Geologic Time Scale (GTS)

• It is designed by scientists to measure the history of the planet Earth.
• The GTS is divided, in descending order of duration, into aeons, eras, periods, epochs, and ages since the formation of Earth
• It is based on chronostratigraphic classification: It is an aspect of stratigraphy that deals with the relation between rock strata and the measurement of geological time.
  • Stratigraphy is a branch of geology that deals with the study of rock layers (or strata). 
• Characteristics of Chronostratigraphic units: 
  • They are not uniform and any two aeons, eras, periods, epochs, and ages do not encompass the same length of time.
  • Marked by events: Transition from one to another is marked by events that shape the planet and its living conditions.
  • Criteria: Each interval of Earth time must have a clear objective and a universally applicable starting point.

The International Union of Geological Sciences (IUGS)

• Established: It was founded in 1961 and is one of the largest scientific organizations engaged in geological sciences.
• Members: It has 121 national members, representing over a million geoscientists with membership open to countries or defined regions. 
• It encourages international co-operation and participation in the Earth sciences in relation to human welfare and is a member of the International Science Council (ISC).
• Function: IUGS promotes and encourages the study of geological problems, and supports and facilitates international and interdisciplinary cooperation in the Earth sciences.
  • With special consideration given to international standards; geoscience education; geoscience information; environmental management and hazards.

The International Commission on Stratigraphy (ICS)

• It is the largest and oldest constituent scientific body in the International Union of Geological Sciences (IUGS). 
• Objective: It  is to define precisely global units (systems, series and stages) of the International Chronostratigraphic Chart which is the basis for the units (periods, epochs and age) of the International Geological Time Scale
  • It sets the  global standards for the fundamental scale for expressing the history of the Earth.
• Subcommission: The work of the Commission is divided between seventeen subcommissions, each responsible for a specific period of geological time.

Holocene Epoch:

• Its name derives from the Greek “holos”, meaning ‘whole’, and “kainos”, meaning “new”
• It began some 11,700 years ago, at the end of the Last Glacial Period (LGP).
  • Ice Age: Upto 25% of the Earth’s land surface was covered by glaciers, the mean sea level was up to 400 feet lower, and the average temperature fell to 8 degree Celsius.
• The Holocene Period: It saw the warming of the Earth, and an end of Ice Age resulted in the rise of sea level and proliferation of human beings.
  • Basically all of humanity’s recorded history falls in this epoch.