﻿KAISER ON THE GEOLOGY OF THE VICINITY OF TRIESTE. 41 



neighbourhood of Capo d'lstria where the limestone band is broken 

 across and seems raised, while the macigno which contains it only 

 undergoes a slight twisting of its bed. 



The facts described seem to warrant the following inferences : — 



1 . The hippurite limestone lies under the nummulitic limestone, 

 and the latter under the macigno. 



2. A tranquil deposition took place from the formation of the 

 nummulitic limestone to that of the macigno. 



3. The macigno was deposited before the limestone was upheaved, 

 which is distinctly proved by the lower macigno beds having under- 

 gone the same contortions as the contiguous limestone beds, as seen 

 at Opchina. 



4. At the time of the elevation of the Karst mountains the lime- 

 stones were consolidated, while the macigno beds were yet soft and 

 flexible, and accordingly were in some cases easily bent, contorted, 

 and even thrown over, of which the best examples are on the Opchina 

 road. 



5. The macigno since it was upheaved (which must have been 

 subsequent to the nummulitic epoch) has undergone no change of 

 any consequence. 



Nevertheless many objections have been raised against several of 

 these conclusions ; for instance, the assertion that the macigno is 

 newer than the nummulitic limestone, even in the vicinity of Trieste : 

 and without entering into the intricacies of the Vienna and Carpa- 

 thian sandstones, it is clear that great caution is required in fixing 

 the age of the macigno. H. von Morlot *, who examined Istria so 

 carefully, from observations made at Pinguente, considers the macigno 

 older than the nummulitic limestone. In the same way observations 

 made at the valley of Bolliunz and the hill of S. Servola above 

 the village Dollina, would lead to the conclusion that the macigno 

 underlay the nummulitic limestone. In fact, at St. Servola, high up 

 the hill, the macigno seems to dip under the limestone ; yet on 

 the declivity towards Ospo the limestone seems to lie lower : more- 

 over the grotto of St. Servola, which sinks to a considerable depth, 

 never reaches the macigno, which would have been the case if it 

 underlay the limestone. H. von Morlot has justly observed, that a 

 bed of blue marl lies between the nummulitic beds ; but on the 

 northern side of that same mass of limestone, which presents a deep 

 perpendicular escarpment, a blue marl and then a mass of macigno 

 are seen to repose most incontestably upon the limestone. 



Let it suffice for the present to have indicated the doubts suggested 

 by these intricate relations, and to indulge in a hope that they will 

 be ere long removed. 



The very remarkable rocks constituting the promontory of Gri- 

 gnano ought here to be noticed, which advances into the sea about 

 a mile from Trieste in a N.W. direction. Blocks of rock of the size 



* It shall be my endeavour to ascertain whether at Pinguente and other places 

 in Istria that learned author has not lighted upon a band of Numrnulites, similar 

 to, if not identical with, that which I have described, and which unfortunately 

 .lie has not seen, between Pirano and Capo d'lstria. 



