Geologic Epoch
A Geologic Epoch is a time period that is smaller than a period and larger than an age.
- Context:
- It can (typically) be part of a larger Geologic Period, such as the Paleogene or Neogene.
- It can (often) be identified through distinct fossil records and geological strata.
- It can range from being a Pleistocene Epoch to being a Holocene Epoch.
- It can reflect major changes in Earth's climate, environment, and biodiversity.
- It can include multiple Geologic Ages, which are even smaller divisions of time.
- It can be determined and standardized by the International Commission on Stratigraphy.
- ...
- Example(s):
- the Pleistocene Epoch (~2.6 million to ~11,700 years ago), which saw the last Ice Age.
- the Holocene Epoch (~11,700 years ago to present), characterized by the development of human civilizations.
- the Miocene Epoch (~23 million to ~5.3 million years ago), known for the expansion of grasslands.
- ...
- Counter-Example(s):
- a Geologic Period, such as the Cretaceous Period, which is a larger division of geological time.
- a Geologic Age, such as the Late Pleistocene, which is a smaller division within an epoch.
- See: Geologic Period, Geologic Age, Chronostratigraphy, International Commission on Stratigraphy.
References
2024
- Perplexity
- A geological epoch is a subdivision of geological time that is smaller than a period and larger than an age. Epochs are used to describe specific intervals of time within a period, characterized by significant geological and paleontological events.
- Key Points about Geological Epochs
1. **Hierarchy and Division**:
- Geological time is divided into several hierarchical levels: eons, eras, periods, epochs, and ages. Epochs are subdivisions of periods and are further divided into ages[4][5]. - For example, the Cenozoic era is divided into three periods: the Paleogene, Neogene, and Quaternary. These periods are further divided into epochs such as the Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene[4].
2. **Naming and Standardization**:
- The naming and standardization of geological epochs are managed by the International Commission on Stratigraphy (ICS), which aims to define global units of the International Chronostratigraphic Chart. This ensures consistent use of terms across different regions and disciplines[4].
3. **Chronostratigraphic Units**:
- Chronostratigraphy deals with the relationships between time and the rocks deposited within those time intervals. The terms used in chronostratigraphy for epochs are 'series' and for ages are 'stages'[3].
4. **Principles of Relative Dating**:
- The determination of the relative ages of rocks and fossils within epochs relies on principles such as superposition, original horizontality, lateral continuity, faunal succession, cross-cutting relationships, and inclusion[1][5].
5. **Recent Developments**:
- There have been recent proposals to refine the geochronometric divisions of the pre-Cryogenian geologic time scale, including changes to the Archean and Proterozoic eons. These proposals aim to better align the divisions with the rock record and improve the accuracy of the geological time scale[1].
6. **Anthropocene Epoch**:
- The Anthropocene is a proposed epoch that highlights the significant impact of human activities on Earth's geology and ecosystems. It marks the end of the Holocene epoch and is characterized by transformations such as urbanization, mining, and environmental changes[2].
- Example of Epochs in the Cenozoic Era
| Period | Epochs | |-------------|---------------------------------------------| | Paleogene | Paleocene, Eocene, Oligocene | | Neogene | Miocene, Pliocene | | Quaternary | Pleistocene, Holocene, (proposed Anthropocene) |
Understanding geological epochs helps scientists and researchers to communicate about specific intervals of Earth's history and correlate geological and paleontological data across different regions.
Citations: [1] https://en.wikipedia.org/wiki/Geologic_time_scale [2] https://ecoartspace.org/New-Geologic-Epoch-2023 [3] https://www.bgs.ac.uk/discovering-geology/fossils-and-geological-time/geological-timechart/ [4] https://simple.wikipedia.org/wiki/Epoch_%28geology%29 [5] https://www.digitalatlasofancientlife.org/learn/geological-time/geological-time-scale/