary depending on the type of map or diagram. For example, a geological map might use different colors to represent different rock formations, while a tectonic plate map might use different colors to show the ages of different plate boundaries.
Instead of a single color, geologists use other methods to represent age:
* Color Gradients: Some maps use a color gradient, with older rocks represented by darker colors and younger rocks by lighter colors.
* Numbering: A numerical age may be given on the map or diagram, indicating the precise age in millions of years.
* Legend: Maps always include a legend that explains the meaning of the colors and symbols used.
So, while there's no single "100 million year old crust color," geologists use various methods to visually represent the ages of rocks and geological features.
