The age of the Earth is about 4.54 billion years old. The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago, during the Eoarchean Era after a geological crust started to solidify following the earlier molten Hadean Eon. There are microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia. Other early physical evidence of a biogenic substance is graphite in 3.7 billion-year-old metasedimentary rocks discovered in Western Greenland. More recently, in 2015, "remains of biotic life" were found in 4.1 billion-year-old rocks in Western Australia. According to one of the researchers, "If life arose relatively quickly on Earth ... then it could be common in the universe." COUNT 5
QSN1 What is the estimate age of the Earth? ANS1 about 4.54 billion years old QSN2 What era contains the earliest undisputed evidence of life on Earth? ANS2 the Eoarchean Era QSN3 What is the name of the era that predated life on Earth? ANS3 Hadean Eon QSN4 Where were the billion year old microbial mat fossils found? ANS4 Western Australia QSN5 Where were the 3.7 billion-year-old metasedimentary rocks discovered? ANS5 Western Greenland