MESOZOIC AND KAINOZOIC GEOLOGY IN EUROPE. 325 



contemporaneous faulting took place along the line of erup- 

 tion, and the floor of the sea outside this line was let down. 

 Hence between the volcanic ridge and the land there was 

 shallow water, and outside the ridge a deep sea. Within 

 the former marls and shales were rapidly deposited ; while 

 in the latter the dolomites and limestones were laid down, 

 and they owe their great and suddenly increasing- thickness 

 to the subsidence of the sea-floor. Corals grew within the 

 shallow water and upon the volcanic ridge, forming the 

 lenticular masses which are known as " cipit limestones," 

 but the dolomites themselves appear to have been formed 

 by algae and mollusca. 



At a later period the subsidence became general and 

 the dolomites spread over the barrier into the former 

 shallow water area ; while towards the close of the Triassic 

 period, the sea again became shallower, and shallow water 

 deposits spread outwards from the north towards the south. 



Much of the difficulty which has been felt in the ex- 

 amination of the Tyrolese Trias has been due to the fact 

 that deposition was going on simultaneously under very 

 different conditions in different areas. And it is worthy of 

 note that the same difficulty has been experienced in South- 

 ern Italy. Near Lagonegro, in the province of Basilicata, 

 there are developed nodular limestones, silicious schists with 

 radiolaria, and dolomitic limestones. The mutual relations 

 of these beds are not clear ; but Lorenzo (20) has come to 

 the conclusion that they are simply heteropic developments 

 of the same period. From an examination of the fossils, he 

 places them about the horizon of the Cassian and Raibl 

 beds of Tyrol. 



In the Balearic Isles, according to Nolan (24), the 

 Upper Trias is divisible into three distinct horizons, 1 which 

 correspond very closely with those of Southern Tyrol ; and 

 these islands must therefore be placed in Mojssovics' Medi- 

 terranean Province. 



1 These are, in ascending order :— 



1. Zone of Trachyceras Curionii and T. Vilanovce. 



2 . Zone of Daonella Lom/neli. 



3. Zone of Hoernesia pseudosocialis and Monotis salinaria. 



