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Because of the somewhat short half-life of 14C, radiocarbon dating is not applicable to samples with ages greater than about 50,000 years, because the remaining concentration would be too small for accurate measurement.
Thermoluminescence dating: this method is associated with the effect of the high energy radiation emitted as a result of the decay or radioactive impurities.
The fossil record is fundamental to an understanding of evolution.
Fossils document the order of appearance of groups and they tell us about some of the amazing plants and animals that died out long ago.
In the past 150 years they have not found any fossils that Darwin would not have expected.
New discoveries have filled in the gaps, and shown us in unimaginable detail the shape of the great ‘tree of life’.
Age estimates can be cross-tested by using different isotope pairs.
Results from different techniques, often measured in rival labs, continually confirm each other.
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.Today, innovative techniques provide further confirmation and understanding of the history of life.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.Fossils can also show us how major crises, such as mass extinctions, happened, and how life recovered after them.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.
Some critics, particularly religious fundamentalists, argue that neither fossils nor dating can be trusted, and that their interpretations are better.