These techniques can be grouped as numerical, relative dating, and correlation.
Numerical techniques are best, but datable materials are often lacking, and in these cases age estimation must be made using relative-dating or correlation techniques.
In order to move towards such integration, a series of methodological challenges have to be met.
In parallel with the possibility of detecting hitherto invisible tephras over vastly increased areas, the overall potential of tephrochronology as a major dating tool for both palaeoenvironmental scientists and archaeologists is greatly expanded.
New dating methods are invented all the time, however, most have practical limitations.
Geologic research and mapping requires the determinations of the ages and composition of rocks.
Geologic studies of active tectonism are greatly aided by definition and time calibration of local stratigraphic sequences.
Because all dating techniques may be subject to considerable error, reliability should be assessed by stratigraphic consistency between results of different dating methods or of the same method.