Radioactive carbon dating of fossils sungod 89 dating sites
At the oldest, or deepest layer of rock there was no record of fossils, but then they noticed that simple sea creatures were found at the next higher level, then more complex ones like fishes at the next higher level and so on.
Next came life on land, then reptiles, then mammals, and finally humans.
It took a canal surveyor circa 1800, William Smith in England, who noticed that he could map out great tracts of rocks on the basis of their contained fossils.
Besides the order of fossils in the rocks, another method is the use phylogenetic trees.
Phylogenetic trees are used to show how all the species of particular groups of plants or animals relate to each other.
One records which fossil is younger and which is older.
The discovery of a different means, one for which absolute dating is possible occurred in the early 20th century. Certain naturally occurring elements are radioactive, and they break down or decay at well-known predictable rates.
Carbon Dating Carbon-14 dating is the best-known absolute dating technique.