Dating earth sub espanol
Older dates may change by a few million years up and down, but younger dates are stable.
For example, it has been known since the 1960s that the famous Cretaceous-Tertiary boundary, the line marking the end of the dinosaurs, was 65 million years old.
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.
Darwin and his contemporaries could never have imagined the improvements in resolution of stratigraphy that have come since 1859, nor guessed what fossils were to be found in the southern continents, nor predicted the huge increase in the number of amateur and professional paleontologists worldwide.Results from different techniques, often measured in rival labs, continually confirm each other.Every few years, new geologic time scales are published, providing the latest dates for major time lines.All these labors have not led to a single unexpected finding such as a human fossil from the time of the dinosaurs, or a Jurassic dinosaur in the same rocks as Silurian trilobites.Paleontologists now apply sophisticated mathematical techniques to assess the relative quality of particular fossil successions, as well as the entire fossil record.