1. A method for obtaining a topological map of textures of a geological medium, comprising she steps of: producing images characterizing the sedimentology of said medium; estimating parameters corresponding to said images at every point and in a spatial domain about said point of each image, in order to determine a texture vector for each of said points and obtain a set of texture vectors comprised of all determined texture vectors; selecting texture vectors from said set which are representative of characteristic textures of said geological medium; using a neural network which is formed of cells distributed in two dimensions and which comprises as many cells as characteristic textures, and applying a learning process to said neural network via said selected texture vectors in order to obtain a final topological map of said characteristic textures of the geological medium.