78 NEWER PLIOCENE PERIOD. 



[Ch.VII. 



observed in the entire thickness of subjacent beds of sand and 

 clay. 



The dip of the marine strata, at the base of Etna, is by no 

 means uniform ; on the eastern side, for example, they are some- 

 times inclined towards the sea, and at others towards the moun- 

 tain. Near the aqueduct at Aderno, on the southern side, I 

 observed two sections, in quarries not far distant from each 

 other, where beds of clay and yellow sand dipped, in one locality, 

 at an angle of forty-five degrees to the east-south-east, and in 

 the other at a much higher inclination in the opposite direction. 

 These facts would be of small interest, if an attempt had not 

 been made to represent these mixed marine and volcanic de- 

 posits which encircle part of the base of Etna, as the outer 

 margin of a so-called ( elevation crater*.' 



Near Catania the marine formation, consisting chiefly of 

 volcanic tuff thinly laminated, terminates in a steep inland cliff, 

 or escarpment, which is from six hundred to eight hundred feet 

 in height. A low flat, composed of recent lava and volcanic 

 sand, intervenes between the sea and the base of this escarp- 

 ment, which may be well seen at Easano. (f, diagramNo.il.) 



Eastern side of Etna Bay of Trezza. Proceeding north- 

 wards from Catania, we have opportunities of examining the 

 same sub-Etnean formations laid open more distinctly in the 

 modern sea cliffs, especially in the Bay of Trezza and in the 

 Cyclopian islands (Dei Earaglioni), which may be regarded as 

 the extremity of a promontory severed from the main land. 

 Numerous are the proofs of submarine eruptions of high an- 

 tiquity in this spot, where the argillaceous and sandy beds have 

 been invaded and intersected by lava, and where those peculiar 

 tufaceous breccias occur which result from ejections of fragmen- 

 tary matter, projected from a volcanic vent. I observed many 

 angular and hardened fragments of laminated clay (creta), in 

 different states of alteration, between La Trezza and Nizzitta, 

 and in the hills above Aci Castello, a town on the main land 

 contiguous to the Cyclopian isles, which could not be mistaken 



* See vol. i. chap. xxii. 



