182 Mr. De la Beche on the Geology of the 



3. Green-grained beds full of Belemnites, Ammonites, Nautili, Pcctens. 



4. Grey marl. 



5. Grey, arenaceous limestones, containing large Gryphiiea colutnba^ chalcedonified strata 



nearly vertical. 



6. Grey limestones, more arenaceous, containing small siliceous Gryphites, (dip becoming 



less highly inclined.) 



7. Brown, calcareous gritstone. 



8. Brown and grey arenaceous beds, containing numerous alcyonic remains mostly siliceous, 



Echinites, Pectens, Terebratulse. 



b. Mont Revel. 



1. Dolomite. 



2. Compact, light-coloured limestone, dip small, E.N.E. 



3. Green-grained beds, containing Belemnites, Ammonites, Nautili. 



4. Grey marl of considerable thickness, containing a few beds of marly limestone. 



5. Grey, arenaceous limestone, mixed with a little marl. 



6. Arenaceous beds, containing siliceous alcyonic bodies — dip N.E. highly inclined. 



2. Light-coloured Limestone and Dolomite. 



Limestone of Mr. Allan. 



These rocks are so intimately connected as to constitute only parts of one 

 formation. They are the base of all the country near Nice, and form the 

 mass of Mont Cao and Pacanaia ; the former, according to M. Verany's 

 observations, is 2800, and the latter 1950 feet above the sea. 



a. Limestone. 



De Saussure first noticed the resemblance of this to the limestone which 

 occurs at the base of the Saleve near Geneva*. It is light-coloured, very 

 compact, and sometimes veined with calcareous spar, and sometimes, though 

 rarely, with cherty flint; the strata are two, three, or four feet in thickness, 

 and generally well defined. 



At Turbiglia it suppHes crushing-stones for the olive mills. Near the same 

 place it was quarried by the ancients to build the tower or trophy of Augustus, 

 whence the town derived its ancient, and, by corruption, its modern name. 

 The quarries there are nearly in the state now in which they were left by 

 the Romans. 



h. Dolomite {Saccharine Limestone of Fanjas St. Fond, Allan, and Risso). 

 The dolomite when most crystalline is white ; the other varieties present 



* Voyage dans les Alpes, vol. iii. 



