In an interdisciplinary effort among geologists and statisticians, this project seeks to improve methods of time correlation in stratigraphy. By combining the best aspects of existing methods of graphical correlation with operations research, PIs will develop a solution in the form of constrained optimization. One part of the procedure seeks the best sequence of first and last appearance events, allowing subjective judgments about quality of data; a second part positions the events along a time scale by adding simplifying assumptions about accumulation rates. Repeated, rapid trials expose the consequences of different judgments and assumptions. Procedure will be applied to a mid- Ordovician correlation problem in the Great Basin.