Linear time scales are used by exploration paleontologists to establish a numeric chronostratigraphy for marine well sections which include calculated estimates for the missing intervals at unconformities. A new kind of cross section can be constructed using isochrons, showing chronostratigraphic depositional patterns similar to the seismic record. The geochronologic resolution of isochron cross sections is normally higher than that of seismic sections, so it can be used in the calibration and interpretation of the seismic record and in its extrapolation in "bad data" areas. The depth-distance sections portray sediment accumulation rate patterns and form a useful base to plot parameters such as source and reservoir facies and geochemical and geophysical data. The umeric stratigraphic technique is particularly useful to continental margin explorationists where marine microfauna aid its application. With known vertical movements of a passive margin, the method detects sea level changes (that determined the sedimentary pattern) and local anomalies such as salt or shale movements.