Approximately 1,500 geoid cross sections across 15 small-offset South Atlantic fracture zones (FZ's) are compiled from Seasat altimeter data and organized according to crustal age; these profiles provide a basis for the comparison of the different FZ's, and the evolution of each over geological time. I use an empirical orthogonal function decomposition to investigate the dependence of profile shape and amplitude upon crustal age. The geoid cross sections are found to be coherent in form down the length of each FZ, and possess amplitudes that are inversely related to the relative spreading rate at the time of formation. This observation is consistent with a simple model in which the active portion of a fractue zone (the transform fault) remains a fixed spatial length, yielding a variable age offset across the FZ. ¿ American Geophysical Union 1988