The finite element technique is used to solve the continuity equation for two modeling experiments which investigate the response of Ice Stream C to changes in the boundary conditions. By comparison of the results of these experiments it is possible to delineate the mechanism resonsible for the anomalously low observed velocity. These experiments are (1) the sudden capture of a major portion of Ice Stream C's catchment area by neighboring Ice Stream B and (2) the sudden removal of a sliding bed condition along a major portion of Ice Stream C. The results of these experiments favor the second scenario over the first as being responsible for the present state of Ice Stream C and suggest that the sliding condition on Ice Stream C disappeared approximately 2000 years ago. ¿ American Geophysical Union 1987