The span of conceivable past time increased explosively when artificial mental restraints were removed less than 200 years ago. Unfortunately, doctrines and practices of stratigraphy were already established before emancipation. Perhaps for this reason, time has tended to take an inferior place in philosophical discussions of the time-rock relationship, and weaknesses and fallacies have been less easily perceived. Though the formation of any sequence of strata obviously occupied some finite span of time, it does not follow in reverse that the total span of continuous past time can properly be classified or subdivided into arbitrary intervals defined by selected separate rock sequences. The validity of the type section and the usefulness of the time-stratigraphic unit are therefore held in doubt. On the other hand, the concepts of “biochron” and “zone” as used in one sense offer a sound basis for geological age-measurement and a means for referring geological age to radiometrically determined points on the continuous secular time scale. It is predicted that the traditional geological time divisions will be retained in use along with the secular time scale, but will eventually be redefined in terms of the latter.