The Karstlands of Western Yugoslavia. 397 



It is the above-mentioized Triassic and Cretaceous dolomites 

 and limestones, remarkable for their extreme purity, that con- 

 stitute by far the greater portion of the terrain on which the karst 

 features are so admirably developed. 



The base of the Tertiary formation in this region is indicated by 

 freshwater limestones and marls, characterized by the shell Cosinia. 

 Above these succeeds a series of Nummulitic and Foraminiferal 

 limestones and marls ; replaced, however, in Central Dalmatia by 

 an extensive development of " Flysch ", a thick arenaceous 

 formation. The Promina Shale Series, which constitute the upper- 

 most Eocene in Dalmatia, forms also essentially a sandy facies 

 with thin alternations of marine limestones and marls. Marine 

 limestones of Neogene age are only met with in Southern 

 Montenegro ; throughout the Illyrian karstlands the lacustrine 

 Levantine deposits rest discordantly on the older Secondary and 

 Lower Tertiary formations. 



According to Penck, Schubert (11), and the former Austrian 

 Geological Survey, the folding of the beds in this region took place 

 in early Miocene times ; since which period also this district has 

 formed part of a land area. The rocks have been strongly folded 

 and faulted by a series of overthrusts from the north-east and east, 

 and the Eocene limestones which have participated in the move- 

 ments form long strips trending south-east overridden in many places 

 by Cretaceous limestones. Further inland, where the movement 

 appears to have been more intense, masses of Triassic limestone have 

 been thrust over Jurassic limestones, as in the notable case of the 

 Idria quicksilver mines (where the complicated structure has been 

 unravelled by Kossmatt),^ and also around Sarajevo, Vares, and 

 other localities in Central Bosnia. Many areas also formerly regarded 

 as having a simple, basin-like structure in Northern Dalmatia have 

 been shown by Schubert within recent years to have been strongly 

 folded and inverted in many places, while in the Siverich coalfield, 

 to the north of Sebenico, there is abundant evidence of powerful 

 earth-movements both in the presence of overthrusting and the 

 occurrence of shatter-belts (Verrussungszonen), along which the coals 

 show an impure and earthy character. 



The main axes of folding of the rocks in Western Yugoslavia 

 follow a N.W.-S.E. (Dinaric) trend, but to this broad generalization 

 there are several notable exceptions. Thus, in the neighbourhood 

 of Sebenico the Dinaric N.W.-S.E. direction changes eventually to 

 east and west. This strike is maintained in the islands of Brazza, 

 Lesina, and Curzola, and also on the adjoining mainland around 

 Spljet. Li Southern Montenegro the Dinaric N.W.-S.E. system 

 again curves inland, following the eastern and eventually E.N.E. 

 trend of the Prokletije mountains or Northern Albanian Alps. 



^ F. Kossmatt, " Ueber die geol. Verhaltnisse cles Bergbaugebietes von 

 Idria " : Jahrb. k. L geol. Rekhsanstalt, Vienna, vol. xlix, 1899, pp. 262-81. 



