and the Phenomena accompanying their Elevation. 13 



which has cut its way through it, and has thus produced preci- 

 pitous banks of 50 or 60 feet in height. It consists of hght 

 coloured clay, containing numerous large blocks of sandstone 

 with occasionally some of limestone. ■> 



The whole of the great central chain, which forms one of the 

 most prominent and important features in the geology of Sicily^ 

 is composed in this part entirely of the sandstone formation, 

 which here rises to very great heights. The mountain of St 

 Diana, which is the highest in the neighbourhood of Mistretta, 



1 found to have an elevation of 3875 feet above the level of the 

 sea * ; but it is situated a httle to the north of the principal 

 crest of the chain, and is overtopped by many others within 

 sight, the loftiest of which is the Madonia, whose summit, even 

 on the 8th of June, was still white with numerous large patches 

 of snow f. 



The direction of the strata at Mistretta appears ta be nearly 

 parallel to the general direction of the chain itself, viz. about 

 W. 18 S., and they are seen distinctly to dip away from an an- 

 ticlinal line, which passes across the mountain of S. Diana, 

 extends between the hill on which the castle stands and the 

 small hill of St Catarina on its north, and thence across the 

 valley to the east of Mistretta. The highest part of the chain 

 here is the Monte di Castelli, which is considerably higher than 

 the St Diana, has an even summit and a direction nearly the 

 same as that of the chain ; but it is worthy of remark, that two 

 distinct bearings may be observed in the strata, one being nearly 

 W. 15 S. \, the other apparently north and south ; the former 

 having a southerly, the other an easterly dip. In the valley 

 which runs down from the east part of the Monte Castelli to- 

 wards Nicosia, the strata have a direction of S. 15. W. and dip 

 towards the east. Two distinct directions are also observable 

 in the sandstone at Nicosia, where certain vertical strata bear 

 W. 18 S., and others less inclined, and not quite so distinct, 



* From a barometrical observation at the Castello di Tusa, at half-past 



2 p. M., on the 7th of June, and one on the summit of the mountain, at the 

 same hour of the following day. *^' 



+ Ferrara makes this mountain only 3660 feet above the level of the sew 

 which it is needless to say must be too low by some thousand feet. 

 X About east and west by the compass. 3 



