A production system model has been developed for terrain analysis problem solving. The working memory of the production system is used to store specific domain knowledge about landforms. This involved the description of landforms in terms of their pattern elements, including their likelihood of occurrence. The production memory was used to store the rules of inferencing. These rules were general rules and were applicable to all landforms. Thus, the domain knowledge about terrain analysis was separated into two components: one component consisting of specific knowledge about landforms, stored as facts in the working memory; and the other component consisting of the general methodology for inferencing, stored as rules in the production memory. Such a separation of knowledge enables additions to the knowledge base fairly easily. The knowledge base can be extended to encompass more landforms simply by creating more working‐memory elements. The present version of the prototype expert system has been implemented using OPSS, a production system language. Uncertainty calculations were performed by invoking LISP functions from OPS5. The results indicated that the production system model was appropriate for designing the prototype expert system for terrain analysi