Absolute vs relative dating fossils

The most obvious feature of sedimentary rock is its layering.

This feature is produced by changes in deposition over time.

Experts can compare the ratio of carbon 12 to carbon 14 in dead material to the ratio when the organism was alive to estimate the date of its death.Such a preserved specimen is called a "fossil" if it is older than some minimum age, most often the arbitrary date of 10,000 years.The observation that certain fossils were associated with certain rock strata led early geologists to recognize a geological timescale in the 19th century.William Smith was one of the most important scientists from this time who helped to develop knowledge of the succession of different fossils by studying their distribution through the sequence of sedimentary rocks in southern England.It wasn't until well into the 20th century that enough information had accumulated about the rate of radioactive decay that the age of rocks and fossils in number of years could be determined through radiometric age dating.

Absolute vs relative dating fossils