16 On certain Nexver Deposits in Sicily, 



represents the tertiary beds, with numerous shells of existing 

 species, No. 2. the marls, and No. 3. the bed of gypsum. 



I have already stated that the recent tertiary rocks on the 

 upper parts of the hills, consist of different kinds of limestone 

 and conglomerate. Some of the limestones have a yellow co- 

 lour, a coarse texture containing some fragments of shells, and 

 exactly resembling some of the tertiary limestones of Palermo. 

 There are two other varieties, one of which has a straw, the 

 other a bluie colour, and both of them are finer grained, and 

 much more compact than that already described. They differ 

 also materially from the other beds with which they are asso- 

 ciated, in the appearance presented by their organic remains ; 

 for they appear to have exerted a solvent property upon the 

 shells, which in most instances are removed, and casts only are 

 left; oysters, pectens, and balani being the only fossils which I 

 found entire. In many places they are so hard, that it is near- 

 ly impossible to separate the shells which they contain ; in 

 others, they are so soft, that the fossils may be removed by the 

 hand. 



The beds of gypsum on the south side of the hill are a good 

 deal contorted and fractured. They have a grey colour, a large 

 scaly fracture ; but in a few places are white and granular, and 

 contain seams of transparent, white, foliated selenite. 



The oysters, pectens, and balani are so perfectly preserved, 

 that in many instances they retain their original colours. Be- 

 sides these, I found casts of a large Panopcea P. ? of a large 

 cardium, venus, valuta, natica, an echinus, he. 



The hills on which Leonforte, Asaro, and St Filippo d'Ar- 

 gire are situated, are all of them composed of recent tertiary 

 rocks, similar to those of Castro Giovanni, and all present high 

 perpendicular cliffs towards the south, the strata dipping in the 

 opposite direction ; and it is farther of importance to observe, 

 that a line drawn from Castro Giovanni through the highest 

 points of these hills, which are invariably at the very edge of 

 their southern escarpments, will be found parallel to the princi- 

 pal chain, and if prolonged to the east and west, will also cor- 

 respond to other lines of escarpments in the elevated tertiary 

 rocks. 



In almost all the valleys on this side of the chain, great ac- 



