Answer: Volcanic eruptions
Geological events are the geological or we can say physical features which build up the history of the Earth. They are followed by a major event in Earth's past based on the geologic time scale. It is a system of chronological measurement based on the observation of the layers of the rocks on the planet Earth.
Some examples of geological events are volcanic eruptions, earthquakes, etc.
Volcanic eruptions are preserved as layers of rocks which can be studied as we go deep inside the Earth.