The Geologic Calendar is a scale in which the lifetime of the earth is mapped onto a calendrical year; that is to say, the day one of the earth took place on a geologic January 1 at precisely midnight, and today's date and time is December 31 at midnight. On this calendar, the life on Earth arose on November 15, the first dinosaurs appeared on December 27th, the first flowers on December 30th and the first primates on December 31. The first humans did not arrive until around 11:56 p.m. on New Year's Eve, and all of human history has been recorded in the last 4 seconds.
A Geologic Calendar is a time scale that covers the Earth's entire geologic history from its origin to the present. Before the growth of a geologic time scale in the 19th century, natural historians recognized that the Earth had a lengthy history. The scale used today was developed over the last 200 years and continues to evolve.
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