We propose a new multi-scale terrain model, based on a hierarchical representation for the morphology of a terrain. The basis of our morphological model is a dual Morse decomposition of the terrain, composed by the stable and unstable manifolds defined by its critical points and its integral lines. We propose a two-level representation of the dual Morse decomposition and we define new simplification operators for the Morse decomposition which act on such representation. Based on these operators, we define a hierarchical morphology-based representation, that we call a Multi-scale Morse Complex (MMC). Results from our implementation of the MMC are presented. Categories and Subject Descriptors E.1 [Data Structures] General Terms Algorithms. Keywords Terrain Modeling, Morphology, Multi-Scale Representations.