and the Phenomena acco7npany'mg their Elevation. 23 



None of these beds have any resemblance to melaphyre, nor do 

 they appear on the other hand to belong to true volcanic rocks. 

 Fragments and grains of them are found in some of the super- 

 incumbent limestones *. 



The base of the small island of Conenti is composed of beds 

 of hard nummulite limestone having a yellow, brown, or white 

 colour. It contains nummulites in some situations, but not in 

 great abundance, and I thought I could distinguish some traces 

 of hippurites. They extend the whole way round the island, 

 rising only a ^ew feet above the level of the sea. Resting upon 

 them are beds of a loose yellow limestone, or marl of a grey 

 colour, and of the white cretaceous limestone already so frequent- 

 ly mentioned. They are all perfectly horizontal, and are capped 

 by a thin bed of a harder limestone, which has protected them 

 against the attacks of the weather, and has prevented them 

 from having been long ago completely washed away. The 

 greatest height of the island is probably not more than 30 or 40 

 feet. I found a few microscopic shells in the white and grey 

 marls, similar to those found in the same formation in other parts 

 of Sicily. 



Conclusions. 

 Notwithstanding the very limited and imperfect nature of 

 the preceding observations, I believe that they will nevertheless 

 enable us to arrive at some very important theoretical conclu- 

 sions, which I shall now proceed to consider ; and first in regard 

 to the bone-breccias. From the situation of these breccias, both 

 at Palermo and Syracuse, there can be no doubt that the ex- 

 tinct quadrupeds existed at a period long posterior to that in 

 which the Mediterranean began to be inhabited by its present 

 species of mollusca, radiata, and zoophytes, and before the last 

 great convulsion, which raised a great part of Sicily above the 

 level of the sea. The smooth water-worn surface of the cave of 

 Santo Giro, and of some of those at Syracuse, and the nume- 

 rous holes left by perforating marine mollusca, force upon us 

 the conclusion, that these caves were long under the surface of 

 the sea, and this at a period long posterior to the formation of 



• Dr Davy has been so kind as to examine some specimens of the white 

 hippiirite limestones, in order to determine whether they contain magnesia. 

 No trace of this earth could be detected. 



