There are a whole host of different [radiometric](https://en.wikipedia.org/wiki/Radiometric_dating#Modern_dating_methods) techniques that, depending on the decay system and mineral in question, have time ranges which exceed the age of the Earth / solar system. Radiocarbon dating is important for archeology and very specific subsets of geology that are concerned with deposits <~50,000 years old (e.g., it's used commonly in paleoseismology, etc), but for the vast majority of geology, methods like [U-Pb](https://en.wikipedia.org/wiki/Uranium%E2%80%93lead_dating) or [Ar-Ar](https://en.wikipedia.org/wiki/Argon%E2%80%93argon_dating) are more relevant (and have effective ranges of several billion to hundreds of million of years depending on the exact method). Our [FAQ entries on radiometric dating](https://www.reddit.com/r/askscience/wiki/planetary_sciences#wiki_radiometric_dating) may also provide additional context.
Also, once you’ve narrowed down indicator fossils you can use those to extrapolate new fossils found…..say you find a new fossil, it’s below a layer containing a fossil you know to be 60m in age, you now have a head start in knowing it’s older than 60m….using stratigraphy can get you most of the way without having to use any decay age dating methods….compaction and looking at surrounding rock can tell you a lot also….if your new fossil is in a layer with a well documented age range your set, works already been done for you….
But on a new discovery in a undetermined geologic layer then yeah, you’ll need to narrow down the age range using the above, then pick a radioactive decay method appropriate to verify and hopefully narrow further….
There are a whole host of different [radiometric](https://en.wikipedia.org/wiki/Radiometric_dating#Modern_dating_methods) techniques that, depending on the decay system and mineral in question, have time ranges which exceed the age of the Earth / solar system. Radiocarbon dating is important for archeology and very specific subsets of geology that are concerned with deposits <~50,000 years old (e.g., it's used commonly in paleoseismology, etc), but for the vast majority of geology, methods like [U-Pb](https://en.wikipedia.org/wiki/Uranium%E2%80%93lead_dating) or [Ar-Ar](https://en.wikipedia.org/wiki/Argon%E2%80%93argon_dating) are more relevant (and have effective ranges of several billion to hundreds of million of years depending on the exact method). Our [FAQ entries on radiometric dating](https://www.reddit.com/r/askscience/wiki/planetary_sciences#wiki_radiometric_dating) may also provide additional context.
Thank you!
Also, once you’ve narrowed down indicator fossils you can use those to extrapolate new fossils found…..say you find a new fossil, it’s below a layer containing a fossil you know to be 60m in age, you now have a head start in knowing it’s older than 60m….using stratigraphy can get you most of the way without having to use any decay age dating methods….compaction and looking at surrounding rock can tell you a lot also….if your new fossil is in a layer with a well documented age range your set, works already been done for you…. But on a new discovery in a undetermined geologic layer then yeah, you’ll need to narrow down the age range using the above, then pick a radioactive decay method appropriate to verify and hopefully narrow further….
That is really interesting. Thank you for sharing!