What does the Geologic Time Scale combine?

The Geologic Time Scale is a system that organizes Earth's history into various intervals based on significant geological and biological events. It combines relative ages, which place rocks and events in order of occurrence without providing specific numerical dates, with isotopic ages, which give precise numerical dates for rocks and events based on radiometric dating techniques.

By integrating both relative and isotopic ages, the Geologic Time Scale allows scientists to develop a comprehensive understanding of Earth's history. Relative dating helps in determining the chronological order of geological formations and events, while isotopic dating provides the actual age of these formations, enabling a more accurate timeline of geological processes.

The other options either restrict the scope of evidence used (such as only focusing on sedimentary records or fossil evidence) or exclude crucial components of the Geologic Time Scale, making the first option the most accurate representation of how the scale has been developed and used within geology.