Context: Geologists have said that sediments at Crawford Lake in Canada’s Ontario have provided evidence of the beginning of the Anthropocene epoch.

About Anthropocene epoch:

• It is a proposed geological epoch.
• Term coined by: Nobel Prize-winning chemist Paul Crutzen and biology professor Eugene Stoermer.
• What does it denote?:It denotes the present geological time interval, in which the Earth’s ecosystem has gone through radical changes due to human impact, especially since the onset of the Industrial Revolution.
• Unwelcome changes: It is associated with global warming, sea-level rise, ocean acidification, mass-scale soil erosion, the advent of deadly heat waves, deterioration of the biosphere and other detrimental changes in the environment.
• Estimated beginning of epoch: Members of the Anthropocene Working Group (AWG) have estimated that the new epoch started sometime between 1950 and 1954.
• Lack of consensus: There are disagreements within the scientific community regarding when it began, or has it already begun, or if they have enough evidence to prove its advent.

Crawford Lake in Canada and recent study 

• Site of examination: Crawford Lake was chosen for examination as its layers of sediment preserved the annual impact of human activities on the Earth’s soil, atmosphere and biology.
• Evidence: 
  • Advent: There are distinct and multiple signals starting around 1950 in the water body, which showed that the effects of humans overwhelm the Earth system.
  • Destructive humanising of Earth: The presence of plutonium (due to detonation of nuclear weapons) indicates when humanity became such a dominant force that it could leave a unique global ‘fingerprint’ on Earth.
• Inconclusive evidence: These findings don’t mean that they have proved the advent of the Anthropocene epoch

Earth’s geological time scale

• The geologic time scale is the “calendar” for events in Earth history. 
• Subdivision: It subdivides all time into named units of abstract time called—in descending order of duration— eons, eras, periods, epochs, and ages. 
• Methodology: The enumeration of those geologic time units is based on stratigraphy, which is the correlation and classification of rock strata. 
• Fossil markers:The fossil forms that occur in the rocks, however, provide the chief means of establishing a geologic time scale, with the timing of the emergence and disappearance of widespread species from the fossil record.

News Source: Indian Express