Sequential data can be segmented by the techniques of (1) numeric differentiation, (2) split moving window, (3) maximum level variance, and (4) piecewise regression. Each method is compared and contrasted with the others for performance with different types of data strings. In geology, data strings could be electric logs (or other borehole logs), seismic traces, x-ray curves, or traverses measuring some property with distance. Segmenting traces into like parts with uniform characters facilitates comparison and correlation.