158 OLDER PLIOCENE PERIOD. [Ch. XII. 



larly stratified. He seems to have been misled by Brocchi's 

 description, who contrasts the more crystalline and solid texture 

 of the older secondary rocks of the Apennines with the loose 

 and incoherent nature of the Subapennine beds, which resemble, 

 he says, the mud and sand now deposited by the sea. 



We have endeavoured, in the last chapter, to restrict within 

 definite limits the meaning of the term alluvium ; but if the 

 Subapennine beds are to be designated marine alluvia/ the 

 same name might, with equal propriety, be applied not only to 

 the argillaceous and sandy groups of the London and Hamp- 

 shire basins, but to a very great portion of our secondary series 

 where the marls, clays, and sands are as imperfectly consoli- 

 dated as the tertiary strata of Italy in general. 



They who have been inclined to associate the idea of the more 

 stony texture of stratified deposits with a comparatively higher 

 antiquity, should consider how dissimilar, in this respect, are 

 the tertiary groups of London and Paris, although ad- 

 mitted to be of contemporaneous date, or they should visit 

 Sicily and behold a soft brown marl, identical in mineral cha- 

 racter with that of the Subapennine beds, underlying a mass of 

 solid and regularly- stratified limestone, rivalling the chalk of 

 England in thickness. This Sicilian marl is older than the 

 superincumbent limestone, but newer than the' k Subapennine marl 

 of the north of Italy ; for in the latter the extinct shells rather 

 predominate over the recent, in the former the recent pre- 

 dominate almost to the exclusion of the extinct. 



We shall now consider more particularly the characters of 

 those Subapennine beds which we refer to the older Pliocene 

 period. 



Subapennine marls. The most important member of the 

 Subapennine formation is a marl which varies in colour from 

 greyish brown to blue. It is very aluminous, and usually 

 contains much calcareous matter and scales of mica. It 

 often exhibits no lines of division throughout a considerable 

 thickness, but in other places it is thinly laminated. Near 

 Parma, for example, I have counted thirty distinct laminae in 



