178 Mr. De la Beche on the Geology oj the 



On reviewing the superior or tertiary rocks^ we seem entitled to assume, 



1. A state of repose ; the blocks of the lower breccia being angular -svith the inferior valves of 



Spondyli adhering to them, and often perforated by Lithodomi. 



2. An epoch still of repose, in which Moliusca abounded, and were enveloped in clay or marl, 



3. An epoch of violent disturbance, proved by the nature, size, and roundness of the fragments 



in the sandstone and conglomerates. 



It is exceedingly difficult to identify any of these tertiary beds with those of 

 the London and Paris basins. The more minute our divisions, the narrower 

 must be the area to which they apply. 



The conglomerates, the lower beds of which alternate sometimes with clay, 

 may possibly be referred to some epoch when the Alps were broken up. 

 They are found on all sides of the chain, and of so great thickness, that the 

 catastrophe which produced them, must have been felt at considerable di- 

 stances. In the vicinity of Nice they seem to have sufl'ered little or no dis- 

 turbance since their deposit. All the tertiary rocks indeed of this neighbour- 

 hood rest quietly on the disturbed strata of the secondary : — this is not, how- 

 ever, the case on the Swiss side of the Alps, for there the tertiary rocks are 

 disturbed with the secondary. 



II. SuPERMEDIAL OR SECONDARY RoCKS. 



1. Green-Sand Formation. 



The series next to be described presents an intimate admixture of siliceous, 

 argillaceous, and calcareous matter, in proportions which frequently vary: the 

 whole may be referred, in my opiniorl, (and I am happy to add in the opinion 

 also of M. Elie de Beaumont and Professor Buckland), to the green-sand 

 series of England and of Prance. The individual members of it, or at least 

 the principal, are as follow, commencing with that which usually occupies the 

 highest place. 



Brown micaceous Sandstone, with Marl. 



This rock occurs at Menton, and between Cap de la Mortola and Vinti- 

 miglia, being at the latter place covered by tertiary conglomerates and grey 

 marl. The section afforded by ascending the Latte for a short distance, and 

 mounting towards the Castel d'Appio*, is very instructive. The following is 

 the descending order beneath the great mass of grey clay-marl there ob- 

 servable. 



1. Compact, brown, siliceous sandstone, with Nummulites ; (strata rather thick.) 



2. Grey sandstone and marl. 



3. Coarse, quartzose sandstone, or fine-grained conglomerate. 



* Plate XXIII. fiff. 4. 



