So far, fifty-two values of the terrestrial heat flow in Czechoslovakia are known^{1â 4}. The points at which the heat flow has been determined are marked on the map together with schematic boundaries of the main tectonic formations (Fig. 1). Tectonically, Czechoslovakia contains parts of two distinctly different provinces of European geological structure; the western part of Czechoslovakia (the Bohemian Massif) belongs to the Variscan province, and the eastern part, formed by the West Carpathians, belongs to the Alpine province. Both of these formations are divided by the comparatively narrow Carpathian Foredeep. Whereas the Bohemian Massif is a formation which has long since been consolidated, the western Carpathians are part of a young zonal mountain range where geosynclinal development is still in progress.