Determining when humans started impacting the planet on a large scale

Humans have so profoundly altered the Earth that, some scientists argue, our current geologic epoch requires a new name: the Anthropocene. But defining the precise start of the era is tricky. Would it begin with the spread of domesticated farm animals or the appearance of radioactive elements from nuclear bomb tests? Scientists report a method to measure levels of human-made contaminants in sediments that could help pinpoint the Anthropocene’s onset.
Geology News — ScienceDaily