306 G. Stefanini — Outline of the Geological History of 



ance is recosrnizable by the nature of the deposits. These are 

 sandy gravels, enclosing organic remains of continental origin, 

 — plants and animals, which attracted a large voracious horde, 

 for sharks teeth and whale bones are found in the sands of 

 Bell u no associated with teeth of Khinoceros, shells of Trionjx 

 and of Emys, pine cones, leaves and trunks of palms (Sabal, 

 Palmacites). But, in general, elsewhere in the extra-alpine 

 deposits the upper Langhian corresponds, as regards depth, to 

 the bathmetric zone with brachiopods and corals. From this 

 time, the evolution of the facies undergoes a sequence the 

 exact opposite of that of the lower Miocene, the beds of the 

 middle and upper Miocene indicating a slow and continual till- 

 ing of the basin. The Helvetian is represented by marly beds, 

 deposited in a tranquil sea, in the zone of Laminaria or sea- 

 grass, inhabited by bivalves. 



The lower Tortonian corresponds to the highest part of the 

 same zone, and the deepest part of the littoral zone in the 

 broad sense ; in Friuli one can recognize in this sub-stage two 

 facies only very slightly different — a facies more strictly litto- 

 ral, richer in pelecypods, and a somewhat deeper facies, whose 

 fauna is almost excl usively of gastropods. The first corresponds 

 to a more northern zone, nearer shore; the second is located 

 farther to the south and farther offshore. And this shore was 

 a coast with an extremely gentle slope with very fine sediments 

 such as that of the present western Adriatic. 



In the upper Tortonian the sediments suddenly become very 

 coarse, the sandy or sandy-calcareous beds become of greater 

 and greater thickness and frequency until, — after a horizon 

 with a littoral facies in the strict sense (intertidal zone) charac- 

 terized by marine, brackish water, or continental faunas inter- 

 mingled, with Auriculides, gigantic oysters, etc., — the advance 

 of the deltas continued, and at the end of the Tortonian the 

 whole region had passed into continental conditions. The 

 delta, first sub-marine, had become sub-aerial in the Pontian, 

 the calcareous conglomerates of which it is formed alternating 

 with marls and variegated clays with fossil leaves, with '* molas- 

 ses" with terrestrial fossils and fresh water beds with layers of 

 lignite. 



At the close of the Miocene a continental phase returns 

 analogous to that at the beginning of the period ; but the lower 

 Miocene possesses all the characteristics of a deposit of a rocky 

 coast, while the Tortonian and Pontian, on the contrary, cor- 

 respond to delta deposits respectively sub-marine and sub-aerial. 



Thus the entire Miocene Prcadriatic gulf was filled with 

 sediments, brought to the sea at first by rivers more or less 

 mature, carrying sand and clay, then (after the Helvetian) by 

 young torrential streams bringing pebbles. torn from regions 



