In an effort to determine the internal spatial characteristics of solute transport in naturally heterogeneous soils, recent applications of electrical resistance tomography to soil core tracing are reported. Using a high-speed, biomedical type data acquisition system, migration of an electrolytic tracer in an undisturbed soil column was monitored. Quantitative images produced from the collected data display an interesting sequence of patterns of internal tracer breakthrough at cross sections of the soil column. Analysis of pixel breakthrough behavior reveals spatial variation of transport characteristics throughout the soil column. ¿ American Geophysical Union 1996