Which of the following events separate geologic time into eras and periods?
Responses
the appearance and disappearance of groups of organisms
the appearance and disappearance of groups of organisms
the appearance and disappearance of volcanoes
the appearance and disappearance of volcanoes
the creation of new ocean ridges
the creation of new ocean ridges
the number of earthquakes occurring at that time
1 answer
The appearance and disappearance of groups of organisms
1 answer