Cn. VI.] 



IN THE ISLAND OP SICILY. 



75 



to expose to view these marks of boring-shells in the interior of the cave, 

 it was necessary first to remove a mass of breccia, which consisted of 



Fi«. 93. 



////// «*L 

 ///// V////!^ 



a. Monte Grifone. 5. Cave of San Ciro.* 



c. Plain of Palermo, in which are Newer Pliocene strata of 

 limestone and sand. d. Bay of Palermo. 



numerous fragments of rock, and an immense quantity of bones of the 

 mammoth, hippopotamus, and other quadrupeds, imbedded in a dark 

 brown calcareous marl. Many of the bones were rolled, as if partially 

 subjected to the action of the waves. Below this breccia, which is about 

 20 feet thick, was found a bed of sand filled with sea-shells of recent 

 species ; and underneath the sand, again, is the secondary limestone of 

 Monte Grifone. The state of the surface of the limestone in the cave 

 above the level of the marine sand is very different from that below it. 

 Above, the rock is jagged and uneven, as is usual in the roofs and sides 

 of limestone caverns ; below, the surface is smooth and polished, as if 

 by the attrition of the waves. 



The platform indicated at c, fig. 93, is formed by a tertiary deposit 

 containing marine shells almost all of living species, and it affords an 

 illustration of the terrace of deposition, or the last of the two kinds be- 

 fore mentioned (p. 74). 



There are also numerous instances in Sicily of terraces of denudation. 

 One of these occurs on the east coast to the north of Syracuse, and the 

 same is resumed to the south beyond the town of Noto, where it may 

 be traced forming a continuous and lofty precipice, a b, fig. 94, facing 

 towards the sea, and constituting the abrupt termination of a calcareous 

 formation, which extends in horizontal strata far inland. Tbis precipice 

 varies in height from 500 to 700 feet, and between its base and the sea 

 is an inferior platform, c b, consisting of similar white limestone. All 

 the beds dip towards the sea, but are usually inclined at a very slight 

 angle : they are seen to extend uninterruptedly from the base of the 

 escarpment into the platform, showing distinctly that the lofty cliff was 

 not produced by a fault or vertical shift of the beds, but by the removal 

 of a considerable mass of rock. Hence we may conclude that the sea, 

 which is now undermining the cliffs of the Sicilian coast, reached at 

 some former period the base of the precipice a b, at which time the sur- 



* Section given by Dr. Christie, Edin. New Phil. Journ. No. xxni. called by 

 mistake the Cave of Mardolce, by the late M. Hoffmann. See account by Mr. S. 

 P. Pratt, F. G. S. Proceedings of Geol. Soc. No. 32, 1833. 



