NKWF.R PLIOCENE PERIOD. 



[Ch. VI. 



from Catania to Syracuse, has an opportunity of observing, 

 on the sides of the valley, many deep sections of the modern 

 formations above described, especially if he makes a slight 

 detour by Sortino and the Valley of Pentalica. 



The whole series of strata, in the Val di Noto, is divisible 

 into three principal groups, exclusive of the associated volcanic 

 rocks. The uppermost mass consists of limestone,, which some- 

 times acquires the enormous thickness of seven or eight him 

 dred feet, below which is a series much inferior in thickness, 

 consistina; of a calcareous sandstone, cono-lomerate and schistose 



O ' O 



limestone, and beneath this again, blue marl. The whole of 

 the above groups contain shells and zoophytes, nearly all of 

 which arc referrible to species now inhabiting the contiguous 

 sea. 



Castrojriovanni. No. 5. 



Girgenti. 



a, Great limestone of Val di Noto. 



It, Schistose and arenaceous limestone of Floridia ; &c. 



c, Blue marl with shells. 



d, White laminated marl. 



e, Blue clay and gypsum, c. without shells. 



Great limestone formation (a, diagram No. 5). In mineral 

 character this rock often corresponds to the yellowish white 

 building-stone of Paris, well known by the name of Calcaire 



o 



growler, but it often passes into a much more compact stone. 

 In the deep ravine-like valleys of Sortino and Pentalica, it is 

 seen in nearly horizontal strata, as solid and as regularly bedded 

 as the greater part of our ancient secondary formations. It 

 abounds in natural caverns, which, in many places, as in the 

 valley of Pentalica, have been enlarged and multiplied by ar- 

 tificial excavations. 



