Geological Time
Definition and Importance of Geological Time
- Geological time represents the time scale of Earth’s history, which spans approximately 4.6 billion years.
- Understanding of geological time is crucial for geologists as it allows them to sequence events and understand the relative and absolute ages of rocks and the fossils contained within them.
- It is represented by geological time scale, a system of chronological measurement that relates stratigraphy to time.
The Geological Time Scale
- The most recent version of the geological time scale divides Earth’s history into eons, eras, periods, epochs and ages.
- The largest division, the eon, is divided into three: the Archean, the Proterozoic and the Phanerozoic, with the Phanerozoic subdivided further into three eras: the Paleozoic, Mesozoic, and Cenozoic.
- Each era is divided into periods, then epochs, and finally ages, with the more recent divisions having a greater level of detail and precision.
Dating Techniques used in Geology
- The age of rocks, minerals, and fossils can be determined using both relative and absolute dating techniques.
- Relative dating involves determining the comparative ages of objects, usually by examining their positions in the layers of rock or strata. Key concepts include the Law of Superposition, Principle of Original Horizontality, and Principle of Faunal Succession.
- Absolute dating, also known as numerical dating, provides a specific age or date range in calendar years. Techniques include radiometric dating (like carbon dating), dendrochronology, and thermoluminescence.
Application and Significance of Geological Time
- The understanding of geological time allows geologists and palaeontologists to interpret Earth’s history, including major geological events, evolution of life, and past climates.
- It provides a framework for the correlation of geological events globally.
- Geological time is vital in the petroleum industry, where understanding the timing of geological events can help in the exploration of oil and natural gas reserves.
The ‘Deep Time’ Concept
- ‘Deep time’ is a term that refers to the immensity of Earth’s history and geological time.
- The concept of deep time highlights that Earth’s history extends far beyond human experience and comprehension.
- It is through the study of geological time that we understand how insignificant human history is, relatively, compared to the age of the Earth.
- This concept promotes an awareness of the enormous time spans involved in geological processes, and the time required for the evolution and diversity of life.