Geologic dating techniques
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.
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.
Current understanding of the history of life is probably close to the truth because it is based on repeated and careful testing and consideration of data.
The rejection of the validity of fossils and of dating by religious fundamentalists creates a problem for them: Fossil sequences were recognized and established in their broad outlines long before Charles Darwin had even thought of evolution.
The fossil record is fundamental to an understanding of evolution.The methods are all based on radioactive decay: The first radiometric dates, generated about 1920, showed that the Earth was hundreds of millions, or billions, of years old.Since then, geologists have made many tens of thousands of radiometric age determinations, and they have refined the earlier estimates.A key point is that it is no longer necessary simply to accept one chemical determination of a rock’s age.Age estimates can be cross-tested by using different isotope pairs.
These demonstrate that, of course, we do not know everything (and clearly never will), but we know enough.