A series of geological sections across the Colombian Andes along the 4° latitude N, illustrates the evolution of the paleogeography from Cambrian to Upper Tertiary. The main stratigraphical units are described, as well as the associated magmatic rocks. Each Colombian Cordillera was built in a definite paleogeographical area. The Eastern Cordillera belongs to the Caledonian orogenic belt, the Central Cordillera to the Hercynian orogenic belt, the Western and Coastal Cordillera to the Laramian one. Thus one observes a progressive lateral shifting of the orogenic belts from E to W. It is assumed here that the Precambrian was not involved into younger tectonical movements. To the W of each orogenic belt, geosynclinal sediments were deposited directly on the moving oceanic crust. At the end of this period of tension within the continental crust, mountain building started, mainly produced by a constant accretion of the continent to the W.