klippes, which are the most characteristic features of the belt, are jurassic to lower cretaceous lenses - rigid blocks of limestone, tectonically separated from their unknown substratum. these blocks are also cropping out in tectonic windows in the overlying middle cretaceous to paleogene sediments. strong tectonic deformation is a result of two main phases during the alpine orogeny. the oldest phase is called the laramide phase or jarmuta phase and occurred in the cretaceous and paleogene periods. it caused thrusting of the nappes. the second phase is called the savian or helvetian phase. it was induced by subduction of the northern penninic ocean and caused the formation of the carpathian flysch belt.