Two ways of dating fossils
After death the amount of carbon-14 in the organic specimen decreases very regularly as the molecules decay. Students not only want to know how old a fossil is, but they want to know how that age was determined.
It is estimated to require four hours of class time, including approximately one hour total of occasional instruction and explanation from the teacher and two hours of group (team) and individual activities by the students, plus one hour of discussion among students within the working groups.over the last half century nuclear science, radiography, chemistry and physics have developed laboratory procedures for determining accurately the absolute date of any stratigraphy.some of these methodologies are referenced in the other answers.there are several entries in wikipedia which provide good overviews of the question and numerous web sites that explain how to go about archaeological, paleontological and geological as dr.Radiocarbon dating involves determining the age of an ancient fossil or specimen by measuring its carbon-14 content.Carbon-14, or radiocarbon, is a naturally occurring radioactive isotope that forms when cosmic rays in the upper atmosphere strike nitrogen molecules, which then oxidize to become carbon dioxide.Age determination of rocks falls into two categories - absolute dating and relative dating. Just as we can determine the age of organic objects by carbon dating them, we can determine the age of some rocks using the half-lives of isotopes of substance like potassium, thorium, and uranium.
Relative dating is done by various means using empirical geologic data.
The methods work because radioactive elements are unstable, and they are always trying to move to a more stable state. This process by which an unstable atomic nucleus loses energy by releasing radiation is called radioactive decay.
The thing that makes this decay process so valuable for determining the age of an object is that each radioactive isotope decays at its own fixed rate, which is expressed in terms of its half-life.
every stratum has its unique profile, whereby the relative chronology is verified.
paleomagnetism and isotope ratios along with biostratigraphy identify the strata of the local geology and determine their relative chronology.
By examining the object's relation to layers of deposits in the area, and by comparing the object to others found at the site, archaeologists can estimate when the object arrived at the site.