88 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



but the type they present will, I think, be found to have a con- 

 siderable geological range. 



In the Venetian harbour of Govino a singular variety of this 

 limestone may be seen, and is thence traceable in rough knolls 

 running in a westerly direction to the north of the village of Po- 

 tamo. Its dark, rugged and often ochreous aspect, its sonorous 

 fracture, and its impurities, are strong features of distinction be- 

 tween it and the ordinary white limestone. It is traversed by 

 numerous crystalline veins of a yellow saccharoid carbonate of lime 

 which I have little doubt is highly dolomitic ; and it is full in- 

 ternally of small bubble-shaped cavities, some of which are empty, 

 and others contain a fine powder, the nature of which I have not 

 yet determined. I believe this limestone to be of volcanic origin, 

 or at least much changed, although no ordinary volcanic or other 

 igneous rocks have as yet been discovered in the island. 



Returning now to the white limestone of Vido and the vicinity 

 of Corfu, it will be necessary first to consider whether the geo- 

 logical age of any part of it can be determined, and this is im- 

 portant since, according to Dr. Davy, it belongs to the carboniferous 

 limestone and a conglomerate associated with it represents the 

 Old red sandstone, while, according to other accounts, the white 

 limestone is oolitic, and the conglomerate tertiary. 



The adjacent mainland with which these Corfu and Vido beds 

 must be associated contains secondary strata, considered to be 

 oolitic, and much resembling in mineral character the hardened 

 chalk of England and Ireland ; and Mr. Strickland, in describing 

 the Geology of Smyrna, mentions that the more compact beds of 

 yellowish limestone of that neighbourhood resemble the secondary 

 limestones of the Ionian Islands. The former, however, are known 

 by their fossils to be of lacustrine and tertiary origin. Mr. Strick- 

 land also, in alluding to the Geology of Zante, considers the lower 

 beds as Apennine limestone, and the upper ones as tertiary ; and 

 the presence of Hippurites renders it probable that the former at 

 least is of the Cretaceous period. 



Restricting myself to the description of the limestone of Vido 

 and the opposite shore of Corfu, I may first observe that the greater 

 portion, such as for example that of the citadel rock, the height of 

 Fort Neuf and of Fort Abraham, is very indistinctly bedded, and 

 vertical cleavage is visible on a large scale, more particularly at 

 the citadel. I have as yet in vain sought for fossils at either of 

 these localities, though the rock of Fort Abraham strongly re- 

 sembles that of Vido, which contains a considerable quantity of 

 them. Immediately below the citadel rock, forming its base, and 

 dipping under it, is the limestone of Cape Sidero which is com- 

 posed of numerous and often minutely laminated beds, from half 

 an inch to several inches in thickness. These beds are associated 

 with layers and nodules of flint, and very often present a highly 

 curious and interesting character, being made up of angular frag- 

 ments of the limestone, with occasional flints slightly displaced and 

 re-cemented together : and this brecciated structure is sometimes so 



