Three geologists have reported what they called the first "successful" direct dating of dinosaur bone. Will this new radioisotope dating or radiodating technique solve the problems that plagued older dating methods? If history is anything to go by, then the answer is no. The process generally used to date a fossil is circuitous and subject to differing interpretations.
Why can't most sedimentary rocks be dated radio metrically? | Yahoo Answers
Originally, fossils only provided us with relative ages because, although early paleontologists understood biological succession, they did not know the absolute ages of the different organisms. It was only in the early part of the 20th century, when isotopic dating methods were first applied, that it became possible to discover the absolute ages of the rocks containing fossils. In most cases, we cannot use isotopic techniques to directly date fossils or the sedimentary rocks in which they are found, but we can constrain their ages by dating igneous rocks that cut across sedimentary rocks, or volcanic ash layers that lie within sedimentary layers. Isotopic dating of rocks, or the minerals within them, is based upon the fact that we know the decay rates of certain unstable isotopes of elements, and that these decay rates have been constant throughout geological time. It is also based on the premise that when the atoms of an element decay within a mineral or a rock, they remain trapped in the mineral or rock, and do not escape. It has a half-life of 1. In order to use the K-Ar dating technique, we need to have an igneous or metamorphic rock that includes a potassium-bearing mineral.
why is it almost impossible to date sedimentary rocks using radiometric dating techniques?
Sedimentary rocks cannot be dated directly using radiometric dating, which is based on the idea that when rocks are in liquid form, their radiometric clock resets. Clastic sedimentary rock on the other hand consists of various clasts which were removed and deposited somewhere else by some sort of fluid generally wind and water. The sedimentary clasts predate the rock which they form. In addition, the redeposition process upsets the conditions necessary to achieve accurate results through radiometric dating.
Carbon, found in the ratio of isotopic ratios in southern africa, amino acids, tree rings. Development of the percentage of the age of years old. Most useful for over half lives and basis of years old. There are searching, you understand the radioactive atom. New ways of their radioactive decay provide a meteorite.