Yet, you’ve heard the news: Earth is 4.6 billion years old. That corn cob found in an ancient Native American fire pit is 1,000 years old. Geologic age dating—assigning an age to materials—is an entire discipline of its own.
In a way this field, called geochronology, is some of the purest detective work earth scientists do.
Early geologists, in the 1700s and 1800s, noticed how fossils seemed to occur in sequences: certain assemblages of fossils were always found below other assemblages. Since 1859, paleontologists, or fossil experts, have searched the world for fossils.
In the past 150 years they have not found any fossils that Darwin would not have expected.
Paleontologists now apply sophisticated mathematical techniques to assess the relative quality of particular fossil successions, as well as the entire fossil record.Biologists actually have at their disposal several independent ways of looking at the history of life - not only from the order of fossils in the rocks, but also through phylogenetic trees. Relative dating is done by observing fossils, as described above, and recording which fossil is younger, which is older.The discovery of means for absolute dating in the early 1900s was a huge advance.If the fossils, or the dating of the fossils, could be shown to be inaccurate, all such information would have to be rejected as unsafe.Geologists and paleontologists are highly self-critical, and they have worried for decades about these issues. D., is a vertebrate paleontologist with particular interests in dinosaur origins and fossil history.These demonstrate that, of course, we do not know everything (and clearly never will), but we know enough.