Which unit of geologic time encapsulates two or more periods?

Which unit of geologic time encapsulates two or more periods?

• A. Epoch
• B. Era
• C. Age
• D. Interval

Answer: (B)

The concept of geologic time is organized into a hierarchical framework that includes eons, eras, periods, epochs, and ages, with each unit representing different lengths of time and levels of geological and biological significance. An era is a substantial division within the geological time scale that encompasses two or more periods. For example, the Mesozoic Era includes the Triassic, Jurassic, and Cretaceous periods. This makes eras significant not only in terms of the time they represent but also in the major events that characterize them, such as the rise and fall of dominant species or substantial geological changes. In contrast, epochs and ages represent subdivisions of periods and are thus smaller units of time. An interval is a less formal term that does not correspond to a defined unit in the geological time scale. Therefore, era is the best fit as it denotes a broader timespan that encompasses multiple periods.

The concept of geologic time is organized into a hierarchical framework that includes eons, eras, periods, epochs, and ages, with each unit representing different lengths of time and levels of geological and biological significance.

An era is a substantial division within the geological time scale that encompasses two or more periods. For example, the Mesozoic Era includes the Triassic, Jurassic, and Cretaceous periods. This makes eras significant not only in terms of the time they represent but also in the major events that characterize them, such as the rise and fall of dominant species or substantial geological changes.

In contrast, epochs and ages represent subdivisions of periods and are thus smaller units of time. An interval is a less formal term that does not correspond to a defined unit in the geological time scale. Therefore, era is the best fit as it denotes a broader timespan that encompasses multiple periods.