300 G. Stefanini — Outline of the Geological History of 



continent which was rising. In the Lower Miocene are found 

 sands and " calcaires grossiers-' with glanconite, passing into 

 " molassic " deposits, or into marly limestones which are some- 

 times employed in the manufacture of hydraulic lime. A 

 fauna rather rich in pectens and echinoids, with some corals 

 and barnacles characterises the stages of this period, fairly easily 

 recognizable, — the Aquitanian and the Langhian (Burdigalian). 



The Aquitanian rests on the upper Oligocene in Yicenza, Tre- 

 viso, and Belluno ; to the west of this central region (Yerona, 

 Trentino) the Aquitanian is transgressive on terrains of differ- 

 ent ages, more or less ancient; to the east (Friuli) it is absent, 

 and it is the Langhian that is the immediately succeeding stage 

 resting directly on the Eocene Flysch or on the Cretaceous 

 limestones. And yet in western Yenetia there are spots where 

 the Langhian is transgressive, for example, in the immediate 

 vicinity of Yerona. 



The middle Miocene presents a facies entirely marly at the 

 base (Helvetian) ; a marly sand at the top (Tortonian) ; glaucon- 

 ite appears to be absent even in the clastic condition. In the 

 Tortonian the '^ molasses " alternate with layers of pebbles, 

 more and more thick and frequent. The fauna is especially 

 rich in molluscs of a tropical or subtropical type. The middle 

 Miocene is largely developed in eastern and central Yenetia ; to 

 the west deposits of this age are known only in Yalsugana and 

 in the neighborhood of Bassano ; from all the remainder of 

 Yicenza, Yerona, and the region around the Lago di Garda it 

 has been removed by erosion. 



The upper Miocene is represented by an alternation of con- 

 glomerates, marls, and " molasses," many times repeated, rich 

 in impressions of leaves and in terrestrial and fresh water 

 shells. Occasionally teeth of Dinotherium and of mastodons 

 are found in lignite beds, which form a very characteristic 

 horizon at the base of the series. The upper Miocene forma- 

 tions cover large areas in Friuli, Treviso, and in the Trentino; 

 they have not yet been recognized farther to the West. 



Finally, the Pliocene, reduced by erosion to extremely 

 restricted remnants, has its usually marly fossils, and presents 

 a curious mixture of echinoids and stenobolic marine, almost 

 bathyal molluscs, together with leaves of continental trees. 



Because of the often displaced position of the beds, and of 

 the nature of the rocks, — all more or less easily eroded, — the 

 Neogene deposits as well as the Paleogene generally do not 

 form outcrops of great extent in the Yenetian region. On the 

 contrary they are separated into numerous remnants, spread in 

 part at the edge of the prealpine chain, facing the plain (extra- 

 alpine remnants), and in part in the interior of the mountain 

 region (intra-alpine remnants). 



