Volcanic rocks – such as tuff and basalt – can be used in dating because they are formed at a particular moment in time, during an eruption.
Sedimentary rocks are rarely useful for dating because they are made up of bits of older rocks.
It is important to remember that this method give the age of the mineral, not the artifact.
So we can't pick up an artifact that's made from volcanic rock and get a potassium argon date on the artifact.
Archaeologists work on the principle that objects at the bottom of an undisturbed were put there before objects that are above them, so objects found in the lower levels of a site are usually older than objects found in higher levels.
Uranium is present in many different rocks and minerals, usually in the form of uranium-238.
For more than three decades potassium-argon (K-Ar) and argon-argon (Ar-Ar) dating of rocks has been crucial in underpinning the billions of years for Earth history claimed by evolutionists. Lassen plagioclase, California (AD 1915) 0.11±0.03 Ma Sunset Crater basalt, Arizona (AD 1064-1065) 0.27±0.09 Ma; 0.25±0.15 Ma Akka Water Fall flow, Hawaii (Pleistocene) 32.3±7.2 Ma Kilauea Iki basalt, Hawaii (AD 1959) 8.5±6.8 Ma Mt.
This method can give archaeologists an indication of the age of the artifacts in all Absolute dating methods can give an estimate of the real calendar age of an artifact or site.
There are several absolute dating methods that archaeologists can use, including radiocarbon dating and potassium argon dating.potassium) decays into argon over time, so the age of certain rocks or minerals can be discovered by measuring the amount of argon they contain.