Ch. XXX.] 



POST-PLIOCENE VOLCANIC ROCKS. 



Fig. 712. 



659 



Fig. 713. 



View of the Isle of Cyclops in the Bay of Trezza.* 



laid open to view, are situated in the Bay of Trezza, and may be re 

 garde d as the extremity of a promontory severed from the main land. 

 Here numerous proofs are seen of submarine eruptions, by which the 

 argillaceous and sandy strata 

 were invaded and cut through, 

 and tufaceous breccias formed. 

 Enclosed in these breccias are 

 many angular and hardened 

 fragments of laminated clay in 

 different states of alteration by 

 heat, and intermixed with vol- 

 canic sands. 



The loftiest of the Cyclopian 

 islets, or rather rocks, is about 

 200 feet in height, the summit 

 being formed of a mass of 

 stratified clay, the laminse of 

 which are occasionally subdi- 

 vided by thin arenaceous lay- 

 ers. These strata dip to the 

 N.W.j and rest on a mass of 

 columnar lava (see fig. 712) in 

 which the tops of the pillars 

 are weathered, and so rounded 

 as to be often hemispherical. 

 In some places in the adjoining 

 and largest islet of the group, 

 which lies to the northeastward 



,' lT . . , . , 1 , Contortions of strata in the largest of the 



ot that represented in the draw- Cyclopian islands 



* This view of the Isle of Cyclops is from an original drawing by my friend the 

 late Captain Basil Hall, R.N. 



