S70 Mr Jameson on the Natural History a7id Statistics 



sions of Cerigo, the east coast of the northern division, except in 

 a few points where the mica-slate juts down on the coast, the 

 extreme end of the island, all the high lands of Cerigotto, some 

 of the islets, as Ovo, Drajoneres, &c. consist of this limestone. 

 We find the same limestone resting on the clay-slate where the 

 northern district joins that of Milopotamo, and on mica-slate at 

 the junction of it and Castrisso. 



GreywacJce.^^Tiy'ing immediately upon the limestone is a rock 

 which I have called greywacke. It may be divided into upper 

 and lower ; the lower is composed of fragments of various sizes 

 held together by a clayey basis, and consisting of quartz, flinty- 

 slate, jasper, and limestone, the latter being the most abundant ; 

 in the upper the particles are smaller, and the rock assumes the 

 slaty structure. But sometimes the particles disappear altoge- 

 ther, and then it is either slaty or merely a clayey amorphous 

 mass of a blue or red colour, which is used here for covering 

 the roofs of houses. The greywacke and its slate sometimes 

 alternate, but I did not observe that to be the case in Cerigo. 

 They are met with, covering the lower parts of the limestone, 

 as at the foot of a mountain-chain or the lower lateral chains. 

 In several parts of the mountain-ranges we see them very dis- 

 tinctly, extending from their acclivities into the valleys, and 

 forming hilly ground. 



The following minerals were noticed in this formation during 

 a hasty examination. Qw«r^^.— Various subspecies and varieties 

 of this mineral occur in the limestone and greywacke. Common 

 quartz was met with abundantly in the lower parts of the lime- 

 stone, forming veins ; these veins were sometimes of a red but 

 oftener of a green colour. The subspecies flinty slate occurs in 

 veins in the greywacke, as well as (although in smaller quantity) 

 its variety called Lydian stone. In the lower part of the lime- 

 stone, veins of common jasper of a red colour are met with. 

 Manganese Ore. — The black and grey species of this ore occur 

 along with the jasper just mentioned. Both the red and black 

 compact iron-ores were also observed occurring in veins. 



Although in this sketch we have only mentioned a few mine- 

 rals which occur imbedded, yet it is important to know that the 

 rocks of the transition class are the repositories of the principal 

 ore-mines and roofing-slate quarries now worked, also of several 



