However, relative methods are , which is that if there are layers of deposits, those laid down first will be on the bottom and those laid down last will be on the top. However, geological strata are not always found to be in a neat chronological order.
Wind and water erode strata and some areas are uplifted or even tilted.
Fluorine will burn all sorts of compounds and elements including water, copper, gold, and steel. Because it is so reactive, fluorine does not occur as a free element in nature.
These processes result in All of these processes confuse the stratigraphic record.
In many cases, however, it is possible to reconstruct the original sequence of strata so that they can be used for relative dating.
For instance, if we find a fossil bone below the strata 3 rock level shown above, we assume that the animal most likely lived at a time before that layer was formed.
However, we must be careful to note whether or not the fossil comes from the mixed strata zone of the filled in hole..