302 G. Stefanini — Outline of the Geological History of 



the east, as well as one on the north and the west, while it 

 opened broadly to the south. The characteristics of the facies 

 of the different remnants, compared with their distance from 

 the supposed edge of this gulf, confirms this h3^pothe5is ; for 

 the beds of the same horizon, which a minute study has often 

 permitted me to recognize in the different areas, show in 

 general a facies less littoral in those remnants farthest removed 

 from the shores, and vice-versa. 



In conclusion, the Preadriatic Gulf was only an arm of the 

 sea, which during the ]^eogene occupied the valley of the Po, 

 and in which were deposited the now classic beds of the Col- 

 line de Turin, and of Langhe, Sarravalle, Tortona, Plaisance, 

 and Asti ; beds with which the formations of Yenetia are very 

 closely allied paleontologically and geologically. 



History of the Preadriatic Gulf. 

 Form and extent of the Gulf. 



What has been the history of this gulf during the Xeogene 

 period ? And, first, how did it originate ? 



Presumably during the lower Oligocene the Venetian region 

 was almost entirely submerged by the sea, which deposited the 

 beds of Montecchio Maggiore. Perhaps, connected with the 

 basic eruptions of Yicenza, a regression occurred at the end 

 of the lower Oligocene since the deposits with lignite and 

 impressions of leaves, so frequent among the beds of this 

 period in Yicenza, indicate close proximity to a continent. 

 Islands or peninsulas then occupied the neighborhood of 

 Yeronaand theTessini hills; eastern Yenetia had also emerged. 

 The upper Oligocene, or Chattian, marks an incursion of the 

 sea, and is characterized by beds with Nullipores, and Lepido- 

 cycliria, accompanied by small nummulites. 



The shores of this Chattian gulf, occupying a part of Yicenza, 

 Treviso, and of Belluno, are relatively easy to identify, for they 

 correspond to the boundary between the region where the lower 

 Miocene is conformable on the upper Oligocene, and the region 

 where the Miocene is transgressive. 



The Preadriatic Miocene gulf was due to a transgressive 

 movement of the sea and it reproduced in the closest manner, 

 the form of the preceding Oligocene gulf. This Miocene 

 transgression, if my deductions are correct, does not appear to 

 have been produced suddenly. The w^estern borders of the 

 gulf were already more or less completely invaded by the sea 

 at the beginning of the Aquitanian while the eastern border 

 remained dry until the Langhian. Indeed, in the beds in the 

 Province of Yerona (as distinguished from those of Yerona 

 proper, where it is the Langhian which rests in ravines in the 



