90 On the Constitution of the Territory oj Rome, with 



collect them in his classical work, under one formation ; and to 

 give to the space covered by them the expressive name of the 

 Sub-Appenine Hills. We see, from the description which he has 

 given, that these hills, on the Mediterranean side, coirtmence in 

 the ten-itory of Lucca, and after some interruption in the king- 

 dom of Naples, terminate at the southern point of Italy, near 

 Reggio, in Calabria. The marine hills of the right bank of 

 the Tiber, at Rome, the sandstone and marl of the Vatican 

 and Janiculus, forming the oldest deposites of the Roman soil, 

 entirely belong to the members o't this new formation. The 

 comparisons collected by Brocchi shew, that, in their internal 

 constitution and organic remains, they completely agree with 

 other points of the same iiature in Italy. The height to which 

 they reach on the Monte Mario is not unusual ; for on the 

 hill where the little republic of St Marino is situated, strata 

 exactly similar occur, according to the measurement of Saussure, 

 to a height of more than 2000 feet above the level of the sea. 

 The determination of the period of formation of these strata can 

 be made with greater exactness. They must have been first 

 deposited after the first elevation of the secondary chain of the 

 Appenines had already taken place ; for in the interior of the 

 latter, no trace of them is found higher than the elevation just 

 mentioned. They every where cover, wherever they exist, as well 

 the Appenine limestone as the older formations, in an unconform- 

 able and overlying position. Brocchi has, therefoit?, ranged them 

 under the Tertiary formations ; and this position has been since 

 confirmed by the examination of the organic remains. Prevost 

 endeavoured to show that they may be comjiared to the upper 

 member of the Paris Cakaire grossicre,* — a view which has been 

 since established by Rrongniart, after he had exammed this 

 district, in conjunction with Brocchi. 



The fragments of older rocks which form the sandstone and 

 rolled masses of the Janiculus, and its prolongations, are, as 

 Leopold von Buch his already observed, all derived from the 

 nearest Appenines, brought hither by tho^e enormous marine in- 

 undations which once washed the foot of the mountain chain 

 to a considerable height. These remarkable masses were formed, 



• Dcsciiption Cyfdlo'^inuc des Environs de Paris, p. TJ2. 



