SCIENTIFIC NEWS. 309 



pable of mutual penetration. The outer lamella? are the 

 least hard and dense, and therefore yield the easiest to the va- 

 rious causes which occasion the disintegration of rocks. 



March 19^^, 1813. 



Mr. Webster exhibited specimens of the rocks containing v 

 freshwater shells recently discovered by him in the Isle of 

 Wight. 



A paper on the rocks of Clovelly, in Devonshire, with illus- 

 trative drawings, by the Rev. I. J. Conybeare, was read, and 

 thanks were voted for the same. 



The fishing town of Clovelly is situated in a narrow ravine 

 on the north coast of Devon, about 22 miles west of Ilfra- 

 combe. The shore is precipitous, being formed of cliffs about 

 130 or 140 feet in height, intersected by narrow alternations 

 of Granwarke and Granwarke slate, curved and contorted in 

 the most capricious way imaginable. No organic remains were 

 observed in them, nor any foreign minerals, except opake white 

 quartz, forming numerous veins. Nearly the whole of North 

 Devonshire is composed of the rock just described, which is 

 locally distinguished into Duns tone and Shllat, the latter being 

 the slaty Granwarke, and the former the compact : it is al- 

 ways very irregular in its stratification, is destitute of metallic 

 veins, alternates with transition limestone, and, where it does 

 so, occasionally contains organic remains. It also, in one in- 

 stance at least, alternates with thick beds of a kind of culm : 

 its veins besides quartz occasionally offer calcareous spar. KiU 

 las, which Mr. C. is inclined to regard as a variety, not of 

 nuca-slate, but of. clay slate, is contorted in its stratification 

 only in the neighbourhood of the Granwarke, is traversed 

 almost through its whole extent by frequent veins or dykes of 

 a porphyritic rock which does not pass into the Granwarke, 

 contains sometimes topaz, and not unfrequently garnet : its 

 veins are often filled with chlorite, mica, and crystallized 61- 

 spar, and also contain tinstone, grey cobalt ore, &c. These 

 characters, in the opinion of the author of this paper, form a 

 sufficient mark of distinction between the Granwarke and the 

 Killas of the West of England. 



A paper on the Isle of Staffa, by Dr. Mac Cullocb, was 

 read, and thanks were voted for the same. 



Th» 



