The formative stages of the geosystem mapping methodology are outlined. It is determined that the early stages of geosystem mapping showed a continuity of the ideas of geobotanical mapping: concerning the hierarchical structure of the phytosphere, and the invariant and the variable states of plant communities. It was found that geosystem mapping involves integrating the facies according to structural and structural-dynamic indicators differing from a traditional typization. Data were generalized having regard to the assignment of the facies to a particular landscape area. Use was made of the facies categories of optimal, limited and reduced development caused by a difference in their structure and biotic productivity. It was determined that a next mapping stage implied identifying the dynamic categories and geosystem state variables associated with one primary geomer regarded as the parent core. The map legend was based on the characteristics of the relief and vegetation. The absence of other indicators has limited the possibilities of using the map to solve forecasting problems. It was established that at present, given a significant body of landscape data, there is almost no research devoted to the cartographic solution of the problem of assessing changes in the natural environment. There is a need for mapping of the structural, dynamic and genetic uniqueness of geosystems and to explain their diagnostic features in all crucial components. We determined that the current stage of mapping should be focused on solving the problem of geographical map-based forecasting. For solving the forecast issues, we identified the features of structural-dynamic and evolutionary transformations of geosystems, their stability, and the direction of transformation under the influence of various factors. The methodology of geosystem mapping are suggested.Keywords: geosystems, methodology, stages of mapping, structural and dynamic transformations, forecast.