The term 'long geological time' can be summarized as an EON, which is a unit of geological time that is equal to one billion years. An EON is the longest division of geological time and is divided into eras, which are further divided into periods, epochs, and ages. Eons are used to describe the history of the Earth and its life forms, and they are typically divided into two main categories: the Phanerozoic EON (the current EON) and the Precambrian EON (the earlier EON).