Yenetia during the Neogene. 309 



ing a fauna wliicli was the direct forerunner of the recent 

 faunas of the Adriatic and the Mediterranean province in 

 general, although considerably mixed with Senegalian elements. 

 The argillaceous nature of these deposits, and the phenomena 

 of elevation and resulting intense erosion, which immediately 

 followed, easily explains the small extent to-day of the lower 

 Pliocene, now preserved in two extremely limited fragments ; 

 at Cornuda (Province of Treviso), and at S. Bartolommeo de 

 Salo (Brescia.). At Cornuda they rest conformably on the Pon- 

 tian conglomerates, dipping at about 10 degrees ; at S. Bar- 

 tolommeo they lie in deep gullies in the Senonian " Scaglia," 

 and are often found raised '^ en bloc" and almost horizontal 

 to 530 meters above the sea. 



In both cases they are fine marls of a quiet and fairly deep 

 sea, rich in Brissopsis, Schizaster, Amussium, Area, Natica, 

 etc., but deposited probably at no great distance from the coast, 

 as is indicated by the impressions of leaves of Platanus, Ilex, 

 and Rhododendron, which they contain. 



The conformity of the Pontian and Plaisancian at Cornuda 

 shows that there were no violent movements in this region, nor 

 any considerable interruption in sedimentation between the 

 Miocene and the Pliocene. The return of the sea was accom- 

 plished quietly; the waters simply submerged the deltas of the 

 basin which they had recently built up. This was merely a 

 return of the Preadriatic gulf. 



Pliocene uplift^ and the rejuvenation of the drainage system. 



It was only a short return, however, for this talassocratic"^ 

 phase did not last long. 



At Cornuda as well as at Salo proofs of a phase of intense 

 displacement are evident. At Salo there was elevation with- 

 out considerable folding, at Cornuda the latter occurred. 



The combined study of these two fragments permits us to 

 identify, with a precision very rare in our science, the geologi- 

 cal date of these movements. At Cornuda almost horizontal 

 Yillafranchian conglomerates (upper Pliocene or lowermost 

 Quaternary) lie in ravines, at times in strongly inclined Plaisan- 

 cian marls, at times on Pontian conglomerates likewise inclined, 

 at times on older formations. The Astian appears to be absent. 

 At Salo the sub-horizontal Plaisancian, lying in valleys in the 

 Cretaceous deposits, has been elevated more than 500 meters, 

 while a short distance from here at Castenedolo, the sub-hori- 

 zontal Astian lies only 120 meters above sea-level. One can 

 thus say that the period of displacement, which is manifested 

 in a simple elevation at Salo, and by folds at Cornuda, took 

 place between the Plaisancian and the Astian. 



* Talassocratic = hydrocratic — depression, or a positive movement of the 

 strand. 



