Basic Principal of Geological Reconstruction Geological reconstruction is a process to describe geological phenomenon consisted of topography, geological structure and lithology. Basic principal in geological reconstruction that is having topographical data that can be obtained by topographical survey or DEM data that is available in many sources, geological structure and lithology. Geological structure identification is very important aspect in studying geology. Aspect related to geological structures is landform on surface. Landform classification uses the main principal about morphological formation referring to geological processes either endogenous or exogenous. Figure 1. Geological Reconstruction Principal