An interactive computer simulation which erects models of sedimentary geometries by filling in a two-dimensional basin from both sides with a combination of clastic sediment and/or in situ and transported carbonate sediments is described. The simulation program is implemented in ''C'' using graphical plotting functions. Data entry, including the initial basin configuration, the local tectonic behavior, the sea level curves, the amount and source direction of clastic sediment, and the growth rates of carbonates as a function of water depth is performed interactively. Geometries of clastic and carbonate sediments evolve through time and respond to tectonic movement, eustasy, and sedimentation. Clastic modeling includes sedimentary bypass and erosion and sedimentation in alluvial and coastal plains, marine shelf, basin slope, and basin floor settings. Carbonate modeling includes progradation, the development of hard grounds, downslope aprons, keep up, catch up, back step, and drowned reef settings as well as lagoonal and epeiric settings. Also included in the model are extensional vertical faulting of the basin, sediment compaction, and isostatic response to sediment loading. Sediment geometries are plotted on a graphics terminal as they are computed, so the user can immediately view the results. Based on these observations, parameters can be changed and the program rerun until the user is satisfied with the resultant geometry. This paper includes output showing the simulation' sensitivity to eustatic sea level variations, and variations in sedimentation and subsidence rates. Also shown are outputs demonstrating the modeling of some examples from the geologic section in the Permian Basin of west Texas and the Upper Permian of the Sichuan Basin. ¿American Geophysical Union 1991